GB2192049A - A wrap-around back boiler - Google Patents

Abstract

A wrap-around back boiler 200 comprises a main rear tank and a pair of outwardly directed main side tanks 3,4 connected to the rear tank and defining therewith a channel-shaped firebed and flue enclosure. A plurality of additional tanks 202,203,204,205 extend into the enclosure to define a tortuous passageway for combustion gases which is closed at the front by a removable front bridging plate (not shown). The passageway includes interconnected legs which are arranged to direct the gases successively across the enclosure from one main side tank 3 towards the other main side tank 4. At least two of the additional tanks are connected to and extend inwardly of the side tanks and the additional tanks may be inclined rather than horizontal. <IMAGE>

Description

GB2192049A 1 SPECIFICATION bridging member extending between at least two

of the additional tanks; the main tanks, A wrap-around back boiler additional tanks and front bridging member to gether defining a tortuous flue gas passage The present invention relates to wrap-around 70 way which extends from an inlet adjacent a back boilers for domestic fireplaces, such firebed to a discharge outlet to an exhaust boilers being used for a hot water supply sys- flue, the front bridging member being remova tem, a central heating system or for a combi- ble to leave a front opening allowing access nation of both. to the passageway for cleaning, the additional These domestic boilers are generally re- 75 tanks being so arranged that in use, the flue ferred to as wrap-around back boilers because gases travelling along the passageway are they usually are arranged in domestic fire- constrained to move laterally between the places and can be said to surround three main side tanks.

sides of the fire, hence the term "wrap- In one embodiment of the invention the around back boiler" or simply "back boiler". 80 front bridging member comprises a removable Fuel conservation and the relatively high front plate for the combustion gas passage- cost of fuel has led to a considerable increase way.

in concentration by designers on the construc- Preferably the passageway includes at least tion of such back boilers. The major area of three interconnected successively rising and improvement has been directed towards pro- 85 failing legs. Usually the boiler includes two viding an increased heat exchange surface and combustion gas passageways, each having at thus a more efficient heat transfer from the least three interconnected successively rising boiler to the use required. Unfortunately, while and failing legs.

some extremely useful and efficient designs of In one embodiment of the invention the back boilers have been designed one of the 90 passageways extend from a common inlet. In major problems is that if they are not effici- this case preferably the inlet is substantially ently cleaned the thermal efficiency of the centrally disposed between the main side boiler reduces dramatically in use. Thus, it is tanks. Typically the passageways include a essential that such boilers be cleaned regularly common central rising leg and successively and efficiently so that all the heat transfer sur- 95 rising and falling legs on each side of the cen faces are clean and are not allowed build up a tral rising leg. Usually each passageway in deposit of soot. After soot has built up on cludes two successively rising and falling legs the surface of a boiler it is extremely difficulty on each side of the common central rising leg.

to remove except by chemical means. One of In a particularly preferred embodiment of the the major reasons why boilers are often diffiinvention the boiler comprises a pair of inlet cult to clean is due to restricted access. auxiliary side tanks connected to the rear tank It has been proposed to provide wrap- and respective side tanks and spaced-apart to around back boilers in which a plurality of hol- define therebetween the substantially central low fins project forwardly of the hollow back inlet rising leg, and an upper auxiliary central portion and communicate therewith. A remo- 105 tank connected to the rear tank and extending vable plate conforming to the shape of the downwardly between the inlet side auxiliary fins covers the front of the fins. The fins and tanks and each main side tank to form, on plate together define a plurality of flues above each side of the inlet rising leg, a successive the combustion zone. Such removable plates intermediate falling leg and an outlet rising leg are generally in close contact with all the fins 110 for combustion gases. Usually each inlet aux or slightly spaced therefrom. Again, there iliary side tank initially extends inwardly from a have been problems with such boilers in that main side tank and is then directed upwardly.

while the basic idea of providing a removable Typically each inlet auxiliary side tank is ini plate is attractive as the flues are accessible tially inclined upwardly from a main side tank.

for cleaning such boilers are not particularly 115 Usually each inlet auxiliary side tank initially efficient. extends inwardly substantially at right angles The present invention is directed towards to the main side tank to which it is con- providing an improved construction of wrapnected. Preferably each inlet auxiliary side tank around back boiler which will have not only is then directed upwardly substantially parallel access for cleaning the heat transfer surfaces 120 to a main side tank.

of the boiler but which will also be thermally Preferably the upper auxiliary central tank in eff icient. cludes a top roof portion extending over the According to the invention there is provided first rising leg of the combustion gas passage a wrap around boiler comprising a main rear way. The top roof may either include a sub tank; a pair of outwardly directed main side 125 stantially flat portion extending forwardly sub tanks connected to the rear tank and defining stantially at right angles to the main rear tank therewith a channel-shaped firebed and flue or a substantially inverted V- shaped portion enclosure; a plurality of additional tanks con- having a substantially centrally disposed apex.

nected to at least one of the main tanks and Typically the upper auxiliary central tank in extending into the enclosure; and a front 130 cludes a pair of depending side portions ex- 2 GB2192049A 2 tending downwardly between the inlet side side tanks and spaced-apart to define there auxiliary tanks and each main side tank to between a central opening for flue gases and form, on each side of the inlet rising leg, a an upper central auxiliary tank above the side successive intermediate failing leg and an out- auxiliary tanks connected to the rear tank and let rising leg for combustion gases in each 70 spaced-apart from the main side tanks to de passageway. fine an opening through which gases rising In a particularly preferred embodiment of the from the central opening between the side invention the boiler includes an inlet additional auxiliary tanks pass.

tank, bridging, the main side tanks adjacent In a further embodiment of the invention the the front plate. Typically the inlet additional 75 boiler includes an inlet additional tank, bridging tank includes a rearwardly and downwardly the side tanks adjacent the front plate. The extending top wall. Preferably the inlet addi- inlet tank may be rearwardly and upwardly in tional tank includes a rearwardly extending clined.

