CA1298749B - Flue Restrictor - Google Patents
Flue RestrictorInfo
- Publication number
- CA1298749B CA1298749B CA615986A CA615986A CA1298749B CA 1298749 B CA1298749 B CA 1298749B CA 615986 A CA615986 A CA 615986A CA 615986 A CA615986 A CA 615986A CA 1298749 B CA1298749 B CA 1298749B
- Authority
- CA
- Canada
- Prior art keywords
- sub
- flue
- restrictor
- housing
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L13/00—Construction of valves or dampers for controlling air supply or draught
- F23L13/06—Construction of valves or dampers for controlling air supply or draught slidable only
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Regulation And Control Of Combustion (AREA)
Abstract
Abstract A flue restrictor controls air flow in a combustion apparatus having an exhaust system that includes a flue.
The restrictor comprises a housing to be attached in the flue and comprising a first sub-housing and a second sub-housing having continuous, imperforate side walls. A first valve member is secured to the first sub-housing and a second valve member is secured to the second sub-housing. The sub-housings are positioned with the valve members located adjacent each other, so that the rotation of the sub-housings relative to each other causes the valve members to rotatably cooperate with each other to act as a valve. The sub-housings are enlarged relative to the flue, so that when the valve is opened, flow through the restrictor is the same as flow through the unrestricted flue.
The restrictor comprises a housing to be attached in the flue and comprising a first sub-housing and a second sub-housing having continuous, imperforate side walls. A first valve member is secured to the first sub-housing and a second valve member is secured to the second sub-housing. The sub-housings are positioned with the valve members located adjacent each other, so that the rotation of the sub-housings relative to each other causes the valve members to rotatably cooperate with each other to act as a valve. The sub-housings are enlarged relative to the flue, so that when the valve is opened, flow through the restrictor is the same as flow through the unrestricted flue.
Description
Flue Restrictor FIELD OF THE INVENTION
This invention relates to a flue restrictor to control air flow in a combustion apparatus, usually a furnace, boiler S or water heater.
DESCRIPTION OF THE PRIOR ART
The gas or oil burning furnace that finds wide application in central heating systems in the United States and Canada is a commendably efficient mechanical device.
In the Northern United States and Canada such a furnace will ~--typically be in daily use for six months of the year. Yet for the first ten or fifteen years of its life the onIy maintenance that is necessary is usually the occasional application of a small amount of lubricating oil and the annual changing of the filter.
From a combustion point of view the furnace is less commendable. When tested under laboratory conditions the typical efficiency is about 80% but field tests of a typical ~urnace boiler or water heater show that the actual working e~ficiency is closer to 50%. However, even here the fault lies not with the furnace but with the exhaust or venting system through which the combusted gases pass to atmosphere.
It has been recognized for some time that this efficiency loss stems from the venting system allowing too much air to flow through the appliance.
When a combustion device is running, the gases flow from a combustion chamber, through a heat exchanger, into the flue and then into the atmosphere. Air is fed to the combustion chamber for the combustion, but the air fed is not in any way controlled in the usual combustion apparatus and this is the basis of the problem. Excess air lowers the temperature of the flue gases flowing through the heat exchanger.
Furthermore, the greater the draft of the flue then the more air is present to dilute that used by the burner and less heat reaches the heat exchanger.
~Z98749 The excess air introduced is also undesirable in the actual combustion step. The excess air upsets the desirable ratios for combustion so that unburned fuel escapes into the flue.
Even when the combustion apparatus is not in operation air can still flow rapidly through the furnace causing a further 105s of heat by taking heat from the apparatus as well as from the surroundings and exhausting that heat up the flue.
It is therefore clear that excess air flow through the combustion apparatus is undesirable. What is desirable is an optimum flow, able to support combustion at the maximum possible level and not so great that inefficient combustion ~--and heat loss are induced.
Attempts at solving the above problems include those set lS out in Canadian patents 1,119,497 and 1,134,229.
Unfortunately these devices, although obviously helping to solve the problem, do so in a relatively unsatisfactory way. In particular, although they are adjustable, the adjustment means is relatively imprecise and the actual adjusting step laborious. Although they act to restrict the air flow through the combustion apparatus, they do so in a way that cannot be fine tuned for an individual apparatus.
~ARY OF THE INVENTION
~he present invention seeks to provide an apparatus in 25 which fine tuning of the air flow through the combustion --apparatus can be achieved.
