CA1197427A - Integrated domestic heating systems - Google Patents

Abstract

ABSTRACT

An integrated heating system comprising, in combination, a discharge stack, a water heater comprising a first heating exchanger discharging into said stack and a combustion chamber including a first fuel burner supplying hot combustion products to said heat exchanger, a space heater comprising a second heat exchanger and a second fuel burner supplying hot combustion products to said second heat exchanger, and a connection from said second heat exchanger to said first combustion chamber for enabling flow of gaseous products from said space heater through said first heat exchanger to said stack.

Description

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This invent.ion relates to the field of domestic heat-ing systems.
BACKGROUND OF THE INVENTION
Two of the principal energy consuming devices in the usual American name are the space heater for maintaining the home temperature and the water heater for maintaininy an ade~uate supply of hot water. These units are typically independent, each with its own heat exchanger and fossil fuel burner, and eac.h hav-ing its own connection to discharge combustion products to the stack or chimney of the house.
In modern days of increased fuel cost, it has been found desirable to reduce the temperature settings for home space heaters during periods when building occupan~s are absent or asleep. This can, of course, be done manually~ by resetting the thermostat each time a decrease or i~crease of temperature is desired, but automatic means for doing this has been devised in the form of a "setback" thermostat having a clock and means actuated by the clock for changing the temperature at which the thermostat maintains the system by a predetermined amount, for a predetermined period, beginning at a prede-termined time of day.
Additional contacts may be provided for performing related control functions.
As an added refinement, a setback thermostat may have first stage and second stage contact sets~ the former to control the flow of fuel at a first leve]. for normal use, and the second, set slightly lo~er~ to control the flow of additional fuel when outside temperature is low and the first stage operation does not provide enough heat to maintain the desired temperature.
BRIEF SUMM~RY OF TI-IE INVENTION
__ __ ___ The present invention interconnects a gas burning space hea-ter with a similar water heater so that the combustion products from the space heater are discharged through the heat '7 exchanger of the water heater, using induced draft. Thus~
whenever the temperature oL the space is too low and the space burner is opera-ting, waste heat from the space heater is being used to heat wa-ter, and operation of the water heater burner may be obviated except when the space heater is not in operation.
In accordance with the present invention, there is provided a logic control, adapted for use in a domestic heating system comprising a space heater having a gas valve and a thermostat, a water heater having a gas valve and a thermostat, and a draft induction component including a blower and a pressure switch, and wherein the combustion products of the space heater are conducted to the combus-tion chamber of the water heater, said logic control comprisin.g, in combination;
means for energizing said blower and enabling energization of sa.id gas valve of said space heater when the temperature in the space drops below a value determined by said thermostat of said space heater;
means for energizing said blower and enabling energization of said gas valve o:E said water heater when the temperature of said water drops below a value determined by said thermostat of said water heater;
means for inhibiting operation of either gas valve until said blower is in operation;
and means for disab]ing the second named means upon operation of the first named means.
Various advantages and features of novel-ty which characterize the invention are pointed out with par-ticularity in the claimsannexed hereto and forming a par-t hereof.

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However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described certain preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, in which like reference numerals indi.cate corresponding parts throughou-t the several views, Figure 1 is a schematic showing of one embodiment of the invention and Figure 2 gives details of a logic controlO

~ESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to Figure 1, an integrated heating system according to the invention is shown to comprise a space heater 10 having a gas burner 11, with an igniter or pilot light not shown, and a heat exchanger 12 for warming air entering at 13 and leaving at 14 to be conducted into a space containing a setback thermostat 15. A blower 16 induces draft through a flue 17 having an orifice 18 and containing a pressure sensor 19. The blower is driven by the shaft 20 of a plural speed electric motor 21, and dis-charges products of combustion of heater 10 through a conduit 22. Air is admitted to the combustion chamber 23 of heater 10 through an aperture 24.
The system also includes a wa-ter heater 30 having a gas burner 31, with an igniter or pilot ligh-t not shown, a heat exchanger 32 for heating water en-tering at 33 and :Leaving at 34, and a thermostat 35 for monitoring the ~emperature of the water.
Heater 30 discharges to a flue 37 connected to the stack or chimney 38 of the house, and the passage 40 for combustion products in heater 30 includes a restrictor 41 to improve heat transfer.
Flow of gas to burners 11 and 31 through conduits 42 and 43 having restrictions 44 and 45, all respectively, from an inlet conduit 50 is under the control of valving means 51, and motor 21 and valving means 51 are both controlled by a logic control 52, better shown in Figure 2, which is electrically energized from a utility power source 53. It receives inputs from thermostats 15 and 35 and pressure sensor 19 on cables 54, 55 and 56, and controls valving means 51 and motor 21 on cables 57 and 58, all respectively.
The general sequence of operation is as follows, starting from an initial condition wherein the space and the water are both at the desired temperatures, and no burner is in operation. If the water temperature drops, thermostat 35 acts through logic control 52 to first put blower 16 into operation at a predetermined speed and then liyht burner 31, which operate un-til the water reaches the desired temperature, and then are turned off.
If from the initial condition the space temperature drops, the thermostat 15 acts through logic control 52 to first put blower 16 into operation and then light burner 11, so that the hot combustion products are conducted through duc-t 22 into water heater 30 and pass throuyh heat exchanyer 32, where much of the heat is usefully extracted. Operation of thermostat 15 to select an appropriate speed for motor 21 and an appropriate 3Q fuel feed from valving means 51 will be described in connection with Figure 2, as will "setback" operation of thermostat 15.

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7~7 When the space reaches the desired temperature, hur.ner 11 and blower 16 are turned oE-EO
It is to be particularly noted that only one of burn rs 11 and 31 can be enexgized at any one time by valving means 51. If the space heater is in operation and ~he water temperature drops, burner 31 is not energized, and if the water heater is in operation and the space temperature drops, blower 16 remains turned on, burner 11 is turned on/ and burner 31 is turned off.