bottom wall. Preferably the boiler includes retaining In a further embodiment of the invention the 80 means for the front plate. Typically the retain boiler comprises a pair of upper auxiliary ing means comprises a retaining bracket bridg bridging members extending from a respective ing the side tanks adjacent the discharge out side tank and the rear tank and being spaced- let. Usually the retaining bracket comprises an apart to define therebetween the discharge angle bracket having a downwardly extending outlet to an exhaust gas flue. Preferably the 85 first arm and an interconnected inwardly ex boiler also includes a rear auxiliary bridging tending second arm, a top edge of the front member extending from the main rear tank to plate being retained, in use behind the first define, together with the side auxiliary bridging arm. Typically the removable front plate is members the discharge outlet to an exhaust supported, in use, on the inlet additional tank.

gas flue. Each bridging member may comprise 90 In a particularly preferred embodiment of the a bridging plate extending from a respective invention the additional tanks abut, in use main tank or an upper bridging side tank con- against the front plate.

nected to the main rear tank and a respective Preferably the boiler includes a damper for side tank. Each bridging tank may be substan- the discharge outlet from the combustion gas tially wedge-shaped in transverse cross sec- 95 passageway.

tion. The invention also provides a tool for clean In a further embodiment of the invention the ing a back boiler having a handle and a clean combustion gas flue passageway includes at ing head wherein the handle or head includes least three interconnected legs which extend means for operating a damper and/or a remo successively sidewardly, at least partially 100 vable front plate for the boiler. Preferably a across the enclosure, towards and away from cut-out slot is provided in the cleaning head the main side tanks. In this case the boiler for engaging with a complementary lug on a may include a lower additional tank connected damper and/or a removable front plate.

to the main rear tank and spaced-apart from The invention will be more clearly under at least one main side tank to define an inlet 105 stood from the following description thereof opening for combustion gases, at least one given by way of example only with reference intermediate additional tank above the lower to the accompanying drawings in which:

tank and connected to the rear tank to define, Fig. 1 is a perspective view of a wrap together with the lower additional tank a sk around back boiler according to the invention, dewardly extending leg of the combustion gas 110 Fig. 2 is a perspective, partially cut-away, passageway, and an upper additional tank view of the boiler of Fig. 1 with a front plate connected to the rear tank and above-the in- and damper plate removed, termediate tank to define therewith another si- Fig. 3 is a front, partially cross sectional dewardly extending leg of the combustion gas view of the boiler of Fig. 2, passageway. 115 Fig. 4 is a side, partially cross sectional The additional tanks may -be parallel with view of the boiler of Fig. 1, each other. Alternatively at least some of the Fig. 5 is a diagrammatic perspective view of additional tanks are inclined inwardly upwardly portion of the boiler of Figs. 1 to 4 illustrating with respect to the main side tanks. At least the use of a hand tool for removing the front some of the additional tanks may also be in- 120 plate, clined inwardly downwardly with respect to Fig. 6 is a diagrammatic perspective view the main side tanks. illustrating the use of a hand tool in cleaning In a particularly preferred embodiment of the the boiler of Figs. 1 to 4, invention the boiler comprises a lower central Figs. 7 to 9 are perspective views of three auxiliary tank connected to the rear tank and 125 different constructions of back boiler similar to spaced-apart from each main side tank to de- the boiler of Figs. 1 to 4, with a front plate fine an opening through which combustion and damper plate removed, gases pass, a pair of intermediate side aux- Figs. 10 and 11 are perspective partially ex iliary tanks above the lower central auxiliary ploded views of two different constructions of tank and connected respectively to the main 130 back boiler similar to the boiler of Figs. 1 to 3 GB2192049A 3 4, portion 18 which extends inwardly from a Figs. 12 and 13 are perspective views of main side tank 3A and an upper portion 19 two different constructions of back boiler simi- which is directed upwardly substantially paral lar to the boiler of Figs. 1 to 4, with a front lel to the main side tanks 3A It will be noted plate and damper plate removed, 70 that the lower portion 18 of the auxiliary side Figs. 14 and 15 are perspective, partially tanks 15,16 are inclined upwardly from adja exploded views of two different constructions cent respective side tanks 3,4 for ease of of back boiler similar to the boiler of Figs. 1 cleaning and for directing combustion gases to 4, rising from a firebed into the inlet rising leg Figs. 16 and 17 are perspective views of 75 17 of the flue gas passageway 11.

two further constructions of back boiler similar An upper auxiliary central tank 20 is con to the boiler of Figs. 1 to 4 with a front plate nected to and extends forwardly of the main and damper plate removed, rear tank 2 and includes a central top roof Fig. 18 is a perspective view of another portion 21 and a pair of depending side por construction of boiler with a front plate and 80 tions 22,23 which extend downwardly sub damper plate removed, and stantially parallel to the main side tanks 3,4 Figs. 19 to 21 are perspective views of into the space defined between the auxiliary three different construction of boiler, similar to side tanks 15,16 and the respective main side the boiler of Fig. 18, with a front plate and tanks 3,4. The roof portion 21 extends over danper plate removed. 85 the first rising leg 17 of the combustion gas Referring to the drawings and initially to passageway so that combustion gases rising Figs. 1 to 6 thereof there is illustrated a wrap- through the central inlet leg 17 between the around back boiler according to the invention auxiliary side tanks 15,16 are turned into in indicated generally by the reference numeral 1. termediate falling legs 24,25 defined between The wrap-around back boiler comprises a 90 the side portions 22,23 of the upper auxiliary main rear tank 2 and a pair of outwardly di- central tank 20 and the respective upper por rected main side tanks 3 and 4 respectively tions 19 of the auxiliary side tanks 15,16. The which form extensions of the rear tank 2. The gases are then turned again through 180 by rear tank 2, side tanks 3 and 4 and a remova- the lower portion 18 of the auxiliary side ble front bridging member, in this case a re- 95 tanks 15,16 into second rising legs 26,27 de movable front plate 5, define a conbustion gas fined between the side portions 22,23 of the flue enclosure and a lower portion of the rear upper auxiliary central tank 20 and the respec tank 2 and side tanks 3 and 4 form a firebed tive main side tanks 3,4. The gases then pass enclosure indicated generally by the reference over the roof portion 21 of the upper auxiliary nuneral 6 where a standard grate 7 supported 100 central tank 20 for discharge through the flue on mounting lugs 8 on the main tanks 2, 3, 4 gas exit 13 defined between apair of spaced may be sited. A suitable water inlet connec- apart side bridging plates 28,29 welded to the tion 9 and outlet connection 10 are provided. rear tank 2 and respective main side tanks A plurality of additional tanks connected to 3,4 and a rear bridging plate 30 welded to one or more of the main tanks project into 105 the rear tank 2 and the side bridging plates the conbustion gas flue enclosure and abut 28,29.

