US20100107993A1

US20100107993A1 - Energy efficient induced air gas water heater

Info

Publication number: US20100107993A1
Application number: US12/261,242
Authority: US
Inventors: Jeff Lyons
Original assignee: American Water Heater Co
Current assignee: American Water Heater Co
Priority date: 2008-10-30
Filing date: 2008-10-30
Publication date: 2010-05-06
Also published as: CA2683388A1; CN101726092A

Abstract

An energy efficient induced air gas water heater includes a water tank; a flue associated with the water tank; a burner that combusts a mixture that creates combustion products that pass through the flue; a blower that receives the combustion products from an outlet of the flue; a damper that movably covers and uncovers the flue outlet or an outlet of the blower, the damper being in an open position when the burner and/or the blower are operating and being in a closed position when the burner or the blower are not operating.

Description

TECHNICAL FIELD

This disclosure relates to energy efficient induced air gas water heaters. More particularly, the disclosure relates to an energy efficient damper installed on the outlet of a blower or at the top of a flue.

BACKGROUND

In water heaters that include blowers, such as induced air gas water heaters, residual heat and gases escape through the outlet of the blower when the water heater is in standby mode. Exhausting combustion gases is necessary when the burner and the blower are operating. However, when the blower is not operating and the water heater is in standby mode, the release of residual heat from the water heater is inefficient as hot air from the water heater storage tank is lost.
Thus, a device that allows the release of combustion gases during operation, but preventing the loss of residual heat during standby mode could be helpful.

SUMMARY

I provide an energy efficient induced air gas water heater that includes a water tank; a flue associated with the water tank; a burner that combusts fuel that creates combustion products that pass through the flue; a blower that receives the combustion products from an outlet of the flue; a damper that movably covers and uncovers the flue outlet or an outlet of the blower. The damper may be in an open position when the burner and/or the blower are operating uncovered and may be in a closed position when the burner and/or the blower are not operating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view, taken in section, illustrating details of an exemplary water heater.

FIG. 2 is a schematic front view, taken in section, illustrating details of another exemplary water heater.

FIG. 3 is a top plan view of an exemplary damper that may be utilized with water heaters of the type shown in FIGS. 1 and 2.

FIG. 4 is a side view of the damper shown in FIG. 3 with the movable disc shown oriented in multiple positions.

FIG. 5 is a schematic top plan view of another exemplary damper.

FIG. 6 is a schematic side view of the damper of FIG. 5 in a closed position.

FIG. 7 is a schematic side view of the damper shown in FIG. 5 in an open position.

FIG. 8 is a schematic top plan view of yet another exemplary damper.

