US 3771238 A
A laundry dryer is provided with a heated enclosure containing a heat exchanger. Water is pumped to a hot water heater through a conduit which is connected to the heat exchanger so that the water is pre-heated by the heat exchanger. The pump and a valve are connected in the conduit and are operated in response to a thermostatic control for the water heater which opens the valve and starts the pump when the water heater requires hot water. The pre-heating of the water in the heat exchanger cuts down on heating requirements of the water heater, thus economizing on power costs for the water heater.
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Description (OCR text may contain errors)
United States Patent Vaughn Nov. 13, 1973 LAUNDRY APPARATUS  Inventor: Donald E. Vaughn, 3105 Southside 'W 7 Camby Blvd., Jacksonville, Fla. 32216 Asslsmn' [hammer-James Yeung Att0rneyJohn H. Oltman et al.  Filed: Mar. 21, 1972 Appl. No.: 236,675
 ABSTRACT A laundry dryer is provided with a heated enclosure containing a heat exchanger. Water is pumped to 11 hot water heater through a conduit which is connected to the heat exchanger so that the water is pre-heated by the heat exchanger. The pump and a valve are connected in the conduit and are operated in response to a thermostatic control for the water heater which opens the valve and starts the pump when the water heater requires hot water. The pre-heating of the water in the heat exchanger cuts down on heating requirements of the water heater, thus economizing on power costs for the water heater.
4 Claims, 2 Drawing Figures -25 22 V 21 2a v 1 P v 1 31 I2 1 30 23 IL J -g5 PATENIEDImv 13 I973 HQL LAUNDRY APPARATUS BACKGROUND OF THE INVENTION U.S. Pat. No. 3,157,391 describes and claims a heat v reclaimer in which heat from a laundry dryer is partly vented through an exhaust and is partly recirculated back through the drier. The heat reclaimer includes an enclosure mounted above the dryer. The present invention provides a heat exchanger in such an enclosure for pre-heating water being supplied to a main water heater for a laundry system. Thus, the invention makes use of the heat of a laundry dryer to pre-heat water being supplied to a water heater, and thus cut down on heating requirements of the water heater and also fuel costs for the water heater.
SUMMARY OF THE INVENTION In a typical laundry installation of the invention, a water heater having a thermostatic control supplies water to a plurality of washers. A plurality of laundry dryers are provided with an enclosure heated by heat from the dryer, and heat exchanger means is mounted in each enclosure. A conduit is connected through the heat exchanger means in series to the hot water heater, and a pump and a valve are connected in the conduit. When the water heater requires hot water as sensed by the thermostatic control, this control opens the valve and turns on the pump so that the pump can supply water pre-heated by the heat exchanger means to the water heater. Since the water coming into the water heater is pre-heated, less heat is required in the water heater and therefore less fuel or power is required for the water heater.
Accordingly, it is an object of the present invention to save fuel costs in a laundry system such as might be used in a commercial laundry.
Another object of the invention is to pre-heat water being supplied to a hot water heater in a laundry system.
Another object of the invention is to utilize heat from laundry dryers in a laundry system to pre-heat water being supplied to a water heater.
A further object of the invention is to thermostatically control a pump and a valve in a conduit leading through heat exchanger means to a water heater so as to automatically supply water through the heat exchanger means to the heater when the heater requires hot water.
Other objects of this invention will appear from the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of laundry apparatus in accordance with a preferred embodiment of the invention; and
FIG. 2 is a fragmentary perspective view of a laundry dryer provided with a heated enclosure containing heat exchanger means for pre-heating water supplied to the water heater in the apparatus of FIG. 1.
Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
DETAILED DESCRIPTION The apparatus 10 of FIG. 1 includes a plurality of laundry dryers each designated 11. These dryers may be of the type which are commonly used in coin operated laundry systems. Each of these dryers is provided with a heated enclosure 12 at its top, and each of the heated enclosures 12 may be constructed in accordance with FIG. 2. It may be seen that there is a slot 13 communicating the interior of the dryer with the enclosure 12. There is also a vent stack 14 through which heat is vented from the dryer 11. The vent stack may connect with the dryer at the bottom in the manner shown in US. Pat. No. 3,157,391. Accordingly, the disclosure of said patent is incorporated herein by reference. The vent stack 14 communicates through conduit 15 with the enclosure 12. A blower forces air upwardly through the conduit 14, and a damper at the juncture of conduits 14 and 15 directs part of the heat back through the conduit 15 into the enclosure 12 and past a gas burner in the dryer 1 l. The heat may flow through the slot 13 back downward into the dryer 11.
Mounted in the enclosure 12 is a heat exchanger 16 which may consist of a few coils of a pipe 17. The heat exchanger 16 is preferably made of copper pipe since this material conducts heat well. A heat exchanger 16 is provided in each of the enclosures 12 for the dryers 11.