against the front plate 5 to define in this case It will be noted that the roof portion 21 of two combustion gas passageways 11 through the upper auxiliary central tank 20 is in this which combustion gases are led from a com- case of inverted V-shape and extends down- mon inlet 12 adjacent a firebed to a common 110 wardly from a central apex 31.The advantage discharge outlet 13 to an exhaust flue (not of having an apex roof portion is to direct shown). In this case the inlet 12 is centrally combustion gases rising from the second ver disposed and each of the passageways 11 tical rising legs into the flue gas exit 13 and includes successively rising and failing legs also to facilitate cleaning.

through which the gases are led. Gases in 115 An inlet additional tank 35 extends between each passageway 11 are directed at least par- and bridges the main side tanks 3,4 below tially across the flue enclosure between the the front plate 5 and is spaced-apart from the main side tanks 3A to follow a substantially main rear tank 2 to define therewith an inlet tortuous path for heat transfer to the main combustion gas opening 31 through which and additional tanks. It will be noted that in 120 gases and flames pass into the combustion this case the side tanks 3,4 project forwardly gas inlet 9 to the flue gas passageways. In of all of the additional tanks. this case the. inlet additional tank 35 is sub The additional tanks comprises a pair of in- stantially wedge-shaped in transverse cross let auxiliary side tanks 15,16 each connected section and comprises a rearwardly and to the main rear tank 2 and respective side 125 downwardly extending top wall 36, a pair of tanks 3A and being spaced-apart to define depending side walls 37 which extend sub therebetween a common substantially centrally stantially parallel to the main rear tank 3 and a disposed inlet rising leg 17 of the passagerearwardly and upwardly extending bottom ways 11. Each auxiliary inlet side tank 15,16 wall 38. The bottom wall 38 is inclined rear- is substantially L-shaped and includes a lower 130 wardly upwardly for directing combustion 4 GB2192049A 4 gases and flames into the flue gas passage- each passageway 11, two gaps which are off way. set between the main side tanks. The lateral Retaining means for the front plate 5 is in offset of the gaps results in the gases being this case provided by a front mounting directed across the flue enclosure in each bracket 40 bridging the side tanks 3,4 adja- 70 passageway 11 to follow a substantially tortu cent the bridging plates 28,29. The mounting ous path.

bracket 40 is angle-shaped and includes a It will be appreciated that the tortuous com downwardly extending arm 41 and an in- bustion gas passageway just described allows wardly extending arm 42. In use, an upper for especially good heat transfer while still al- edge 43 of the front plate 5 is inserted be- 75 [owing the heat transfer surfaces to be easily hind the arm 41 and, the lower edge of the cleaned, on removal of the front plate 5.

front plate 5 resting on the top wall 36 of the It has been found that the inlet additional inlet additional tank 30, as will be particularly tank 35 allows particularly good heat transfer apparent from Fig. 4. The front plate 5 is to be achieved as it is located adjacent the formed with a centrally disposed handle 44. 80 firebed and is licked by both flame and gases A damper 45 is used to adjust the width of rising from a firebed.

the discharge outlet 13 and hence the rate of Referring to Figs. 5 and 6 there is illustrated combustion and flow of combustion gases a dual purpose tool 47 for use with the boiler through the flue gas passageway 11. The described above with reference to Figs. 1 to damper 45 is supported on the bridging plates 85 4. The tool 47 comprises a substantially rectil 28,29,30 and the bracket 40 and includes a inear plate 48 at one end of a handle 49. A downwardly extending handle 46. cut-out slot 50 is formed in the plate 48 and In use, when a fire is lit on the grate 7 the is sized to accommodate both the handle 46 combustion gases pass through the combus- of the damper 45 and the handle 44 of the tion gas passageways 11 as indicated by the 90 removable front plate 5 of the boiler so that arrows in Figs. 3 and 4. The combustion the tool can be used for adjusting the damper gases first rise up from the firebed enclosure or for removal of the front plate 5. As will be and impinge against the bottom wall 38 of the particularly apparent from Fig. 6 the tool 47 inlet auxiliary tank 30 and are directed up- may also be used for cleaning the heat ex wardly and against the rear tank 2. The gases 95 change surfaces of the boiler, the plate 48 then impinge against the lower portions 18 of being sized to allow it to be easily inserted the auxiliary side tanks 15,16 and are directed and withdrawn from the various legs of the into the central inlet rising leg 17 of the flue flue gas passageways.

gas passageway 11 where they impinge Referring to Fig. 7 there is illustrated a fur against the upper portions 19 of the auxiliary 100 ther construction of wrap-around back boiler side tanks 15,16. At the upper end of the indicated generally by the reference numeral inlet leg 17 of the passageway the gases are 55. This wrap-around back boiler 55 is of directed against the roof portion 21 of the similar construction to the wrap-around back upper auxiliary central tank 20 and are turned boiler illustrated in Figs. 1 to 6 and parts simi through substantially 180' and pass down the 105 lar to those described with reference to these intermediate failing legs 24,25 of the passage- drawings are identified by the same reference ways in which they impinge against the side numerals. In this case the roof portion 21 of portions 22,23 of the upper auxiliary central the upper central auxiliary tank 20 is flat. This tank 20 and the upper portions 19 of the provides a boiler of slightly simpler and auxiliary side tanks 15,16. At the lower end 110 cheaper construction. Instead of bridging of the intermediate failing legs 24,25 the plates a flue gas exit 56 is defined by a fur gases are directed against the lower portions ther pair of upper auxiliary side tanks 57,58 18 of the auxiliary side tanks 15,16 and are connected respectively to the side tanks 3 again turned through substantially 180 to rise and 4 and the rear tank 2. The use of the through the second vertical rising legs 26, 27 115 upper auxiliary side tanks 57, 58 leads to a in which the gases impinge against the side slightly more complex construction of boiler portions 22, 23 of the upper auxiliary central however improved heat transfer may be tank 20 and the main side tanks 3,4 of the achieved.