Accordingly the present invention provides a flue restrictor to control air flow in a combustion apparatus having an exhaust system that includes a flue, the restrictor comprising a housing to be attached in the flue and comprising a first sub-housing and a second sub-housing having continuous, imperforate side walls; a first valve member secured to the first sub-housing; a second valve member secured to the second sub-housing; the sub-housings being rotatable relative to each other and positioned with the first and second valve members located so as to rotatably cooperate with each other to act as a valve; the sub-housings being enlarged relative to the flue so that when the valve is opened flow through the restrictor is the same as flow through the unrestricted flue.
DRAWINGS
Aspects of the invention are illustrated, merely by way of example, in the accompanying drawings in which:
Figure 1 is a general view of a furnace fitted with a flue restrictor;
Figure 2 is a section on the line 2-2 in Figure l;
Figures 3 and 4 illustrate valve members; and Figure 5 illustrates an embodiment of the invention as applied to a flue restrictor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings Figure 1 shows a conventional furnace 2 having an air inlet 4. No details of the interior of the furnace are shown. They are entirely conventional. The furnace is fitted with a vent 6, typically a five, six or seven inch pipe. Only the first part of the vent, generally known as the flue, is shown in Figure 1. Further, although a furnace is shown; the restrictor is useful with related devices, such as water heaters and boilers.
In the flue 6 a restrictor 8 is attached.
As shown in more detail in Figure 2 the restrictor 8 comprises a housing 10 attached in the flue 6. The housing 10 comprises end pieces 12 having projections 14 to engage flue 6. In accordance with conventional practice the upstream (lower) projection fits outside the flue 6 and the downstream (upper) projection 14 fits within the flue 6 to facilitate gas flow.
There is a valve 16 associated with the housing 10.
In the construction illustrated in Figure 2 the valve comprises a first valve member 18 that is fixed within the housing 10 by flaps 20 that are attached to the housing 10 by spot welding. The valve is shown in Figure 3. A second or lower valve member 22 is pivotable within the housing 10 and, as shown most clearly in Figure 3, a lever 24 extends ~Z98749 outwardly from the valve member 22 to extend out from the housing 10. The lever 24 extends through a slot 26 in the housing 10.
As shown particularly in Figure 3 each valve member 18 and 22 comprises a plate. In the embodiment of Figure 3 the plate has a central opening 28 formed within an inner ring 30.
Discrete fins 32 extend outwardly from the inner ring 30 and there are spaces 34 between each fin 32. Generally speaking the area of a fin 32 is the same as the area of a space 34.
The second valve member 22 is generally the same as the first valve member 18 and differs only by having the lever 24 and being without tabs 20, although a single tab 36 is desirable `-to assist in keeping the valve member 22 aligned in the housing 10.
The arrangement of fins 32 and spaces 34 ensures that as the valve member 22 is rotated the valve moves from a fully open position, the solid line position shown in Figure 3, to a ~ully closed position, the broken line position for the lower valve member 22 in Figure 3.
The construction of Figure 4 differs from that of Figure 3 by the provision of a central hub 38 for each valve member.
Discrete fins 40 extend outwardly from the central hub 38 and there are spaces 42 between each fin 40. Again the fully open position is shown in solid lines in Figure 4, and the fully closed position is shown by the use of broken lines for the lower valve member in Figure 4. The tabs 20 and 36 are as in the Figure 3 valve member.
The embodiment of the invention shown in Figure 5 differs from the construction of Figure 2 in comprising an upper sub-housing 41 and a lower sub-housing 43 that are rotatable relative to each other. Each sub-housing has located within it a valve member, for example as shown in Figure 3 or 4.
However, unlike the Figure 2 embodiment, each valve member is secured within its respective sub-housing, for example by the provision of flaps 44 that are riveted to the respective sub-housings. There is a bead 46 provided on the lower sub-housing 43 to control the depth of telescoping of the housings lZ98749 41 and 43 and, in particular, to ensure the proper location of the valve members. This arrangement avoids the need for the lever 24 projecting through the slot 26 and hence enables the sub-housings to have, as shown, continuous imperforate side walls.
It should be noted that the restrictor 8 is larger in cross section than the flue 6 that receive the restrictor.
This is done to ensure that when the valve members are in the fully opened position the flow through the flue restrictor is the same as flow through the unrestricted flue, i.e. as though the flue restrictor were not present.