The apparatus 10 includes a hot water heater 18 which has a thermostatic control 19. Such hot water heaters with a thermostatic control are supplied commerically. There is a main water supply conduit 20 in which fresh cold water is available. A branch conduit 21 with a valve 22 leads from conduit 20 to the bottom of the water heater 18. When valve 22 is opened, cold water is supplied to the bottom of the water heater in the conventional manner. The conduit 17 connects from the main conduit 20 through all of the heat exchanger means 16 in series to the top of the water heater 18. A pump 23 is connected in the conduit 17, and a valve 24 is connected in the conduit 17 between the pump 23 and the first enclosure 12 of the series. The valve 24 and the pump 23 are electrically connected by wiring 25 to the thermostat control 19 of the water heater. The valve 24 and the pump 23 are thermostatically controlled, and such valves and pumps are available commercially.
In operation, when the hot water heater 18 requires hot water, the thermostatic control 19 automatically starts the pump 23 and opens the valve 24. The pump 23 is preferably a slow moving pump so that it pumps water at a slow rate through the conduit 17 and through all of the heat exchangers 16 to the top of the hot water heater 18. As the water passes through each of the heat exchangers 16 in the enclosures 12, heat in the enclosures 12 is transferred to the water through the heat exchangers 16. This heat raises the temperature of the water, and of course each heat exchanger in the series raises the temperature a little more than the preceding heat exchanger. Thus, by the time the water reaches the heater 18, it is considerably pre-heated.
Because of the pre-heating of the water, less heating is required in the water heater 18 in order to keep the water up to the desired temperature. This cuts down on power or fuel costs of the water heater. For example, where a gas water heater is used, less gas is needed to heat the water.
In most laundry installations, the apparatus 10 will also include a plurality of laundry washers, each of which is designated 26 in FIG. 1. A conduit 27 with a valve 28 leads from the heater 18 through branch pipes 29 to each of the washers 26. These conduits supply hot water to the washers 26 in response to automatic controls included in the washers. Another conduit 30 with a valve 31 leads from the main water supply conduit 20 through branch conduit 32 to each of the washers 26. These conduits supply cold water to the washers 26 in response to automatic controls included within the washers.
Thus, the invention provides for pre-heating of water being supplied to a water heater in a laundry system so as to cut down on the heat needed in the water heater to bring the water up to the required temperature and also to reduce the power requirements of the water heater. The power saving is substantial. The water is pre-heated in heat exchanger means provided in laundry dryers of the laundry system. Water is pumped through the heat exchangers in series so that each heat exchanger adds a little more heat to the water and thus gradually brings it up to the final temperature where it enters the water heater.
Having thus described my invention, I claim:
1. Laundry apparatus comprising,
a water heater,
a thermostatic control for said water heater,
a laundry dryer having an enclosure at the top thereof heated by heat from said dryer,
means for recirculating heat of said dryer through said enclosure and back into said dryer,
heat exchanger means mounted in said enclosure,
conduit means to supply fresh water to said water heater,
said conduit means including a conduit connected through said heat exchanger means to said water heater,
a pump connected in said conduit for pumping water through the same at'a relatively slow rate, and
a valve in said conduit between said pump and said water heater for controlling the flow of water in said conduit,
said pump and said valve having means to operate the same in response to said thermostatic control to open said valve and start said pump when said water heater requires hot water, so that said pump can supply water pre-heated by said heat exchanger means in said enclosure to said water heater.
2. The laundry apparatus as claimed in claim 1 in which said apparatus includes at least one additional clothes dryer having a heated enclosure with further heat exchanger means therein, and said conduit is connected through said first and second named heat exchanger means in series to said water heater.
3. In combination with a laundry dryer having a laundry drying chamber, a vent stack extending up from said drying chamber, an enclosure above said drying chamber, a bypass conduit extending from said vent stack to said enclosure for passing heated air to the latter, and means for passing heated air from said enclosure back down into said drying chamber, the improvement which comprises:
heat exchange water pipe means positioned in said enclosure to be heated by the hot air flowing therethrough from said bypass conduit to said drying chamber;
and means connecting said heat exchange water pipe means between a water supply and a hot water tank for preheating the water supplied to the latter.
4. A laundry system comprising a hot water tank for supplying hot water to washers;
water supply means for said tank;
a plurality of dryers, each having a laundry drying chamber, a vent stack extending up from said drying chamber, an enclosure above said drying chamber, a bypass conduit extending from said vent stack to said enclosure for passing heated air to the latter, and means for passing heated air from said enclosure back down into said drying chamber;
a plurality of heat exchange water pipes positioned respectively in said enclosures to be heated by the hot air flowing therethrough from the corresponding bypass conduit to the respective drying chamher;
and means connecting said heat exchange water pipes in series with each other between said water supply means and said hot water tank to preheat the water supplied to the latter.