boiler At the upper end of the second vertical Referring to Fig. 8 there is illustrated a con rising legs 26,27 the gases are again turned 120 struction of boiler 60 according to the inven through substantially 90 by the bridging tion which is very similar to the wrap-around plates 28,29 and impinge against the roof back boiler described above with reference to portion 21 of the upper auxiliary central tank Figs. 1 to 6 andlikeparts are identified by the before discharge through the exhaust flue same reference numerals. In this embodiment exit 13. 125 two wedge-shaped upper side auxiliary tanks It will be noted that both the upper portions 61 and 62 are connected to the side tanks 3 19 of the auxiliary side tanks 15,16 andthe and 4 respectively and form a flue exit indi side portions 22,23 of the upper auxiliary cen- cated generally by the reference numeral 63.

tral tank 20 are spaced-apart from the respec- These additional tanks 61, 62 provide for im tive main side tanks 3,4 to provide, within 130 proved heat transfer however this is at the GB2192049A 5 expense of a slightly more complex construc- zontal additional tank 83 may be of inverted tion. It will also be noted that the roof portion V-shape. In addition, instead of tanks one or 21 of the uppercentral auxiliary tank and the more of the bridging members may be pro lower side auxiliary tanks 18 are inclined upvided by removable plates, firebricks, or the wardly at a larger angle than in the case of 70 like. Similar comments apply to the various the boiler of Figs. 1 to 6. This assists in other constructions of boilers described cleaning and in directing gases into the flue above.

gas passageways 11. Referring to Fig. 10 there is illustrated a Referring to Fig. 9 there is illustrated further construction of wrap- around back another boiler according to the invention indi- 75 boiler indicated generally by the reference cated generally by the reference numeral numeral 70.The boiler 70 is of similar con 65.The boiler 65 is again of similar construc- struction to the boiler described above with tion to the boiler described above with refer- reference to Figs. 1 to 4 and like parts are ence to Figs. 1 to 6 and like parts are as- assigned the same reference numerals. In this signed the same reference numerals. In this 80 case there are again two combustion gas case the roof portion 21 of the upper central passageways 71,72 through which the gases auxiliary tank 20 is flat and the lower portions are led from separate offset centrally disposed 18 of the inlet auxiliary side tanks 15,16 ex- inlets 73,74 to separate offset discharge out tend at a 90 angle from the respective main lets 75,76. In this case the upper auxiliary side tanks 3,4. This boiler is of particularly 85 central tank 21 includes an additional centrally simple construction however there is some sa- disposed depending portion 77 which extends crifice in both heat transfer, ease of cleaning into the space defined between the auxiliary and draught over the boiler of Figs. 1 to 6. side tanks 15,16 to define first rising legs of At the lower end of the first falling legs each of the passageway 71,72. It will be 106,107 the combustion gases impinge 90 noted that the lowermost end of the central against the horizontal additional tanks portion 77 of the auxiliary tank is cut-away to 101,102 and are directed upwardly into a a substantially V-shape to direct combustion second rising legs 108,109 defined between gases rising from a firebed into the first inlet respective side additional tanks 94,95 and rising legs of the passageway 71,72. The 98,99. At the upper end of the second rising 95 flow of gases through the passageways 71,72 legs 108,109 the combustion gases again imis controlled by a damper plate 80 which is pinge against the upper horizontal additional slidably movablein the direction of the arrow R tank 103 and are directed downwardly into between the main side tanks 3A in a track second failing legs 110, 111 defined between defined by a pair of spaced- apart guide rails the side additional tanks 93,94 and 99,100 100 79,80. The damper 78 is formed with two respectively. At the lower end of the second rectilinear slots 81,82 which are moved, on falling leg 110, 111 the combustion gases im- operation of the damper, into and out of pinge against the lower horizontal additional alignment with the outlet openings 75,76 of tanks 102,103 and are directed upwardly into the passageway 71,72 to control the flow of final third rising legs 112,113 at the upper 105 gases.

end of which they impinge against the respec- It will be noted that in this case the front tive bridging plates 28,29 before discharge plate 5 is formed with two mounting holes 83 through the flue gas exit 13. for engagement with mounting bolts 84 pro Because of space limitations it will be noted jecting forwardly from the depending side por that the side additional tanks 93 to 100 and 110 tion 22,23 of the upper auxiliary tank.

the legs of the combustion gas passageway Referring to Fig. 11 there is illustrated are substantially narrower than the corre- another boiler indicated generally by the refer- sponding tanks and legs of the boiler de- - ence numeral 85, This wrap- around back scribed above with reference to Figs. 1 to 6. boiler 85 is of similar construction to the The boiler of Fig. 10 however provides parti- 115 boiler of Fig. 10 and parts similar to those cularly good heat transfer efficiency. Because described with reference to Fig. 10 are identi of space limitation such an arrangement of fled by the same reference numerals. In this tanks may be suitable only for larger size - case the two combustion gas passageways boilers. 71,72 have a common inlet 86 leading to a Many modifications on the particular em- 120 common first rising leg at the upper end of bodiment of the boiler shown in Fig, 12 will which the gases are separated into two first be readily appreciated. For example additional falling legs by a deflector plate 87 which pro rising and falling legs may be incorporated by jects downwardly from the roof portion 21 of providing additional tanks and bridging mem- the upper central auxiliary tank 20.

bers. It will also be appreciated that while the 125 Referring to Fig. 12 there is illustrated bridging members have been described as another boiler according to the invention indi formed from horizontally disposed additional cated generally by the reference numeral 90.

tanks such tanks may be inclined upwardly or The boiler 90 is of similar construction to the downwardly with respect to the side tanks. It boiler described above with reference to Figs.

is particularly envisaged that the upper hori- 130 1 to 6 and again like parts are assigned the 6 GB2192049A 6 same reference numerals. The main difference In use, combustion gases and flames from between this boiler and the boiler described the firebed are drawn towards the side inlet above with reference to Figs. 1 to 6 is that openings and pass up thefirst rising legs there are two additional successive failing and 127,128 of the combustion gas passageway rising legs adjacent each main side tank 3A 70 and then down the first failing legs 131,132 through which the combustion gases are led and up the final common rising leg 124 before before discharge through the flue gas exit 13. discharge to an exhaust gas flue as indicated One way of arranging such passageways is by the arrows in Fig. 13.

