GB2056650A

GB2056650A - Gas-fired heater

Info

Publication number: GB2056650A
Application number: GB7928549A
Authority: GB
Original assignee: United Gas Industries Ltd
Current assignee: United Gas Industries Ltd
Priority date: 1979-08-16
Filing date: 1979-08-16
Publication date: 1981-03-18
Also published as: GB2056650B

Abstract

A gas-fired heater has a fan 20 which drives air in paths through the heater into a space to be heated. There are three paths, a first path A flowing between combustion chamber 12 and a heat exchanger 13, a second path B flowing between the heat exchanger and a divider plate 21 and a third, cool air path C, flows up between the divider plate and a back wall of the heater across the top, down over the front wall and emerges with the other flows through low-level grill 23. This path maintains the casing of the heater at a comfortable temperature in spite of the high interior temperature of the heater. <IMAGE>

Description

SPECIFICATION Gas-fired heater This invention relates to gas-fired heaters of the kind where a fan assists the flow of convection air to be heated through the heater. Such'heaters will be termed hereinafter "heaters of the kind described".

The invention provides a heater of the kind described wherein the fan draws in convection air at or near the base of the heater and directs it into one or more paths leading up through the heater and then down to emerge at or near the base of the heater.

Preferably said heater includes a combustion chamber, one or more of the said paths comprising a hot air path leading convection air over said combustion chamber to be heated thereby and another of said paths comprising a cool air path lying adjacent exterior walls of the heater and not contacting said combustion chamber.

The heater may have a heat exchanger spaced from but connected to the combustion chamber to receive combustion products therefrom, and another of said paths comprising a second hot air path may lead convection air into contact with said heat exchanger, said cool air path not contacting said heat exchanger.

The cool air path may be defined by a divider plate separating it from the other paths and may extend effectively around the exterior rear, top and front walls of the heater. A vent from the cool air path may direct air therefrom into a control compartment.

A specific embodiment of the invention is shown in the accompanying drawing, which is a diagrammatic side section through a gas convector heater.

The heater has a burner 11 in a combustion chamber 12, the exhaust products being directed down into a double pass heat exchanger 13 through a connection 14 before leaving the heater through flue 15. Combustion air is drawn in through duct 16 buy a fan 17. The flue 15 and duct 16 may terminate in a balanced flue arrangement (not shown).

The heater heats room air which is drawn in through low-level vents 18 by a tangential fan 20.

The incoming air is divided into three paths. A first path shown by arrows A flows between the combustion chamber 12 and the heat exchanger 13, and since these parts are the hottest, air flowing in this path reaches the highest temperature. A second path shown by arrows B flows between the heat exchanger 13 and a divider plate 21. Air following this path becomes hot but not as hot as that in the first path.

The third path shown by arrows C flows between the divider plate 21 and the rear of the heater. The divider plate extends across the top of the heater to a point adjacent the front of the heater, at which point the three flows are not longer separated and begin to mix. The third flow has not contacted the heat exchanger or the combustion chamber and is therefore coolerthan the other two flows.

From the top of the heater the three flows are then directed downwardly adjacent the front of the heater and finally emerge from a low-level grill 23.

Although mixing of the flows begins at the beginning of this final downward pass, the cool air of the third flow tends to remain in contact with the outer wall. It will be seen from the figure that in effect the heater is encased in the cool air of the third flow and this maintains the outer casing of the heater at a lower temperature than would otherwise be the case. It is found that the casing never reaches an uncomfortably hot temperature in practice in spite of the high interior temperature of the heater. Moreover, because the heated air emerges at the lower level, the room is more evenly heated, the tendency to a layer of cold air being formed at ground level being avoided.

To increase further the comfort level in use, the heat is fitted with a thermostatic switch (not shown) which prevents the fan 20 from operating until a temperature sensor at the top of the heat exchanger indicates that hot air is available. This avoids an initial blowing of cold air into the room while the heater warms up.

