GB2189311A - Collecting condensate from gas boilers - Google Patents

Abstract

Condensate is discharged from a condensing type gas-fired appliance such as a boiler to a drainage point by means such as the siphons 11 or 21 adapted to commence discharge of the condensate from a receptacle 12 or 51 to the drainage point only when the collected condensate has risen to a predetermined uppermost level and to continue discharge of the condensate thereafter only until the collected condensate has fallen to a predetermined lowermost level. A trickle of condensate which may freeze and block the drainage pipe is thereby avoided. <IMAGE>

Description

SPECIFICATION Apparatus for discharging condensate from a condensing type gas-fired appliance The present invention relates to apparatus for discharging condensate from a condensing type gas-fired appliance such as a gas-fired boiler.

During operation of a condensing type gas-fired boiler water vapour contained in the exhaust gas is caused to condense out from the exhaust gas on the walls of the boiler heat exchanger.

In conventional boilers of thins type the condensate water is discharged undergravityto a receptacle such as a U-shaped collector pipe. This leads to a drainage point which may be in the form of a downwardly sloping drain pipe which discharges its contents into a soil stack or open gulley. In use the condensate trickles continuously along the drain pipeto the drain while condensate is being collected.

In sub-zero temperature conditions the trickle of condensate may freeze leading to a blockage forming in the drain pipe.

It is therefore an object of the present invention to provide apparatus enabling the condensate to be discharged in such a way that the likelihood of the condensate freezing in the drain pipe in sub-zero temperature conditions is greatly reduced.

According therefore to the present invention we provide apparatus for discharging condensate from a condensing type gas-fired applianceto a drainage point, the apparatus comprising a receptacle for receiving and collecting condensate discharged under gravity from the appliance and condensate discharge means adapted to commence discharge of the condensate from the receptacle to the drainage point onlywhen the collected condensate has risen to a predetermined uppermost level and to continue discharge of the condensate thereafter only until the collected condensate has fallen to a predetermined lowermost level.

In this way the condensate can be discharged in a concentrated surge at discrete intervals instead of a continuous trickle.

As a surge provides a greater volume flow of water and heat content in unit time than does a trickle there is a reduction in the risk ofthe water freezing in the drain pipe.

The preferred form of condensate discharge means comprises syphon means as this is the simplest and cheapest form of discharge device involving no moving parts. The syphon passage may incorporate a restrictorto promote the syphon action.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure lisa diagrammatic view of a conventional drainage system for discharging condensate from a condensing boiler, Figure2 is a longitudinal section through a drainage pipe in accordance with a first embodiment of the invention, Figure 3 is a section along the lines Ill-Ill of Figure 2, Figure 4 is a diagrnmmatic view of a second embodiment of the invention, and Figure 5is a diagrammatic view of a third embodiment of the invention.

Referring to the drawings, Figure 1 discloses the bottom half of a condensing boiler 1 comprising a sump 2 for collecting condensate discharging downwardly from the heat exchanger (not shown) in the top half of the boiler and a drainage duct 3 for receiving the condensate discharging downwardly from the sump 2 for dischargeto a soil stack (not shown) e.g. a drain.

The duct section adjoining the sump 2 is in the form of U 4which extends through a sidewall 5 of the boiler casing 6 and terminates in a downwardly sloping drain pipe 7 which discharges the condensate to a drain.

In use, condensate is continuously discharged to the sump 2 and then enters the duct 3 before being discharged from the pipe 7 in the form of a continuous trickle.

Referring to Figures 2 and 3 the drain pipe 7 shown has now been modified in accordance with the invention so that instead of the condensate being discharged as a trickle it is discharged as a surge at discrete intervals. To this end an apertured circular plate 10 is provided located intermediate the ends of the pipe 7, the plate 10 serving to block the bore of the pipe 3.

In addition a syphon in the form of an inverted U-tube 11 is provided to extend through the aperture and provide a communication between that portion 12 of the pipe 3 which lies uppermost of the plate 10 and that portion 13 of the pipe which lies lowermost ofthe plate 10.

Free flow of condensate between the portions 12 and 13 can therefore only take place by way of the syphon tybe 11, the arms 14 and 15 of which as shown terminate downwardly short of the internal surfaceofthe pipe 7.

In use, condensate entering the uppermost portion 12 of the pipe 7 collects therein as shown in Figure 2 and enters the uppermost arm of the syphon 11.