illustrated in Fig. 12. In this case eight addi- Referring to Fig. 14 there is illustrated tional tanks 93 to 100 are provided, each exanother boiler according to the invention indi tending substantially parallel with the main cated generally by the reference numeral 140.

side tanks 3A Bridging means between alter- The boiler 140 is of similar construction to nate tanks is in this case provided by three the boiler described above with reference to horizontally disposed additional tanks Fig. 13 and like parts are assigned the same 101,102,103, the tanks 101 and 102 being 80 reference numerals. In this case the lower interconnected with the additional tanks 94 to central auxiliary tank 121 includes a central 96,97 and 99 respectively and to the respec- portion 141 which extends upwardly into the tive sidetanks 3A while the horizontal addispace defined between the downwardly de tional tank 103 is interconnected with the side pending portions 130 of the auxiliary side additional- tanks 93,95,98 and 100 and with 85 tanks 122,123 so that instead of a common the rear tank 2. Combustion gases from a final rising leg, two separate rising legs firebed are led into the combustion gas pass- 142,143 are formed having discharge outlets ageway through a centrally disposed inlet 144. A damper plate 145 is slidably movable opening 104 to a first central rising leg 105 in the direction of the arrows S in tracks de- of the passageway. At the upper end ofthe 90 fined between a pair of facing channel guide first rising leg 105 the combustion gases im- members 146 to adjust the flow of gases pinge against the horizontal additional tank through the passageways. It will be noted that 103 and are directed downwardly into respec- to assist in directing combustion gases into tive first falling legs 106,107 defined respec- the passageways the lower bridging portion tively between the side additional tanks 95,96 95 125 of thelower central auxiliary tank 121 is and 97,98 respectively. substantially V-shaped in transverse cross sec Referring to Fig. 13 there is illustrated tion. In this case, the removable front plate 5 another boiler according to the invention indi- is formed with two mounting holes 147 which cated generally by the reference numeral 120. engage with complementary mounting bolts This boiler 120 is again of similar construction 100 148 carried by the side portions 126 of the to the boiler described above with reference lower auxiliary tank 121.

to Figs. 1 to 6 and like parts are assigned the Referring to Fig. 15 there is illustrated same reference numerals. In this case the aux- another boiler according to the invention indi iliary side tanks and upper central auxiliary cated generally by the reference numeral 150.

tank of the boiler of Figs. 1 to 6 are, as it 105 The boiler 150 is of similar construction to were, turned upside-down so that in this case the boiler described above with reference to there is provided a lower central auxiliary tank Fig. 13 and like parts are again assigned the 121 and two upper side auxiliary tanks same reference numerals. In this case a 122,123 which are spaced-apart to define deflector plate 151 projects upwardly from the therebetween a centrally disposed final rising 110 bridging portion 125 of the lower auxiliary leg 124 through which combustion gases are tank 121 into the final rising leg 124 defined led before discharge through the discharge between the downwardly depending side por outlet 13 to an exhaust gas flue. tions 130 of the upper side auxiliary tanks The lower central auxiliary tank 121 is con- 121,123 to direct gases upwardly into the nected to the back tank 2 and includes a 115 final rising leg. The bridging portion 125 is lower bridging portion 125 and a pair of upagain of V-shape to direct combustion gases wardly extending side portions 126 which de- from the firebed into the combustion gas fine, together with a respective main side tank passageways. The common outlet 13 from 3,4, first rising legs 127,128 of the combus- the combustion gas passageways is in this tion gas passageways, Each upper auxiliary 120 case closable by a damper plate 152 which is side tank 122,123 is of substantially inverted slidably movable in the direction of the arrow L-shape and includes an upper sidewardly ex- R between the main side tanks 3,4 in a guide tending portion 129 extending over the rising track defined by a pair of facing rails leg 127,128 and a downwardly depending 153,154. The damper plate 152 includes a portion 130 which extends downwardly to- 125 central aperture 155 which is of the same size wards the bridging portion 125 of the lower and shape as the discharge outlet 13 from the central auxiliary tank 121 to define, together combustion gas passageways to control the with the side portion 126 of the lower aux- flow of gases through the outlet.

iliary tank 121, respective first falling legs 131 Referring to Fig. 16 there is illustrated a and 132 for combustion gases. 130wrap-around back boiler indicated generally by 7 GB2192049A 7 the reference numeral 160 in which parts simi- substantially horizontal.

lar to those described with reference to the A pair of side auxiliary tanks 203 and 204 previous drawings are identified by the same are connected respectively to the side tanks 3 reference numerals. In this embodiment there and 4 andthe rear tank 2. The side auxiliary is provided a lower offset inclined auxiliary 70 tanks 203 and 204 are mounted above the tank 161 connected to and extending from a lower central auxiliary tank 202 to allow the main side tank 4 and spaced-apart from a passage of the flue gases therebetween. A main side tank 3. Mounted above the lower further upper central auxiliary tank 205 is offset inclined auxiliary tank 161 is an inter- mounted above the side auxiliary tanks 203 mediate vertical auxiliary tank 162 connected 75 and 204. A pair of upper side auxiliary tanks to the main rear tank 2 and the lower offset 206 and 207 are mounted above the upper inclined auxiliary tank 161. Above and spacedcentral auxiliary tank 206 to define a flue exit apart from the intermediate vertical auxiliary 208. The upper side auxiliary tanks 206 and tank 162 is an upper offsetauxiliary tank 163 207 are each respectively connected to the connected to the main side tank 3 and por80 side tanks 3 and 4 and the rear tank 2 and tions of the main rear tank 2. The upper off- against the front plate 5.