DETAILED DESCRIPTION

It will be appreciated that the following description is intended to refer to specific examples of structure selected for illustration in the drawings and is not intended to define or limit the disclosure, other than in the appended claims.
This disclosure relates to a water heater, such as an induced air gas water heater, to allow for the release of combustion gases from a flue when a blower and burner are running and to prevent the loss of residual heat from a heated water tank when the blower and burner are not operating, i.e., in standby mode.
With reference to FIGS. 1 and 2, exemplary water heaters 100 are illustrated. Water heater 100 includes jacket 104 which surrounds a water tank 106, a main burner 114 in a combustion chamber 115. Passing through the center of the tank 106 is a substantially vertically oriented flue 110, which may incorporate a series of baffles (not shown) to better transfer heat generated by the main burner 114 to water in water tank 106. Water tank 106 is preferably of mains pressure capability and capable of holding heated water. Water tank 106 is preferably insulated by foam insulation 108. Alternative insulation may include fiberglass or other types of fibrous insulation and the like. Fiberglass insulation 109 surrounds combustion chamber 115 and the lowermost portion of water tank 106. It is possible that heat resistant foam insulation can be used if desired. A foam dam 107 or other means separates foam insulation 108 and fiberglass insulation 109.
Located underneath the water tank 106 is the main burner 114 which uses natural gas or other gases, such as LPG, for example. Other suitable fuels may be substituted. Main burner 114 combusts a gas and air mixture and the hot products of combustion resulting rise up through flue 110, possibly with heated air.
The products of combustion pass upwardly and out the top of jacket 104 via flue outlet 116 after heat has been transferred from the products of combustion. The flue outlet 116 discharges into a blower/air inducer 120. Blower 120 includes a fan 122 that induces combustion products upwardly through flue 110 and into the housing of blower 120. Those hot combustion products are mixed with ambient air that is introduced into blower 120 through inlet 135. Mixture of those two components reduces the temperature of the combustion products and allows that mixture to be discharged from outlet 125 at a temperature that is low enough to be compatible with materials that are not resistant to very high temperatures such as PVC pipe, as one example. This allows for the increased flexibility of installing water heater 100.
With reference to FIGS. 1 and 2, an exemplary damper 200 is illustrated. The damper 200 is sized and shaped to securely cover the blower outlet 125 as shown in FIG. 1. Alternatively, the damper 200 is sized and shaped to securely cover the flue outlet 116 as shown in FIG. 2.
The damper 200 has an open position and a closed position. In an open position, combustion products, such as gases and heat, exit from the water heater 100 via the flue 110. The damper 200 is in the open position when the burner 114 and the blower 120 are operating and combustion products are being produced to heat water in the storage tank 106. In a closed position, heat is prevented from leaving the water heater 100 as the damper 200 closes either the blower outlet 125 (FIG. 1) or the flue outlet 116 (FIG. 2). The damper 200 is in the closed position when the burner 114 and the blower 120 are not operating and loss of the heat from the storage tank 106 is undesirable.
FIGS. 3 and 4 show a representative or exemplary damper 300 which may be used as one construction of a damper 200 as shown in FIGS. 1 and 2. The damper 300 includes a frame 310, a substantially flat and round disc or plate 320, and a pivot member or pin 330. Frame 310 is attached to the outlet 125 of blower 120 or the outlet 16 of flue 110. This connection may be made by any means depending on the material of the frame 310. For example, if 310 is a metal such as the same type of metal as flue 110, frame 310 may be spot welded or fixed to the outlet 116 by any other known methods of fixing materials together.
The frame 310 can be located entirely within outlet 116 or can also be connected to outlet 116 at bevelled side portions 340 that can be sized and shaped to match complementary sizes and shapes of outlet 116 to facilitate an easy connection between the two devices.
Moveable disc 320 connects to pivot member 330 and is moveable between a closed, substantially horizontal position and a substantially vertical open position as shown by the range of motion indicated by arrow A in FIG. 4. It is preferred to size disc 320 to have an outer diameter that is slightly smaller than the inner diameter of frame 310 as shown by the gap indicated at arrow B in FIG. 4. This allows for expansion and contraction of the various structures such as frame 310 and disc 320 depending on the heating and cooling conditions and allows for complete freedom of movement along the range indicated by arrow A of FIG. 4. Moveable disc 320 should also be manufactured from a heat resistant material such as metal. While frame 310 and disc 320 are depicted as round, other shapes may be used as appropriate.
With reference to FIGS. 5-7, another exemplary damper 400 is illustrated. Damper 400 is sized and shaped to securely cover the blower outlet 125 or the flue outlet 116. Similar to the exemplary damper 300, damper 400 has an open position in which combustion products exit the water heater 100 and a closed position when the water heater is in standby mode.
The damper 400 includes a frame 410, multiple flaps 420 and a support frame 430. Damper 400 has a substantially circular frame 410 that is fixed to the substantially circular outlet 116 or 125. Four flaps 320 connect to the frame 410 and are made from a flexible, but heat resistant material such as santoprene, for example. The flexible flaps 420 are maintained in a closed position by support frame 430 which is essentially comprises support members that form a “cross” or “X” and connect interiorly of frame 410. The support frame 430 allows the four flaps to lie in a closed position when the water heater is in standby mode. This is particularly well shown in FIG. 6.
FIG. 7 shows flaps 420 having been displaced into a more vertical position by the induction of air and the passage of combustion products from outlet 125 or outlet 116. Support frame 430 remains in a constant position whether the water heater is operating or in standby mode.
FIG. 8 shows a top plan view of another damper 500 which is similar to damper 400 of FIG. 5. However, instead of four flaps 420, damper 500 has six flaps 520 and a corresponding support frame 530 that accommodates the two additional flaps. Damper 500 operates substantially in the same manner as damper 400. Alternate numbers of flaps may be utilized as desired.
Water heater 100 may be in an operating condition or in a standby mode. When the temperature of water in water tank 106 falls below a preselected temperature level, a controller 130 activates blower 120 to induce the flow of air through 110 by way of combustion chamber 115 which typically has an access opening to draw ambient air into combustion chamber 115. Then, upon receiving a signal that air is successfully moving through water heater 100, controller 130 activates burner 114. Burner 114 produces combustion products that pass upwardly through flue 110 and outwardly of flue 110 to outlet 116. Those combustion gases mix with ambient inlet air passing through inlet opening 135 which then combine with the combustion products and exit through blower outlet 125.
When the temperature of water within tank 106 again reaches approximately the preselected temperature, the controller terminates operation of burner 114 and typically shortly thereafter terminates operation of blower 120.
During standby mode when burner 114 is not operating, there is no induction of combustion products and air through flue 110. However, due to the “open” nature of water heater 100 wherein ambient air may enter combustion 115 and there would ordinarily be an opening at the top 104 of water heater 100, such ambient air would tend to enter combustion chamber 115, pass through flue 110 and exit outwardly at outlet 116 and outlet 125. This creates a passage of cooling air that reduces the efficiency of the water heater by as much as 7 percent. This is undesirable.
As shown in FIG. 1, placing a damper such as damper 200 at outlet 125 prevents this natural flow of ambient air into water heater 100 that would otherwise pass cooling air through flue 110 and reduce energy efficiency. The presence of damper 200 substantially prevents this free-flow of cooling air, retains the heat within tank 110, thereby increasing energy efficiency by as much as 7 percent as shown in the Example and Comparative Example below.
Tank Capacity, Measured/Rated: 47.8/50.00