The restrictor of the present invention is useful either in existing heating systems, or, may, of course, be installed when the heating system is installed. Installation is simple.
The existing system is cut and part of the exhaust system removed, sufficient to enable the device according to the present invention to be inserted. The device may be screwed or riveted in position, using conventional techniques.
Typically screws or rivets will be inserted at the overlapping parts of the system at the top and bottom of the restrictor.
Once the device is installed the sub-housings are rotated to fully open the valve, i.e. so that the flow through the restrictor is at its maximum. A draught reading is taken, using a conventional flow meter, below the restrictor 8. If the draught is excessive, as would be the case in a conventional system, one sub-housing is rotated relative to the other so that the valve opening is adjusted to ensure at least partial overlap of the fins. This decreases the draught and thus the air supply. When optimum efficiency is reached the sub-housings are each located within the exhaust system, for example by riveting.
The optimum flow for highest efficiency for any one furnace can, of course, be determined from known figures.
Such information is available in tables produced by various authorities.
Assuming that the construction of Figure 3 is used, it has been found desirable to arrange the area of the spaces Ei749 34 of the valve members 18 and 22 to ensure that flow through the restrictor can vary from 30% to 100% of the flow through an unrestricted exhaust system. Of course figures above 100%
flow through the restrictor can be reached but there is no point in exceeding that figure. Figures below 30% are usually prohibited by local authorities, since below that figure exhaust fumes can easily be forced back into the building.
The present invention reduces excess air flow through a furnace. Only the optimum amount of air for combustion is allowed to flow. Furthermore, when the burners are switched off the flow is restricted and losses of heat due to draught are thus reduced. When the furnace is not combusting, the heat loss is not as rapid, because the air flow is not as rapid.
The illustrated devices may be made of the usual galvanized sheet metal common in gas fittings.
This invention relates to a flue restrictor to control air flow in a combustion apparatus, usually a furnace, boiler S or water heater.
DESCRIPTION OF THE PRIOR ART
The gas or oil burning furnace that finds wide application in central heating systems in the United States and Canada is a commendably efficient mechanical device.
In the Northern United States and Canada such a furnace will ~--typically be in daily use for six months of the year. Yet for the first ten or fifteen years of its life the onIy maintenance that is necessary is usually the occasional application of a small amount of lubricating oil and the annual changing of the filter.
From a combustion point of view the furnace is less commendable. When tested under laboratory conditions the typical efficiency is about 80% but field tests of a typical ~urnace boiler or water heater show that the actual working e~ficiency is closer to 50%. However, even here the fault lies not with the furnace but with the exhaust or venting system through which the combusted gases pass to atmosphere.
It has been recognized for some time that this efficiency loss stems from the venting system allowing too much air to flow through the appliance.
When a combustion device is running, the gases flow from a combustion chamber, through a heat exchanger, into the flue and then into the atmosphere. Air is fed to the combustion chamber for the combustion, but the air fed is not in any way controlled in the usual combustion apparatus and this is the basis of the problem. Excess air lowers the temperature of the flue gases flowing through the heat exchanger.
Furthermore, the greater the draft of the flue then the more air is present to dilute that used by the burner and less heat reaches the heat exchanger.
~Z98749 The excess air introduced is also undesirable in the actual combustion step. The excess air upsets the desirable ratios for combustion so that unburned fuel escapes into the flue.
Even when the combustion apparatus is not in operation air can still flow rapidly through the furnace causing a further 105s of heat by taking heat from the apparatus as well as from the surroundings and exhausting that heat up the flue.
It is therefore clear that excess air flow through the combustion apparatus is undesirable. What is desirable is an optimum flow, able to support combustion at the maximum possible level and not so great that inefficient combustion ~--and heat loss are induced.
Attempts at solving the above problems include those set lS out in Canadian patents 1,119,497 and 1,134,229.
Unfortunately these devices, although obviously helping to solve the problem, do so in a relatively unsatisfactory way. In particular, although they are adjustable, the adjustment means is relatively imprecise and the actual adjusting step laborious. Although they act to restrict the air flow through the combustion apparatus, they do so in a way that cannot be fine tuned for an individual apparatus.
~ARY OF THE INVENTION
~he present invention seeks to provide an apparatus in 25 which fine tuning of the air flow through the combustion --apparatus can be achieved.