set auxiliary tank 163 communicates with the In use, when a fire is lit in the firebed enclo further intermediate vertical auxiliary tank 164. sure, the combustion gases rise as shown by There is thus formed by the two intermediate the arrows in Fig. 18. The combustion gases vertical auxiliary tanks 162 and 164 the lower 85 first rise up from the firebed enclosure 7 and offset inclined auxiliary tank 161, the upper impinge against the bottom of the inlet aux offset auxiliary tank 163, and the main two iliary tank 35 and are directed upwardly and main side tanks 3 and 4, a rising leg 165, a against the rear tank 2. The flue gases then failing leg 126 and a further rising leg 167 for impinge against the lower central auxiliary tank exhaust flue gases, the passage of the flue 90 202 and are forced outwards between the gases being illustrated by the arrows. One lower auxiliary tank 202 and the side tanks 3 particular advantage of this embodiment is and 4. The rising gases then impinge against that there will be relatively good heat transfer the side auxiliary tanks 203 and 204 and are in a small compact boiler. forced to pass between them when on rising, Referring to Fig. 17 there is illustrated a 95 they encounter the upper central auxiliary tank further construction of wrap-around back 205 and are again diverted side- ways be boiler indicated generally by the reference tween the said upper central auxiliary tank numeral 180 in which parts similar to those 155 and the side tanks 3 and 4. The gases described with reference to Fig. 16 are identi- then are directed by the upper sideauxiliary fied, by the same reference numerals. Again, 100 tanks 206 and 207 through the flue exit 208.

there is a single combustion gas passageway. Referring to Fig. 19 there is illustrated In this embodiment there is a lower offset another boiler according to the invention simi horizontal auxiliary tank 181 and four interme- lar to the boiler described above with refer diate vertical auxiliary tanks 182,183,184 and ence to Fig. 18 and like parts are assigned 185 alternatively connected to the lower off- 105 the same reference numerals. In this' case the set horizontal auxiliary tank 181 and an upper combustion gas passageway includes five in offset auxiliary tank 186, thus forming a rising terconnected legs which extend successively leg 187, a failing leg 188, a rising leg 189, a sidewardly towards and away from the main failing leg 190 and a final rising leg 191. side tanks 3,4. The interconnected legs of the Essentially this the same construction as the 110 passageway are in this case defined by six boiler of Fig. 16 except that instead of three auxiliary side tanks 211 to 216, three legs or passes of the flues gases in a vertical 211,213,215 of which are connected to the direction through the boiler there are now five main side tank 4 and project inwardly up legs, thus, more efficient heat transfer will be wardly therefrom towards but spaced-apart achieved. 115 from the other main side tank 3. The other Referring to Fig. 18 there is illustrated a three of the auxiliary side tanks 212,214,216 boiler according to another embodiment of the project inwardly downwardly from the main invention indicated generally by the reference side tank 3 towards but spaced-apart from numeral 200. The boiler 200 is of similar con- the other main side tank 4. It will be noted struction to the boiler described above with 120 that alternate tanks are spaced-apart along a reference to Figs. 1 to 6 and like parts-are vertical axis to facilitate flow of gases be assigned the same reference numerals. In this tween the tanks. The advantage of this con embodiment the gases are led sidewardly struction ofboilerisin providing a boiler with a across the flue enclosure respectively towards relatively high heat transfer efficiency and and away from the respectiveside tanks 3,4. 125 which can be easily cleaned. The particular A lower central auxiliary tank 202 is arrangement of the tanks facilitates cleaning.

mounted above the inlet auxiliary tank 35 and Referring to Fig. 20 there is illustrated is connected to the rear tank 2. The lower another boiler according to the invention indi central auxiliary tank 202 is spaced-apart from cated generally by the reference numeral 220.

the side tanks 3 and 4 and in this case is 130 The boiler 220 is of similar construction to 8 GB2192049A - 8 the boiler described above with reference to tion but other constructions may be used.

Fig. 19 and like parts are assigned the same

Claims (24)

1. reference numerals. In this case there are five CLAIMS additional tanks,

   three of which 211,213,215 1. A wrap-around back boiler comprising:

   are connected to the main side tank 4, and 70 a main rear tank; two of which 212,214 are connected to the a pair of outwardly directed main side tanks main side tank 3. The additional side tanks connected to the rear tank and defining there 212, 214 in this case project inwardly up- with a channel-shaped firebed and flue enclo wardly from the main side tank 3 towards the sure; main side tank 4. The advantage of this con- 75 a plurality of additional tanks connected to struction of boiler is in possibly improved heat at least one of the main tanks and extending transfer over the boiler of Fig. 19 as the ar- into the enclosure; rangement of the tanks causes the gases to and a front bridging member extending be impinge against substantially all of the heat tween at least two of the additional tanks; transfer surface leading to a high heat transfer 80 the main tanks, additional tanks and front efficiency. bridging member together defining a tortuous Referring to Fig. 21 there is illustrated flue gas passageway which extends from an another boiler according to the invention indi- inlet adjacent a firebed to a discharge outlet cated generally by the reference numeral 230 to an exhaust flue, which is of similar construction to the boiler 85 the front bridging member being removable described above with reference to Fig. 20 and to leave a front opening allowing access to like parts are assigned the same reference the passageway for cleaning, numerals. In this case the auxiliary side tanks the additional tanks being so arranged that 213,215 are inclined inwardly downwardly to- in use, the flue gases travelling along the wards the main side tank 3 and the auxiliary 90 passageway are constrained to move laterally side tanks 212,214,216 are inclined inwardly between the main side tanks.

   upwardly towards the other main side tank 4.
2. 2. A boiler as claimed in Claim 1 inwhich The advantage of this construction of boiler the front bridging member comprises a remo is in that it is of a relatively simple construc- vable front plate for the combustion gas pass tion and can be easily cleaned while still pro- 95 ageway.

   viding relatively good heat transfer efficiency.
3. 3. A boiler as claimed in Claim 1 or Claim 2 It will be appreciated that in the case where which combustion gas passageway includes at a lower auxiliary tank such as a tank 35 is least three interconnected successively rising used this may extend forwardly into the enclo- and failing legs.

   sure from, and be connected with, the rear 100
4. 4. A boiler as claimed in any of Claims 1 to tank. The particular advantage however, of 3 in which the boiler includes two combustion having a spacing between the rear tank and gas passageways, each having at least three such an additional tank is in providing a rela- interconnected successively rising and failing tively large heat transfer surface as close as legs.

   possible to the hottest point of the firebed, all 105
5. 5. A boiler as claimed in claim 4 in which the surfaces of which can be licked by the the combustion gas passageways extend from flames and combustion gases. It also has the a common inlet.

   advantage of providing a support for the re-
6. 6. A boiler as claimed in claim 5 in which movable front plate, in use. the inlet is substantially centrally disposed be- lt will be appreciated that instead of tanks 110 tween the main side tanks.