EXAMPLE


Summary	Measured	Minimum Gama Listing

Recovery Efficiency	0.89
Energy Factor	0.700	0.58
First Hour Supply	0.00

Simulated Use Test


Correction Factor/Heating Value (Gas only)	0.9489/1,044.68
Total gallons drawn during test	64.43
Gallons drawn during first cycle	10.73
Outlet minus inlet water temperature for first cycle,	83.68
Fahrenheit
Average of outlet minus inlet water temperature	82.70
during all draws, Fahrenheit
Total energy used during 24 hour simulated use	62,274.73
test, Btu
Energy consumed during recovery test (first cycle),	8,702.36
Btu
Energy consumed after draw/recovery period, Btu	3,443.40

	Initial	First Cycle	After recovery	Final

Mean tank	136.08	136.84	136.61	129.50
temperatures,
Fahrenheit

Time from last draw/recovery Tmax to 24 hours,	18.50
hours
Total standby time, hours	23.69
Average ambient temperature during all standby,	68.40
Fahrenheit
Average mean tank temperature during all standby,	132.00
Fahrenheit
Average ambient temperature from last draw/	68.33
recovery Tmax to 24 hours, Fahrenheit
Average mean tank temperature from last draw/	133.23
recovery Tmax to 24 hours, Fahrenheit

First Hour Draw Test


	Average outlet temperature, Fahrenheit	0
	Average inlet temperature, Fahrenheit	0
	Water drawn during test, gallons	0
	Total elapsed time of test, minutes	0

Calculated Values


	Hourly standby losses, Btu/hour	334.12
	Standby heat loss coefficient, Btu/hour-Fahrenheit	5.15
	Daily water heating energy consumption, Btu/day	62,182.75
	Adjusted daily water heating energy consumption,	62,657.71
	Btu/day
	QHW - Energy used to heat water, Btu/day	49,837.82
	QHW77 - Energy used to heat water over 77	46,293.85
	degrees Fahrenheit rise, Btu/day
	Modified daily water heating energy consumption,	59,113.73
	Btu/day

	Delivery:	Inlet:

Average temperatures, Fahrenheit	140.63	57.93

Tank Capacity, Measured/Rated: 47.8/50.00

COMPARATIVE EXAMPLE


Summary	Measured	Minimum Gama Listing

Recovery Efficiency	0.87
Energy Factor	0.657	0.58
First Hour Supply	0.00

Simulated Use Test


Correction Factor/Heating Value (Gas only)	0.9415/1,043.68
Total gallons drawn during test	64.54
Gallons drawn during first cycle	10.75
Outlet minus inlet water temperature for first cycle,	82.48
Fahrenheit
Average of outlet minus inlet water temperature	85.90
during all draws, Fahrenheit
Total energy used during 24 hour simulated use	72,946.09
test, Btu
Energy consumed during recovery test (first cycle),	9,809.46
Btu
Energy consumed after draw/recovery period, Btu	8,112.64

