DOWNFIRED HIGH EFFICIENCY GAS-FIRED WATER HEATER

CHAUFFE-EAU AU GAZ A HAUTE EFFICACITE A FLAMME VERS LE BAS

English Abstract

A high efficiency downfired gas water heater is provided which has a tank for storing water to be heated, a combustion chamber extending downwardly through a top end of the tank, and a gas burner operative to create hot combustion products within the combustion chamber. At the bottom end of the tank is a transfer chamber coupled to an external discharge conduit and to a single pass heat exchanger, in the form of multiple flue tubes, extending vertically through the tank and connected to the combustion chamber. In one embodiment of the water heater the burner is a power burner which forces the combustion products sequentially through the combustion chamber, heat exchanger, transfer chamber and discharge conduit. In another embodiment of the water heater a draft inducer fan is used to draw the combustion products through this path from the combustion chamber.

French Abstract

Chauffe-eau au gaz à haute efficacité à flamme vers le bas. Linvention comporte un réservoir permettant de stocker leau à chauffer, une chambre de combustion sallongeant vers le bas à travers une extrémité supérieure du réservoir et un brûleur à gaz fonctionnant pour créer des produits de combustion chauds dans la chambre de combustion. À lextrémité inférieure du réservoir se trouve une chambre de transfert raccordée à un conduit de décharge externe et à un échangeur de chaleur à un passage, prenant la forme de multiples tubes dévacuation, sallongeant à la verticale dans le réservoir et raccordés à la chambre de combustion. Selon un mode de réalisation du chauffe-eau, le brûleur est un brûleur soufflé qui force les produits de combustion, de façon séquentielle, à travers la chambre de combustion, léchangeur thermique, la chambre de transfert et le conduit de décharge. Selon un autre mode de réalisation du chauffe-eau, un ventilateur à tirage induit est utilisé pour attirer les produits de combustion, à travers ce tracé, à partir de la chambre de combustion.

Claims

CLAIMS:
1. Fuel-fired liquid heating apparatus comprising:
a tank adapted to hold a quantity of liquid to be heated, said tank having
upper and
lower ends;
a combustion products transfer chamber structure underlying said lower end of
said
tank;
a combustion product discharge conduit disposed externally of said tank and
having an
inlet end communicating directly with the interior of said combustion products
transfer chamber
structure;
a combustion chamber extending downwardly into the interior of said tank
through said
upper wall thereof, said combustion chamber being spaced upwardly apart from
said lower end
of said tank;
a single pass heat exchanger structure disposed in the interior of said tank
and being
defined by a plurality of flue pipes intercommunicating said combustion
chamber and said
combustion products transfer chamber structure, said flue pipes having inlets
and outlets
respectively connected directly to said combustion chamber and said combustion
products
transfer chamber structure; and
a fuel burner operative to create hot combustion products within said
combustion
chamber for transfer therefrom sequentially through said flue pipes, into said
combustion
products transfer chamber structure, and then outwardly from said combustion
products
chamber structure into said combustion products discharge conduit,
wherein said flue pipes spiral around a vertical axis extending through said
tank.
2. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said apparatus is a fuel-fired water heater.
3. The fuel-fired liquid heating apparatus of Claim 2 wherein:
said water heater is a gas-fired water heater.
4. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said single pass heat exchanger is a condensing heat exchanger structure.
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5. The fuel-fired liquid heating apparatus of Claim 4 further comprising:
a condensate drain fitting disposed on said combustion products discharge
conduit.
6. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said combustion chamber has a lower end, and
said inlets of said flue pipes are connected directly to said lower end of
said combustion
chamber.
7. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said combustion products transfer chamber structure has a top wall defined by
said
lower end of said tank.
8. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said fuel burner extends downwardly into the interior of said combustion
chamber.
9. The fuel-fired liquid heating apparatus of Claim 1 wherein:
said fuel burner is a powered fuel burner operative to sequentially force said
hot
combustion products downwardly through said combustion chamber, downwardly
through said
flue pipes into said combustion products transfer chamber structure, and then
outwardly from
said combustion products chamber structure into said combustion products
discharge conduit.
10. The fuel-fired liquid heating apparatus of Claim 1 further comprising:
an induced draft blower connected to said discharge conduits and operative to
sequentially draw said hot combustion products downwardly through said
combustion chamber,
downwardly through said flue pipes into said combustion products transfer
chamber structure,
and then outwardly from said combustion products transfer chamber structure
into and through
said combustion products discharge conduit.
11. The fuel-fired liquid heating apparatus of Claim 10 wherein:
said induced draft blower, during operation thereof, maintains a negative
pressure in
said combustion chamber and said combustion products transfer chamber
structure.