   in certain instances fins or deflector means,
7. 7. A boiler as claimed in claim 5 or 6 in such as plates, may be used. It will also be which the passageways include a common appreciated that the removal of the front plate central rising leg and successively rising and will facilitate the cleaning of the boiler as is falling legs on each side of the central rising well known. Additionally, instead of a front 115 leg.

   plate a conventional hinged door may be
8. 8. A boiler as claimed in claim 7 in which used. Such a door may incorporate a viewing each passageway includes two successively window if desired. rising and failing legs on each side of the It will also, be appreciated that any or all of common central rising leg.

   the additional tanks need not necessarily be 120
9. 9. A boiler as claimed in any of claims 5 to connected to one of the main tanks. For 8 comprising a pair of inlet auxiliary side tanks example, while such constructions of boiler connected to the rear tank and respective side may not be as easily cleaned and may have tanks and spaced-apart to define there reduced heat transfer efficiency any or all of between the substantially central inlet rising the additional tanks could be connected to the 125 leg, and an upper auxiliary central tank con- main tanks through auxiliary tanks such as a nected to the rear tank and extending down header tank extending between the main side wardly between the inlet side auxiliary tanks tanks. and each main side tank to form, on each The boilers according to the present inven- side of the inlet rising leg, a successive inter- tion are of mild steel plate welded construc- 130 mediate falling leg and an outlet rising leg for 9 GB2192049A 9 combustion gases. which each bridging member comprises an up
10. 10. A boiler as claimed in claim 9 in which per bridging tank connected to the main rear each inlet auxiliary side tank initially extends tank and a respective side tank.

    inwardly from a main side tank and is then 25. A boiler as claimed in claim 24 in which directed upwardly. 70 each bridging tank is substantially wedge
11. 11. A boiler as claimed in claim 10 in which shaped in transverse cross section.

    each inlet auxiliary side tank is initially inclined 26. A boiler as claimed in any of claims 23 upwardly from a main side tank. to 25 in which the combustion gas passage
12. 12. A boiler as claimed in claim 10 in which way includes four successively rising and fall- each inlet auxiliary side tank initially extends 75 ing legs on each side of a central rising leg.

    inwardly substantially at right angles to the 27. A boiler as claimed in any of claims 1 main side tank to which it is connected. to 4 in which the inlet to the or each combus
13. 13. A boiler as claimed in claim 11 or 12 in tion gas passageway is provided by an inlet which each inlet auxiliary tank is then directed opening adjacent a main side tank.

    upwardly substantially parallel to a main side 80 28. A boiler as claimed in claim 1 or 2 in tank. which the combustion gas flue passageway in 14. A boiler as claimed in any of claims 9 cludes at least three interconnected legs which to 13 in which the upper auxiliary central tank extend successively sidewardly, at least par includes a top roof portion extending over the tially across the enclosure, towards and away first rising leg of the combustion gas passage- 85 from the main side tanks.

    way. 29. A boiler as claimed in-claim 28 includ 15. A boiler as claimed in claim 14 in which ing a lower additional tank connected to the the top roof portion includes a substantially main rear tank and spaced- apart from at least flat portion extending forwardly substantially at one main side tank to define an inlet opening right angles to the main rear tank. 90 for combustion gases, at least one intermedi 16. A boiler as claimed in claim 14 in which ate additional tank above the lower tank and the top roof portion includes a substantially connected to the rear tank to define, together inverted V-shaped portion having a substan- with the lower additional tank a sidewardly tially centrally disposed apex. extending leg of the combustion gas passage- 17. A boiler as claimed in any of claims 9 95 way, and an upper additional tank connected to 16 in which the upper auxiliary central tank to the rear tank and above the intermediate includes a pair of depending side portions ex- tank to define therewith another sidewardly tending downwardly between the inlet side extending leg of the combustion gas passage auxiliary tanks and each main side tank to way.

    form, on each side of the inlet rising leg, a 100 30. A boiler as claimed in claim 29 in which successive intermediate failing leg and an out- the additional tanks are substantially parallel let rising leg for combustion gases in each with each other.

    passageway. 3 1. A boiler as claimed in claim 29 or 30 in 18. A boiler as claimed in any of claims 2 which at least some of the additional tanks to 17 including an inlet additional tank, bridg- 105 are inclined inwardly upwardly with respect to ing the main side tanks adjacent the front the main side tanks.

    plate. 32. A boiler as claimed in any of claims 29 19. A boiler as claimed in claim 18 in which to 31 in which at least some of the additional the inlet additional tank includes a rearwardly tanks are inclined inwardly downwardly with and downwardly extendingIop wall. 110 respect to the main side tanks.

    20. A boiler as claimed in claim 18 or 19 in 33. A boiler as claimed in claim 28 corn which the inlet additional tank includes a rear- prising a lower central auxiliary tank connected wardly extending bottom wall. to the rear tank and spaced-apart from each 21. A boiler as claimed in any preceding main side tank to define an opening through claim comprising a pair of upper side auxiliary 115 which combustion gases pass, a pair of inter bridging members extending from a respective mediate side auxiliary tanks above the lower side tank and the rear tank and being spacedcentral auxiliary tank and connected respec apart to define therebetween the discharge tively to the main side tanks and spaced-apart outlet to an exhaust gas flue. to define therebetween a central opening for 22. A boiler as claimed in claim 21 corn- 120 flue gases and an upper central auxiliary tank prising a rear auxiliary bridging member ex- above the side auxiliary tanks connected to tending from the main rear tank to define, the rear tank and spaced-apart from the main together with the side auxiliary bridging mem- side tanks to define an opening through which bers the discharge outlet to an exhaust gas gases rising from the central opening between flue. 125 the side auxiliary tanks pass.