Attention is now directed to Figure 2, which gives details of logic control 52 and its interconnections with the rest of the system. Control 52 includes power terminals 61 and 62, blower terminals 63, 64, 65, and 65, gas valve solenoid terminals 70S 71, 72, 73, 74, and 75, setback thermostat terminals 85, 81, 82, 83, and 84, water thermosta-t terminals 90, 91, and 92, and pressure switch terminals 96 and 97.
Thermostat 15 is shown to comprise terminals 100, 101, 102, 103, and 104, a block 105~ a pair of Eirst stage contacts 106 and 107S a pair of second stage contacts 110 and 111, and a pair oE setback contacts 112 and 113.
Thermostat 35 is shown to comprise terminals 120~ 121, and 122, a pair of high temperature contacts 123 and 124, and a pair of low temperature contacts 125 and 126.
Pressure swi-tch 19 is shown to include terminals 130 and 131 and a pair oE switching contacts 132 and 133.
Valving means 51 is shown to include terminals 139, 14~, 141, 142, 143, and 144,metering solenoid valves 145, 146, and 147 and distributing solenoid valves 148 and 149. Valves 145-147 supply fuel from source 50 to a mani-Eold 150, from which valves 148 and 149 are supplied.
Motor 21 is shown to have a common terminal 153~ a ~ k~,-'7~'7 "hlgh'~ spaed terminal 154, a "low" speed terminal 155, and a further terminal 156.
Control 52 further includes a step down trans:Eormer 160 having a primary winding 161 and a secondary winding 162, a first stage relay 170, a second stage relay 180, and a water heater relay 190. Relay 170 has a winding 171, two pairs of normally open contacts 172 and 173, 174 and 175l and a pair of normally closed contacts 176 and 177. Relay 18U has a windiny 181, two pairs of normally open contacts 182 and .L83, and 184 and 185, and two pairs of normally closed contacts 186 and 187 and 138 and 189~ Relay 190 has a winding 191 and two pairs of normally open contacts 192 and 193, and 194 and 195.
Figure 2 shows a st,ate of the system, during normal daytime operation, when the temperatures of the space being heated and of the water are those desired. Motor 21 is not in operation, th.e gas valves are all closed, all thermostat contaets except eontaets 112 and 113 of thermostat 15 are open, and pressure switch contacts 132 and 133 are also open.
A circuit for energizing transformer 160 may be traced from terminal 61 through conductor 200, junction point 201, eonduetor 202, junction point 203, eonductor 204/ junction point 205, and eonduetor 206, the eircuit being completed through eonductor 207, junetion point 210, and conduetor 211 to terminal 62.
Clock 105 in thermostat 15 is energized from trans-former secondary winding through conductor 213, junction point 214, conductor 215, terminal 81l conductor 216 of cable 54, terminal 101, conductor 217, junction point ~20, and conductor 221, the circuit being completed through conduc-tor 222, terminal 100, conductor 223 of eable 54, -terminal 80, conductor 224, junetion point 225, and eonduetor 226.