	Initial	First Cycle	After recovery	Final

Mean tank	137.86	140.70	142.17	139.95
temperatures,
Fahrenheit

Time from last draw/recovery Tmax to 24 hours,	18.50
hours
Total standby time, hours	23.64
Average ambient temperature during all standby,	68.54
Fahrenheit
Average mean tank temperature during all standby,	137.01
Fahrenheit
Average ambient temperature from last draw/	68.40
recovery Tmax to 24 hours, Fahrenheit
Average mean tank temperature from last draw/	139.46
recovery Tmax to 24 hours, Fahrenheit

First Hour Draw Test

Calculated Values


	Hourly standby losses, Btu/hour	471.72
	Standby heat loss coefficient, Btu/hour-Fahrenheit	6.64
	Daily water heating energy consumption, Btu/day	68,666.85
	Adjusted daily water heating energy consumption,	68,514.03
	Btu/day
	QHW - Energy used to heat water, Btu/day	53,271.01
	QHW77 - Energy used to heat water over 77	47,649.68
	degrees Fahrenheit rise, Btu/day
	Modified daily water heating energy consumption,	62,892.70
	Btu/day

	Delivery:	Inlet:

Average temperatures, Fahrenheit	144.43	58.53

On the other hand, when burner 114 is operating and combustion products are generated, such combustion products must be efficiently removed from the system. Therefore, the damper 200 provides a simple and efficient manner of allowing those combustion products to be removed, but still maintain the closed system when burner 114 is not operating.
Although specific structures and steps have been shown and described herein for purposes of illustration and exemplification, it is understood by those of ordinary skill in the art that the specific structures and steps shown and described may be substituted for a wide variety of alternative and/or equivalent implementations without departing from the scope of the appended claims. This disclosure is intended to cover any adaptations or variations of the structures and steps discussed herein.

Claims

1. An energy efficient induced air gas water heater, the water heater comprising:

a water tank;

a flue associated with the water tank;

a burner that generates combustion products that pass through the flue;

a blower having a blower outlet that receives the combustion products from an outlet of the flue;

a damper that movably covers and uncovers the flue outlet or the blower outlet, the damper being in a substantially open position when the blower and/or burner are operating and being in a substantially closed position when the blower and/or burner are not operating.

2. The water heater of claim 1, wherein the damper comprises:

a frame sized and shaped to securely attach to the blower outlet or the flue outlet;

a movable cover secured within the frame to cover the blower outlet or the flue outlet;

a pivot member that connects the movable cover to the frame and that allows for the movable disc to move;

the damper being in an open position when the blower and the burner are operating such that the combustion products exit the water heater, the movable cover moved by airflow and/or flow of the combustion products to uncover the blower outlet or the flue outlet; and

the damper being in a closed position when the blower and the burner are not operating to retain heat within the flue and the water tank, the movable cover covering the blower outlet or the flue outlet.

3. The water heater of claim 1, wherein the movable cover moves to a position to cover the blower outlet or the flue outlet through gravity.

4. The water heater of claim 1, wherein the frame and the movable disc are metal.

5. The water heater of claim 1, wherein the damper is comprised of a heat resistant material.

6. The water heater of claim 1, wherein the flue is substantially vertically oriented and passes substantially through the center of the water tank and the blower is positioned above and surrounds the outlet of the flue.

7. The water heater of claim 1, wherein the damper comprises:

a frame sized and shaped to securely attach to the blower outlet or the final outlet;

a plurality of flaps that are collectively sized and shaped to cover the blower outlet or the flue outlet, each flap attached at an edge portion to the frame;

the damper being in an open position when the blower and the burner are operating such that the combustion products exit the water heater, the plurality of flaps moved upward by airflow and/or flow of the combustion products to uncover the blower outlet or the flue outlet; and

the damper being in a closed position when the blower and the burner are not operating to retain heat within the flue and water tank, the plurality of flaps covering the blower outlet or the flue outlet.

8. The damper of claim 7, wherein the plurality of flaps move to a position to cover the blower outlet or the flue outlet through gravity.

9. The damper of claim 7, wherein the plurality of flaps are comprised of an elastic material.

10. The damper of claim 7, wherein the damper is comprised of a heat resistant material.