The cool third air flow is also used to cool the control circuits of the heater (not shown) which control the automatic starting and stopping of the heater under the influence of an integral thermostat and also of a timing clock. The electronic controls are mounted at one side of the heater and vents 24 direct a part of the cool air into a compartment housing the controls.

A further refinement is a series of vertical guides 25 adjacent the grill 23. These can be adjusted by rotating about their horizontal axes so as to direct the emerging hot air to a selected preferred area of the room. The guides may be adjusted once and for all when the heat is installed or an external slide controi may allow the user to altertham at will.

Yet another refinement is the inclusion of a humidifier (not shown). This comprises a wick kept wetted by a water reservoir (not shown), the wick extending into the hot air stream.

The integral thermostat has a main phial 26 which senses the temperature of the incoming cool air stream and operates to turn the heater off when a predetermined temperature is reached. This arrangement by itself tends to overshoot the predetermined temperature since hot air continues to be blown into the room until the thermostat operates. A secondary phial 26' is therefore positioned in the hot air stream to provide a degree of anticipation of the effect of the hot air on the room temperature. The phial 26' when it senses hot air advances the operation of the main phial 26 to turn the heater off.

Similarly, when the heater cools down after being turned off, phial 26' anticipates the operation of the main phial to turn the heater on.

1. A heater of the kind described, wherein the fan is located to drawn in a stream of air at or near the base of the heater and direct it into one or more paths leading up through the heater and then down to emerge at or near the base of the heater.

2. A heater as claimed in claim 1, wherein the stream of air is drawn in through an opening or openings in the side walls of the heater, and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Gas-fired heater This invention relates to gas-fired heaters of the kind where a fan assists the flow of convection air to be heated through the heater. Such'heaters will be termed hereinafter "heaters of the kind described". The invention provides a heater of the kind described wherein the fan draws in convection air at or near the base of the heater and directs it into one or more paths leading up through the heater and then down to emerge at or near the base of the heater. Preferably said heater includes a combustion chamber, one or more of the said paths comprising a hot air path leading convection air over said combustion chamber to be heated thereby and another of said paths comprising a cool air path lying adjacent exterior walls of the heater and not contacting said combustion chamber. The heater may have a heat exchanger spaced from but connected to the combustion chamber to receive combustion products therefrom, and another of said paths comprising a second hot air path may lead convection air into contact with said heat exchanger, said cool air path not contacting said heat exchanger. The cool air path may be defined by a divider plate separating it from the other paths and may extend effectively around the exterior rear, top and front walls of the heater. A vent from the cool air path may direct air therefrom into a control compartment. A specific embodiment of the invention is shown in the accompanying drawing, which is a diagrammatic side section through a gas convector heater. The heater has a burner 11 in a combustion chamber 12, the exhaust products being directed down into a double pass heat exchanger 13 through a connection 14 before leaving the heater through flue 15. Combustion air is drawn in through duct 16 buy a fan 17. The flue 15 and duct 16 may terminate in a balanced flue arrangement (not shown). The heater heats room air which is drawn in through low-level vents 18 by a tangential fan 20. The incoming air is divided into three paths. A first path shown by arrows A flows between the combustion chamber 12 and the heat exchanger 13, and since these parts are the hottest, air flowing in this path reaches the highest temperature. A second path shown by arrows B flows between the heat exchanger 13 and a divider plate 21. Air following this path becomes hot but not as hot as that in the first path. The third path shown by arrows C flows between the divider plate 21 and the rear of the heater. The divider plate extends across the top of the heater to a point adjacent the front of the heater, at which point the three flows are not longer separated and begin to mix. The third flow has not contacted the heat exchanger or the combustion chamber and is therefore coolerthan the other two flows. From the top of the heater the three flows are then directed downwardly adjacent the front of the heater and finally emerge from a low-level grill 23. Although mixing of the flows begins at the beginning of this final downward pass, the cool air of the third flow tends to remain in contact with the outer wall. It will be seen from the figure that in effect the heater is encased in the cool air of the third flow and this maintains the outer casing of the heater at a lower temperature than would otherwise be the case. It is found that the casing never reaches an uncomfortably hot temperature in practice in spite of the high interior temperature of the heater. Moreover, because the heated air emerges at the lower level, the room is more evenly heated, the tendency to a layer of cold air being formed at ground level being avoided. To increase further the comfort level in use, the heat is fitted with a thermostatic switch (not shown) which prevents the fan 20 from operating until a temperature sensor at the top of the heat exchanger indicates that hot air is available. This avoids an initial blowing of cold air into the room while the heater warms up. The cool third air flow is also used to cool the control circuits of the heater (not shown) which control the automatic starting and stopping of the heater under the influence of an integral thermostat and also of a timing clock. The electronic controls are mounted at one side of the heater and vents 24 direct a part of the cool air into a compartment housing the controls. A further refinement is a series of vertical guides 25 adjacent the grill 23. These can be adjusted by rotating about their horizontal axes so as to direct the emerging hot air to a selected preferred area of the room. The guides may be adjusted once and for all when the heat is installed or an external slide controi may allow the user to altertham at will. Yet another refinement is the inclusion of a humidifier (not shown). This comprises a wick kept wetted by a water reservoir (not shown), the wick extending into the hot air stream. The integral thermostat has a main phial 26 which senses the temperature of the incoming cool air stream and operates to turn the heater off when a predetermined temperature is reached. This arrangement by itself tends to overshoot the predetermined temperature since hot air continues to be blown into the room until the thermostat operates. A secondary phial 26' is therefore positioned in the hot air stream to provide a degree of anticipation of the effect of the hot air on the room temperature. The phial 26' when it senses hot air advances the operation of the main phial 26 to turn the heater off. Similarly, when the heater cools down after being turned off, phial 26' anticipates the operation of the main phial to turn the heater on. CLAIMS