    23. A boiler as claimed in claim 21 or 22 in 34, A boiler as claimed in any of claims 28 which each bridging member comprises a to 33 including an inlet additional tank, bridg bridging plate extending from a respective ing the side tanks adjacent the front plate.

    main tank. 35. A boiler as claimed in claim 34 in which 24. A boiler as claimed in claim 21 or 22 in 130 the inlet additional tank is rearwardly and up- GB2192049A 10 wardly inclined. the front bridging member being removable 36. A boiler as claimed in any of claims 2 to leave a front opening allowing access to to 35 including retaining means for the front the passageway for cleaning, plate. the additional tanks being so arranged that 37. A boiler as claimed in claim 36 in which 70 in use, the flue gases travelling along the the retaining means comprises a retaining passageway are constrained to move succes bracket bridging the side tanks adjacent the sively, sidewardly, at least partially across the discharge outlet. enclosure towards and away from the main 38. A boiler as claimed in claim 37 in which side tanks.

    the retaining bracket comprises an angle 75 2. A boiler as claimed in claim 1 in which bracket having a downwardly extending first the front bridging member comprises a remo arm and an interconnected inwardly extending vable front plate for the combustion gas pass second arm, a top edge of the front plate ageway.

    being retained, in use behind the first arm. 3. A boiler as claimed in claim 1 or claim 2 39. A boiler as claimed in any of claims 18 80 in which the boiler includes two combustion to 27 or 35 in which the removable front gas passageways.

    plate is supported, in use, on the inlet addi- 4. A boiler as claimed in any preceding tional tank. claim comprising a pair of upper side auxiliary 40. A boiler as claimed in any of claims 2 bridging members extending from a respective to 39 in which the additional tanks abut, in 85 side tank and the rear tank and being spaced use against the front plate. apart to define therebetween the discharge 41. A boiler as claimed in any preceding outlet to an exhaust gas flue.

    claim including a damper for the discharge 5. A boiler as claimed in claim 4 comprising outlet from the combustion gas passageway. a rear auxiliary bridging member extending 42. A boiler substantially as hereinbefore 90 from the main rear tank to define, together described with reference to Figs. 1 to 17. with the side auxiliary bridging members the 43. A boiler substantially as hereinbefore discharge outlet to an exhaust gas flue.

    described with reference to Figs. 18 to 21. 6. A boiler as claimed in claim 4 or 5 in 44. A tool for cleaning a back boiler having which each bridging member comprises a a handle and a cleaning head wherein the 95 bridging plate extending from a respective handle or head includes means for operating a main tank.

    damper and/or a removable front plate for the 7. A boiler as claimed in claim 4 or 5 in boiler. which each bridging member comprises an up 45. A tool as claimed in claim 44 in which per bridging tank connected to the main rear a cut-out slot is provided in the cleaning head 100 tank and a respective side tank.

    for engaging with a complementary lug on a 8. A boiler as claimed in claim 7 in which damper and/or a removable front plate. each bridging tank is substantially wedge 46. A hand tool substantially as hereinbe- shaped in transverse cross section.

    fore described with reference to Figs. 5 and 9. A boiler as claimed in any of claims 1 to 6. 105 3 in which the inlet to the or each combustion gas passageway is provided by an inlet open ing adjacent a main side tank.

    CLAIMS 10. A boiler as claimed in claim 1 or 2 in Amendments to the claims have been filed, which the combustion gas flue passageway in- and have the following effect: 110 cludes at least three interconnected legs which Claims 1 to 46 above have been deleted. extend successively sidewardly, at least par New claims have been filed as follows: tially across the enclosure, towards and away 1. A wrap-around back boiler comprising: from the main side tanks.

    a main rear tank; 11. A boiler as claimed in claim 10 includ- a pair of outwardly directed main side tanks 115 ing a lower additional tank connected to the connected to the rear tank and defining there- main rear tank and spaced- apart from at least with a channel-shaped firebed and flue enclo- one main side tank to define an inlet opening sure; for combustion gases, at least one intermedi a plurality of additional tanks connected to ate additional tank above the lower tank and at least one of the main tanks amd extending 120 connected to the rear tank to define, together into the enclosure; at least two of the addi- with the lower additional tank a sidewardly tional tanks being connected to and extending extending leg of the combustion gas passage generally inwardly from the main side tanks; way, and an upper additional tank connected and a front bridging member extending be- to the rear tank and above the intermediate tween at least two of the additional tanks; 125 tank to define therewith another sidewardly the main tanks, additional tanks and front extending leg of the combustion gas passage bridging member together definimg a tortuous way.

    flue gas passageway which extends from an 12. A boiler as claimed in claim 11 in which inlet adjacent a firebed to a discharge outlet the additional tanks are substantially parallel leading to an exhaust flue, - 130 with each other.

    GB2192049A 13. A boiler as claimed in claim 11 or 12 in which at least some of the additional tanks are inclined inwardly upwardly with respect to the main side tanks.
14. 14. A boiler as claimed in any of claims 11 to 13 in which at least some of the additional tanks are inclined inwardly downwardly with respect to the main side tanks.
15. 15. A boiler as claimed in Claim 10 in which the additional tanks include a lower central auxiliary tank connected to the rear tank and spaced-apart from each main side tank to define an opening through which combustion gases pass, a pair of intermediate side auxiliary tanks above the lower central auxiliary tank and connected respectively to the main side tanks and spaced-apart to define therebetween a central opening for flue gases and an upper central auxiliary tank above the side auxiliary tanks connected to the rear tank and spaced-apart from the main side tanks to define an opening through which gases rising from the central opening between the side auxiliary tanks pass. 25
16. 16. A boiler as claimed in any of claims 10 to 15 including an inlet additional tank, bridging the side tanks adjacent the front plate.
17. 17. A boiler as claimed in claim 16 in which the inlet additional tank is rearwardly and up- wardly inclined.
18. 18. A boiler as claimed in any of claims 2 to 17 including retaining means for the front plate.
19. 19. A boiler as claimed in claim 18 in which the retaining means comprises a retaining bracket bridging the side tanks adjacent the discharge outlet.
20. 20. A boiler as claimed in claim 19 in which the retaining bracket comprises an angle bracket having a downwardly extending first arm and an interconnected inwardly extending second arm, a top edge of the front plate being retained, in use behind the first arm.
21. 21. A boiler as claimed in any of claims 4 to 9 or 17 in which the removable front plate is supported, in use, on the inlet additional tank.
22. 22. A boiler as claimed in any of claims 2 to 21 in which the additional tanks abut, in use against the front plate.
23. 23. A boiler as claimed in any preceding claim including a damper for the discharge outlet from the combustion gas passageway.
24. 24. A boiler substantially as hereinbefore described with reference to Figs. 5 to 8.

    Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampion Buildings, London, WC2A 1 AY, from which copies may. be obtained.