Accordingly the present invention provides a flue restrictor to control air flow in a combustion apparatus having an exhaust system that includes a flue, the restrictor comprising a housing to be attached in the flue and comprising a first sub-housing and a second sub-housing having continuous, imperforate side walls; a first valve member secured to the first sub-housing; a second valve member secured to the second sub-housing; the sub-housings being rotatable relative to each other and positioned with the first and second valve members located so as to rotatably cooperate with each other to act as a valve; the sub-housings being enlarged relative to the flue so that when the valve is opened flow through the restrictor is the same as flow through the unrestricted flue.
DRAWINGS
Aspects of the invention are illustrated, merely by way of example, in the accompanying drawings in which:
Figure 1 is a general view of a furnace fitted with a flue restrictor;
Figure 2 is a section on the line 2-2 in Figure l;
Figures 3 and 4 illustrate valve members; and Figure 5 illustrates an embodiment of the invention as applied to a flue restrictor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings Figure 1 shows a conventional furnace 2 having an air inlet 4. No details of the interior of the furnace are shown. They are entirely conventional. The furnace is fitted with a vent 6, typically a five, six or seven inch pipe. Only the first part of the vent, generally known as the flue, is shown in Figure 1. Further, although a furnace is shown; the restrictor is useful with related devices, such as water heaters and boilers.
In the flue 6 a restrictor 8 is attached.
As shown in more detail in Figure 2 the restrictor 8 comprises a housing 10 attached in the flue 6. The housing 10 comprises end pieces 12 having projections 14 to engage flue 6. In accordance with conventional practice the upstream (lower) projection fits outside the flue 6 and the downstream (upper) projection 14 fits within the flue 6 to facilitate gas flow.
There is a valve 16 associated with the housing 10.
In the construction illustrated in Figure 2 the valve comprises a first valve member 18 that is fixed within the housing 10 by flaps 20 that are attached to the housing 10 by spot welding. The valve is shown in Figure 3. A second or lower valve member 22 is pivotable within the housing 10 and, as shown most clearly in Figure 3, a lever 24 extends ~Z98749 outwardly from the valve member 22 to extend out from the housing 10. The lever 24 extends through a slot 26 in the housing 10.
As shown particularly in Figure 3 each valve member 18 and 22 comprises a plate. In the embodiment of Figure 3 the plate has a central opening 28 formed within an inner ring 30.
Discrete fins 32 extend outwardly from the inner ring 30 and there are spaces 34 between each fin 32. Generally speaking the area of a fin 32 is the same as the area of a space 34.
The second valve member 22 is generally the same as the first valve member 18 and differs only by having the lever 24 and being without tabs 20, although a single tab 36 is desirable `-to assist in keeping the valve member 22 aligned in the housing 10.
The arrangement of fins 32 and spaces 34 ensures that as the valve member 22 is rotated the valve moves from a fully open position, the solid line position shown in Figure 3, to a ~ully closed position, the broken line position for the lower valve member 22 in Figure 3.
The construction of Figure 4 differs from that of Figure 3 by the provision of a central hub 38 for each valve member.
Discrete fins 40 extend outwardly from the central hub 38 and there are spaces 42 between each fin 40. Again the fully open position is shown in solid lines in Figure 4, and the fully closed position is shown by the use of broken lines for the lower valve member in Figure 4. The tabs 20 and 36 are as in the Figure 3 valve member.
The embodiment of the invention shown in Figure 5 differs from the construction of Figure 2 in comprising an upper sub-housing 41 and a lower sub-housing 43 that are rotatable relative to each other. Each sub-housing has located within it a valve member, for example as shown in Figure 3 or 4.
However, unlike the Figure 2 embodiment, each valve member is secured within its respective sub-housing, for example by the provision of flaps 44 that are riveted to the respective sub-housings. There is a bead 46 provided on the lower sub-housing 43 to control the depth of telescoping of the housings lZ98749 41 and 43 and, in particular, to ensure the proper location of the valve members. This arrangement avoids the need for the lever 24 projecting through the slot 26 and hence enables the sub-housings to have, as shown, continuous imperforate side walls.
It should be noted that the restrictor 8 is larger in cross section than the flue 6 that receive the restrictor.
This is done to ensure that when the valve members are in the fully opened position the flow through the flue restrictor is the same as flow through the unrestricted flue, i.e. as though the flue restrictor were not present.