When the lever of the condensate in the arm 14 reaches a position enabling the condensate to flow overthe bend in the syphon, the head of liquid so formed causes the syphoning action to start and continue until the lever of the liquid in the arm 14 has fallen to a position enabling airto enterthe arm 14by way of its lowermost end 15. Atthis pointthe syphon effect is discontinued until the liquid has reached the required upper level once again. Mostoftheliquid which has collected in the uppermost portion 12 of the pipe 3 will therefore have been discharged into the lowermost portion 13 ofthe pipe 7 as a high-volume surge rather than as a trickle and thus the riskoffreezing is reduced.

An airvent 16 is provided inthewall ofthe uppermost pipe portion 12 to ensure that atmospheric air is availableto enterthe arm 14when the liquid level has dropped to its lowermost level and prevent the syphon effect from continuing to operate. Similarlythe diameter of the syphon 11 at the lowermost end 1 ofthe arm 14 is greaterthan the rest of the syphon tube 11 to permit easier access for air into the tube 11 thereby breaking the syphon effect.

Referring to Figure 4, here the duct3 shown in Figure 1 has been replaced by a tank 20 incorporating a syphon tube 21.The sump 2terminates in a vertically downwardly extending discharge pipe 22 which terminates within the tank 20.

The tank 20 is formed with a main compartment 23 into which the pipe 22 extends and an adjoining sub-compartment 24 separated from the main compartment 23 by an internal wall 25. The upper ends of both compartments are closed by a wall 26 through which the pipe 22 extends and from which the wall 25 is spaced.

The main compartment 23 comprises a lowermost chamber 27 formed by the base 28 of the tank, a vertical side wall 29, two further spaced vertical side walls arranged in the plane of the paperand adjoining the side wall 29 and the internal wall 25 which as shown extends upwardly from the base 28.

The main compartment 23 also forms an uppermost chamber 30 surmounting the lowermost chamber 27 and formed by avertical sidewall 31,thetwo adjacent vertical side walls common to those of the uppermost chamber and the internal wall 25. The sidewall 31 is located inwardly of the sidewall 29, there being a horizontal wall 32 which adjoins the walls 29 and 31. Thus the uppermost chamber is of reduced cross-sectional area compared to that ofthe lowermost chamber for pu rposes to be described.

The sub-compartment 24 is formed by the base 28, the internal wall 25, the vertical side walls common to the main com pa rtment gnd a furthervertical side wall 33 from which there extends outwardly a downwardly sloping drain pipe 34.

The syphon tube 21 isintheform of an inverted U having one arm 35 located in the main compartment 23 and anotherarm 36 having a generally vertical portion 37 located in the sub-compartment 24 and a downwardly sloping end portion 38 located in the drain pipe32,thetube 21 extending through an aperture in the internal wall 25. The bend in the tube 21 is arranged to be level with the uppermost chamber 30 for a purpose to be described. The internal diameterofthe arm 36 is restricted at39 by means of a restrictormemberandthistendsto promotethesyphon action.

In use, condensate entering the sump 2 is discharged to the lowermost chamber 27 ofthe compartment 23. As the lever of condensate within the chamber 27 rises the condensate enters the arm 35 of the syphon tube 21. Eventually the level of condensate reaches the uppermost chamber 30 and flows overthe bend in the syphon tube 21 to effect the syphoning action previously described. This action continues until the level of liquid falls to a point in the lowermost chamber enabling air to enter the lowermost end 40 of the arm 35 to discontinue the syphoning action.The reduced cross-sectional area ofthe uppermost chamber 30 compared to the lowermost chamber 27 causes the liquid level in uppermost chamber 27 to rise more rapidly than that in the uppermost chamber 30 so as to accelerate the rise of the liquid level in the arm 35 of the syphon tube 21 towards and over the bend.

In orderto ensure the access of airto the lowermost end 40 ofthe tube 21 the top wall 26 of the tank20 is provided with an airvent41.

The space between the side wall 25 and the top wall 26 forms an overflow 42 for liquid in the uppermost chamber 30.

Referring to Figure5 where parts similarto those shown in Figure 4 bear similar reference numerals, here the sump 2 has been completely dispensed with and the condensate is arranged to discharge directly from the heat exchanger shown schematically by 50 into a collectortank 51. In this case the collectortank 51 has three compartments 52,53 and 54.

The first compartment 52 which is arranged to receive the condensate has an opening 55 in its uppermost end and is otherwise formed by a base 56, a vertical outerwall 57, lying in the plane of the paper and two spaced vertical outer side walls (not shown) also common to the other compartments and a vertical innerwall 58 also common to the second compartment 53.

Theinnerwall 58 adjoins an outertopwall 59 at its uppermost end, which top wall 59 has a portion 60 which slopes downwardlytowards the opening 55 and serves as a drip tray to receive condensate from the heat exchanger 50 for supplyto the first compartment 52. As shown the internal wall 58 terminates short of the base 56 to form an opening 61 to permit the condensate to enterthesecond compartment 53.