If the space tampera-ture drops below a selected point say 70 degrees, thermostat contact~ 106l 107 close, completing a circuit from junction point 220 through conductor 229, junction point 230, contacts 10~ and 107, conductor 231, terminal 102, conductor 232 of cable 54, terminal 82, conductor 233, relay winding 171, conductor 234, junction point 235, and conductor 236, to junctlon point 225O Relay 170 is energized, disabl.ing at contacts 176 and 177 a water heater circuit presently to ~e described, and energizing ~an motor 21 at low speed through a circuit which may be traced from juncti.on point 203 through conductor 240, relay contac-ts 173 and 172, conductor 241~ relay contacts 186 and 187 now closed, conductor 242, terminal 65, and conductor 243 o~ cable 58 to low speed motor terminal 155, the circuit being completed from terminal 153 through conductor 244 of ca~le 58, terminal 63, and conductor

2~5 to junction point 210.
Operation of the fan induces air flow at ~ low speed which closes pressure switch contacts 132 and 133, and relay 170 has closed contacts 174 and 175, so tha-t a circuit ma~ now be traced from junction point 214 through conductor 250, junction point 251, conduc-tor 252, terminal 96, conductor 253 of cable 56l terminal 130, pressure sensor contacts 132 and 133, terminal 131, conductor 254 of cable 56, terminal 97, conductor 255, junction point 256, conductor 257, relay contacts 174 and 175 now closad, conductor 258, junction point 259, conductor 260, terminal 73, conductor 261 of cable 57, terminal 142 and conductor 262 to gas solenoid 148, the circuit being completed through conductor 263, junction point 264, conductor 265, junction point 266, conductor 267, junction point 268, conductor 269, terminal 139, conductor 270 of cable 57, terminal 70/
conductor 271, junction point 272l and conductor 273 (junction 7 ~ 2 7 point 274, conductor 275~, to junction point 235. I'hus burner 11 and blower 16 are both in operation at predetermined ]o~
rates.
From junction point 259 the circuit is also continued by conductor 280, junction point 281, conductor 282, relay contacts 188 and 189 now closed, conductor 283, texmi.nal 72~
canductor 284 of cable 57, terminal 141, and conductor 285 to low rate solenoid 146, the circuit being completed to junction point 266 through conductor 286.
Valve 146 passes fuel at a normal rate, and valve 148 distributes the fuel to the space hea-ter.
Note that valves 145, 146, and 148 cannot be opened unless motor 21 is in operation to cause closure of pressure switch contacts 132, 133.
If the amount of fuel supplied through valve 146 is not sufficient, and the space temperature drops sligh-tly further, say to 68 degrees, second stage contacts 110 and 111 of thermostat 15 close, completiny a circuit from junction point 220 through conductor 287, junction point 288, contacts 110 and 111, conductor 289, terminal 103/ conductor 290 of cable 54, terminal 83, and conductor 291 to relay winding 1$1, the circuit being completed through conductor 292 to junction point 272.
Relay 180 pulls in, opening~ at contacts 186, 187, the circuit for low speed operation of motor 21, and at contacts 188 and 189, the circuit for valve 146, ~hich accordingly closes, and closing, at contacts 183, 182, a first circuit for high speed operation of motor 21, and at contacts 184, 185 a second circuit for high rate valve 145. The first circuit may be traced from junction point 201 through conductor 293, contacts 183 ".82, conductor 294, terminal 64, and conductor 295 of cable 58 to high speed motor terminal 154, and is completed from terminal 153 as before. The second circuit may be traced from junction point 281 through conducto~ 296, relay contacts 184 and 185, conductor 297, terminal 71, conduc~or 298 of cable 57, terminal 140, and conductor 299 to valve 145/ and beiny completed through conductor 300 to junction point 268. Now burner 11 and blower 16 are both ln operation at high rates.
When operation of the system raises the space temperature abo~e 68 degrees, the settiny of thermostat contacts 110 and 111, relay 181 opens and the operation reverts to that controlled by thermostat contacts 106 and 107. Eirst stage contacts 106 and 107 have remalned closed to energize relay 170. If the low level heating is not enough to maintain the temperature at 68 degrees, high level hea~ing is again called for. If low level operation is now enough to maintain temperature, such operation continues/ and if the space temperature rises to 70 degrees, contacts 106 and 107 deenergize relay 171, and all heater operation is interrupted.
Operation of the space heater for satback operation is the same as was described above, except that contacts 106~
107, and 110, 111 are arranged to close at lower temperatures.
During setback operation eontacts 112 and 113 are op~n, as will be deseribed below.
If, from the initial conditions previously defined, the water temperature drops~ contacts 123 and 124 of thermostat 35 operate to turn on burner 31, as will now be described~ As a mat-ter of practice, when the conditions are such that setbaek of thermostat 15 is appropriate~ the conditions are also such -that there is little likelihood of need for hot wa-ter, and the temperature at which thermostat 35 turns on burner 31 may be lowered during such periods. This is ef~ectively accomplished ,~