2. A heater as claimed in claim 1, wherein the stream of air is drawn in through an opening or openings in the side walls of the heater, and emerges through an opening or openings in a front wall of the heater.

3. A heater as claimed in claim 1 or claim 2, including a combustion chamber, one of said paths comprising a first path leading air into contact with a surface of said combustion chamber and another of said paths comprising a cool air path leading to adjacent exterior walls of the heater and not contacting the surface of said combustion chamber.

4. A heater as claimed in claim 3, wherein said cool air path is at least partially defined between a divider plate, which separates it from the other path or paths, and an exterior wall of the heater, the said cool air path extending upwards adjacent the back, across the top and down over the front wall of the heater.

5. A heater as claimed in claim 4, wherein said divider plate extends upwards spaced from a back wall of the heater and across the top of the heater spaced from the top wall, the said cool air path being in contact with the other path or paths as it extends downwards adjacent the front wall of the heater.

6. A heater as claimed in any of claims 3 to 5, including a heat exchanger spaced from but connected to the combustion chamber to receive combustion products therefrom, said first path leading air between the combustion chamber and one side of the heat exchanger, and another of said paths leading air into contact with the other side of the heat exchanger.

7. A heater as claimed in claim 6 wherein said first path and said other path contact one another at the top of the heat exchanger.

8. A heater as claimed in any of claims 3 to 7, including controls housed in a compartment at one side of the heater, there being means for allowing a flow of air from said cool air path to enter said compartment.

9. A heater as claimed in claim 2 or any of claims 3 to 8, as appendant to claim 2, wherein there is adjustable guide means adjacent the opening or openings in thefrontwall whereby the emerging stream of air may be directed in a selected direction.

10. A heater as claimed in claim 8, wherein said controls include switch means for turning the heater on and off to maintain a predetermined temperature, the temperature being sensed by a pair of phials, one located in the incoming stream of air and the other located in the outgoing stream of air.

11. A heater of the kind described substantially as described hereinbefore with reference to the accompanying drawing.