The second compartment 53 is formed by the base 56, the internal wall 58, the two vertical sidewalls previously mentioned, a further internal wall 25 common to the third compartment and an innertop wall 70 which adjoins the internal wall 58 at one end and, atthe other end adjoins the top wall 59 at a point where the sloping portion 60 levels offto horizontal portion 71.

The second compartment 53 forms a lowermost chamber72 into which one arm 35 of the syphon tube 21 extends and an uppermost chamber 73 surmounting the lowermost chamber 72.

The lowermost chamber 72 is formed between the internal walls 58 and 25, the twovertical sidewalls common to the other compartments and a first part 74 of the innertop wall 70, which part 74 slopes in the same sense as the drip tray 60 and adjoins at one end the internal wall 58.

The uppermost chamber 73 is formed between the vertical sidewalls common to the other compartments, the internal sidewall 25 and a second part75 of the innertopwall 70, which part 75 adjoins the part 74 at one end and the outer top wall 59 atthe junction between parts 60 and 71.

The uppermost chamber 73 thus has a reduced cross-sectional area in comparison to the lowermost chamber 72 for reasons which have already been explained in the description accompanying Figure 4.

The third compartment is formed by the base 56, the internal wall 25, the two vertical outer side walls and the remaining outerwall 76.

The wall 76 has a lower vertical portion 77 adjoining the base 56, an uppervertical portion 78 disposed inwardly of the portion 77, and adjoining the outer top wall 59 at the junction between the parts 60 and 71 and an intermediate portion 79 adjoining the portions 77 and 78.

The portion 78 is co-planar with the internal wall 25 from which it is spaced to form an overflow opening 80.

Extending outwardly from the portion 77 ofthe wall 76 and sloping downwardly is a drain pipe 34.

Theotherarm 37 ofthesyphontube 21 has an end portion 38 located within the drain pipe 34. The bend in the syphon tube 21 is located level with the uppermost chamber 73 for the same reasons as previously explained in the description accompanying Figure 4.

The syphon tube 21 operates in the same manner as previously described commencing discharge when the level of the liquid in the uppermost chamber 73 has reached a predetermined uppermost level and terminating discharge when the liquid level in the lowermost chamber 72 has reached a predetermined lowermost level.

The portion 78 of the wall 76 is provided with an air vent 81 to ensure that the tank is vented to atmosphere to enable the siphoning action to be terminated when the liquid has fallen to a level co-terminous with the lowermost end 39 of the syphon arm 35.

Claims (9)

1. Apparatus for discharging condensate from a condensing type gas-fired applianceto a drainage point, the apparatus comprising a receptacle for receiving and collecting condensate discharged under gravity from the appliance and condensate discharge means adapted to commence discharge of the condensate from the receptacletothe drainage point only when the collected condensate has risen two a predetermined uppermost level and to continue discharge of the condensate thereafter only until the collected condensate has fallen to a predetermined lowermost level.

2. Apparatus as claimed in claim 1 in which the condensate discharge means comprises syphon means.

3. Apparatus as claimed in claim 2 in which the receptacle and drainage point are formed by a drain pipe which, in use, is arranged to slope downwardly from the appliance, the receptacle being formed by an uppermost portion of the drain pipe and the drainage point being formed by a lowermost portion of the drain pipe, and the arrangement being that, in use, condensate collected in the uppermost portion of the drain pipe can onlyflowtothe lowermost portion by way of syphon means.

4. Apparatus as claimed in claim 3 in which the arrangement is provided by a plate serving to block the pipe bore between the portions, communication between the portions being provided solely by the syphon means which extends through an aperture in the plate.

5. Apparatus as claimed in claim 4 in which the syphon means comprises a pipe in theform of an inverted U with an arm located in each portion of the drain pipe, there being an aperture in the wall of the uppermost portion of the drain pipeto provide an atmospheric vent.

6. Apparatus as claimed in claim 2 in which the receptacle comprises a tank and the drainage point comprises a drain pipe.

7. Apparatus as claimed in claim 6 in which the tank comprises a lowermost chamber surmounted byan uppermost chamber communicating therewith,the uppermost chamber having a smaller cross-sectional area than the lowermost chamber and the syphon means being arranged to commence discharge when the collected condensate has risen to a predetermined level within the uppermost chamber and continue discharge thereafter only until the condensate has fallen to a predetermined level within the lowermost chamber.

8. Apparatus substantially as hereinbefore described with reference to Figures 1 to3.

9. Apparatus substantially as hereinbefore described with reference to Figure 4 or Figure 5.