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by the provision in thermostat 15 of further contacts 112 and 113 which are normally closed, but which open when -thermostat 15 is setback, and hy providing in thermostat 35 a second pair of contacts 125 and 126 closing at a lower water temperature than contacts 123 and 124. Consider first the normal condition of the system.
As the water temperature falls, contacts 123 and 124 close, completing a circuit which may be traced Erom junction point 288 in thermostat 15 through conductor 310, contacts 112 and 113, conductor 311, terminal 104, conductor 312 of cable 54, terminal 84, conductor 313, t~rminal 90, conductor 314 of cable 55, terminal 120, thermostat contacts 123 and 124, junetion point 316, conduc-tor 317, terminal 121, conductor 320 of cable 55, terminal 91, conductor 321, relay contacts 177 and 176 now closed, conductor 322, junction point 323, and conductor 324 to relay winding 191, the circuit being completed through conductor 325 to junction point 272. Note that relay 190 can be energized only if relay 170 is deenergized so that contacts 176, 177 are closed.
Relay 190 pulls in, closing at contacts 193, 192 a first circuit, for opera~ing motor 21 at a speed appropriate for exhausting water heater combustion products, and at contacts 195, 194 a second circuit for solenoid valve 147.
The first circuit may be traced from junction point 205 through conductox 330~ contacts 193 and 192, conductor 331, terminal 66 and conductor 332 of cable 53 to terminal 156. the circuit is completed as previously described. Operation of blower 16 by motor 21 c:Loses pressure switch contacts 132 and 133, but relay contacts 175 and 174 are now op2n and no operation of valves 145, 146, and 148 results.
The second circut may be traced from junction point 1~) 256 through conductor 333, relay contacts 195 and 194, conductor 334, terminal 74, conductor 335 of cable 57, terminal 143, conductor 336, valve 147, conductor 337, junction point 343, and conductor 341 to junction point 264.
The circuit i5 extended from junction point 323 through conductor 342, terminal 75, conductor 343 of cable 57, terminal 144 and conductor 344 to solenoid valve 149, the circuit being completed through conductor 345 to junc-tion point 34Q.
Thus valves 147 and 149 are open to supply gas to burner 31 of water heater 30. Note that valve 147 cannot be opened unless motor 21 is in operation to close pressure switch contacts 132 r 133. When the water reaches a desired temperature, contacks 123 and 124 are open, deenergizing the valve~
Now consider the operation of the water heater in the setback condition of the system. Contacts 112 and 113 in thermostat 15 are open, disabling water thermostat contacts 123 and 124. The water temperature can continue to fall until it reaches the lower value at which thermostat contacts 125 and 126 engage. This completes a circuit from junction point 251 through conductor 350, terminal 92, conductor 351 of cable 55, terminal 122, and thermostat contacts 125 and 126, to junction point 316, from which the circui-t to relay winding 191 has already been traced. Thus during set~ack operation the blower and valves 147 and 149 are ackuated as before, but to maintain a lower water temperature. At the end of the setback period, thermostat contacts 112 and 113 again closel restoring water heater control through relay 191 to thermostat contacts 123 and 124.
If the water heater is in operation and the space tempera-ture drops, thermostat contacts 106 and 107 close as .''-~"'' ~

before to energize relay 1700 Relay contacts 176 and 177 open, interrupting the circuit to relay 191 to disable valves 147 and 149 and to interrupt motor energization on conductor 332.
Blower operation i5 maintained, however, by contacts of relay 170 (or 180) so that pressure switch contacts 132, 133 rema.-in closed and operation of valves 145, 146, and 148 is continued.
If the space heater is in operation and the water temperature drops, no change in system operation occurs because relay 190 is deenergized at relay contacts 176, 177.
Referring again to Figure 1, it will be evident that blower 16, orifice 18, and pressure sensor 19 may, if preferred, be located at the outlet from water heater 30, as indicated in broken lines at 360 in the Figure.
From the above it will be evident that the invention comprises a system including a space h.eater and a water heater in which the waste heat from the former is used in the latter.
The system includes means for preventing fuel from being supplied to the water heater when the space heater is in operation, allows for setback operation of both heaters, and 2a prevents the supply of fuel to either burner un].ess an induced draft of adequate size is proviaed~
Numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features -thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts, within -the pr:inciple of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A logic control, adapted for use in a domestic heating system comprising a space heater having a gas valve and a thermostat, a water heater having a gas valve and a thermostat, and a draft induction component including a blower and a pressure switch, and wherein the combustion products of the space heater are conducted to the combustion chamber of the water heater, said logic control comprising, in combination;
means for energizing said blower and enabling energization of said gas valve of said space heater when the temperature in the space drops below a value determined by said thermostat of said space heater;
means for energizing said blower and enabling energization of said gas valve of said water heater when the temperature of said water drops below a value determined by said thermostat of said water heater;
means for inhibiting operation of either gas valve until said blower is in operation;
and means for disabling the second named means upon operation of the first named means.

2. Apparatus according to claim 1 in which the first named means comprises a first relay energized by said thermostat of said space heater and having normally open contacts which close to energize said gas valve of said space heater, the second named means comprises a second relay energized by said thermostat of said water heater and having normally open contacts which close to energize the gas valve of said water heater, and the last named means includes a set of normally closed contacts of said first relay which open to disable said second relay.

3. Apparatus according to claim 1. in which the third named means comprises a pressure sensor including normally open contact means for disabling said valves, and means responsive to operation of said blower for closing said normally open contact means.