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Description

CA 02 82 3597 2 013-0 8-14
CA Application
Blakes Ref.: 75333/00057
DOWNFIRED HIGH EFFICIENCY GAS-FIRED WATER HEATER
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to fuel-fired water heaters
and, in
representatively illustrated embodiments thereof provides a specially designed
high efficiency
downfired gas water heater.
[0002] Fuel-fired storage type water heaters are commonly used in both
commercial and
residential applications to provide on-demand hot water to various types of
hot water-utilizing
plumbing fixtures such as sinks, showers, dishwashers and the like. In one
conventional
construction thereof, this type of water heater has a tank for holding
pressurized water to be
heated, a combustion chamber with a fuel burner therein for generating hot
combustion
products, and a flue extending through the tank interior. During firing of the
water heater, hot
combustion gases generated by the burner flow through the flue, with heat from
the combustion
gases being transferred from within the flue to stored tank water through
which the flue extends.
[0003] With increasing demands for both higher energy efficiency and lowered
water heater
production costs, it has become necessary to design fuel-fired water heaters
which are both
simpler in structure and capable of transferring a greater percentage of
burner-generated
combustion heat to the stored tank water. It is to these design goals that the
present invention
is primarily directed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a schematic horizontally directed cross-sectional view
through a downfired gas
water heater embodying principles of the present invention;
[0005] FIG. 2 is a cross-sectional view through a multi-tube flue portion of
the water heater;
[0006] FIG. 3 is a schematic horizontally directed cross-sectional view
through a first alternate
embodiment of the water heater and
[0007] FIG. 4 is a schematic horizontally directed cross-sectional view
through a second
alternate embodiment of the water heater.
DETAILED DESCRIPTION
[0008] Illustrated in FIGS. 1 and 2 is a downfired high efficiency gas-fired
water heater 10
having a vertically oriented metal tank 12 adapted to hold a quantity of
pressurized water 14 for
on-demand delivery to hot water-utilizing plumbing fixtures such as, for
example, sinks, tubs,
showers, dishwashers and the like. Tank 12 has a top end wall 16 with a cold
water inlet fitting
22427753.2 1

CA 02 82 35 97 2013-08-14
CA Application
Blakes Ref.: 75333/00057
18 and a hot water outlet fitting 20 thereon, and a bottom end wall 22 that
overlies a combustion
products transfer chamber 24 with which a discharge conduit 26 with a
condensate drain fitting
28 on its bottom end communicates.
[0009] A submerged tubular combustion chamber structure 30 having a bottom end
wail 32
and an open top end, extends downwardly through a central portion of the top
tank end wall 16.
The upper ends of a plurality of vertical, open-ended flue pipes 34
(representatively four in
number) are secured to the combustion chamber bottom end wall 32, with each of
the flue pipes
34 intercommunicating the interiors of the combustion chamber 30 and the
combustion products
transfer chamber 24.
[0010] Received in the upper end of the combustion chamber 30 is a powered
fuel burner 36
operative to receive fuel 38 and air 40 from sources thereof and responsively
create within the
combustion chamber 30 hot combustion products 42. During firing of the burner
36, the hot
combustion products 42 are sequentially forced downwardly through the flue
pipes 34 to
transfer combustion heat therethrough to the water 14, into the combustion
products transfer
chamber 24, and then outwardly into and upwardly through the discharge conduit
26.
Preferably, the pipes 34 define a condensing type heat exchanger, with the
resulting
condensate being drainable from the system via the fitting 28.
[0011] An alternate embodiment 10a of the previously described water heater 10
is shown in
FIG. 3, with components in the water heater 10a similar to those in the water
heater 10 having
been given the same reference numerals to facilitate comparison of the water
heaters 10 and
10a.
[0012] Water heater 10a is identical to the previously described water heater
10 with the
exception that in place of the straight flue pipes 34 utilized in water heater
10, the water heater
10a is provided with a plurality of flue pipes 44 (representatively two in
number) which are
connected to the bottom end 32 of the submerged combustion chamber 30 and
downwardly coil
around the central vertical axis 46. Pipes 44, like the pipes 34 in the water
heater 10,
intercommunicate the interiors of the combustion chamber 30 and combustion
products transfer
chamber 24. During firing of the burner 36 of the water heater 10a, the hot
combustion products
42 are sequentially forced downwardly through the pipes 42 into the chamber
24, and then
outwardly from the chamber 24 into the discharge conduit 26.
[0013] An alternate embodiment 10b of the previously described water heater
10a is shown in
FIG. 4, with components in the water heater 10b similar to those in the water
heater 10a having
been given the same reference numerals to facilitate comparison of the water
heaters 10b and
10a.
224277532 2

CA 02823597 2015-03-23
[0014] In the water heater 10b the hot combustion products 42 generated by the
fuel burner 48
are not sequentially forced by the burner 48 downwardly through the combustion
chamber 30,
downwardly through the flue pipes 44 into the combustion products transfer
chamber 24 and
then outwardly into the discharge conduit 26. Instead, an induced draft blower
50 installed in
the discharge conduit 26 sequentially draws the hot combustion products 42
downwardly
through the combustion chamber 30, downwardly through the flue pipes 44 into
the combustion
products transfer chamber 24. and then outwardly into and upwardly through the
discharge
conduit.
[0015] During operation thereof, the induced draft blower 50 maintains
negative pressures in
the combustion chamber 30 and in the combustion products transfer chamber 24,
thereby
providing the combustion system of the water heater 10b with a "draw-through"
mode of
operation. While this alternate mode of combustion system operation has been
representatively
illustrated in conjunction with the coiled flue pipes 44 (shown in FIGS. 3 and
4) is could also be
utilized in conjunction with the straight flue pipes 34 (shown in FIG. 1), if
desired, without
departing from principles of the present invention.
[0016] As can be seen from the foregoing, the single pass heat exchanger
structure in each of
the representatively illustrated downfired water heater embodiments 10-10b is
of a very simple
construction and provides for enhanced heat transfer from the burner-generated
hot combustion
products 42 to the tank water 14. In turn, this desirably reduces the
temperature of the
combustion products 42 entering the discharge conduit 26 and increases the
overall heating
efficiency of the associated water heater.
[0017] The foregoing detailed description is to be clearly understood as being
given by way of
illustration and example only.
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Representative Drawing