The restrictor of the present invention is useful either in existing heating systems, or, may, of course, be installed when the heating system is installed. Installation is simple.
The existing system is cut and part of the exhaust system removed, sufficient to enable the device according to the present invention to be inserted. The device may be screwed or riveted in position, using conventional techniques.
Typically screws or rivets will be inserted at the overlapping parts of the system at the top and bottom of the restrictor.
Once the device is installed the sub-housings are rotated to fully open the valve, i.e. so that the flow through the restrictor is at its maximum. A draught reading is taken, using a conventional flow meter, below the restrictor 8. If the draught is excessive, as would be the case in a conventional system, one sub-housing is rotated relative to the other so that the valve opening is adjusted to ensure at least partial overlap of the fins. This decreases the draught and thus the air supply. When optimum efficiency is reached the sub-housings are each located within the exhaust system, for example by riveting.
The optimum flow for highest efficiency for any one furnace can, of course, be determined from known figures.
Such information is available in tables produced by various authorities.
Assuming that the construction of Figure 3 is used, it has been found desirable to arrange the area of the spaces Ei749 34 of the valve members 18 and 22 to ensure that flow through the restrictor can vary from 30% to 100% of the flow through an unrestricted exhaust system. Of course figures above 100%
flow through the restrictor can be reached but there is no point in exceeding that figure. Figures below 30% are usually prohibited by local authorities, since below that figure exhaust fumes can easily be forced back into the building.
The present invention reduces excess air flow through a furnace. Only the optimum amount of air for combustion is allowed to flow. Furthermore, when the burners are switched off the flow is restricted and losses of heat due to draught are thus reduced. When the furnace is not combusting, the heat loss is not as rapid, because the air flow is not as rapid.
The illustrated devices may be made of the usual galvanized sheet metal common in gas fittings.
Claims (5)
1. A flue restrictor to control air flow in a combustion apparatus having an exhaust system that includes a flue, the restrictor comprising:
A housing to be attached in the flue and comprising a first sub-housing and a second sub-housing, both said sub-housings having continuous, imperforate side walls;
a first valve member secured to the first sub-housing;
a second valve member secured to the second sub-housing;
the sub-housings being rotatable relative to each other and positioned with the first and second valve members located so as to rotatably cooperate with each other to act as a valve;
the sub-housings being enlarged relative to the flue so that when the valve is opened flow through the restrictor is the same as flow through the unrestricted flue.
A housing to be attached in the flue and comprising a first sub-housing and a second sub-housing, both said sub-housings having continuous, imperforate side walls;
a first valve member secured to the first sub-housing;
a second valve member secured to the second sub-housing;
the sub-housings being rotatable relative to each other and positioned with the first and second valve members located so as to rotatably cooperate with each other to act as a valve;
the sub-housings being enlarged relative to the flue so that when the valve is opened flow through the restrictor is the same as flow through the unrestricted flue.
2. A restrictor as claimed in claim 1 in which the valve members each comprises a plate having a central opening defined within an inner ring, with discrete fins extending outwardly from the inner ring and spaces between each fin.
3. a restrictor as claimed in claim 1 in which each valve member has a central hub, with discrete fins extending outwardly from the central hub and spaces between each fin.
4. A restrictor as claimed in claim 2, wherein the central openings in each valve member are so dimensioned that when the valve is closed the flow through the aligned central openings is about 30% of the flow through the unrestricted flue.
5. A restrictor as claimed in claim 1, 2, 3 or 4, including means to lock the sub-housings in a predetermined relative position to control air flow in the restrictor and thus in the combustion apparatus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA615986A CA1298749B (en) | 1987-04-08 | 1991-01-25 | Flue Restrictor |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000534125A CA1247956A (en) | 1987-04-08 | 1987-04-08 | Flue restrictor |
| CA615986A CA1298749B (en) | 1987-04-08 | 1991-01-25 | Flue Restrictor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1298749B true CA1298749B (en) | 1992-04-14 |
Family
ID=25671302
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA615986A Expired - Lifetime CA1298749B (en) | 1987-04-08 | 1991-01-25 | Flue Restrictor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1298749B (en) |
-
1991
- 1991-01-25 CA CA615986A patent/CA1298749B/en not_active Expired - Lifetime
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4803931A (en) | Flue restrictor | |
| US5341795A (en) | Inducer for condensing furnace | |
| US6041771A (en) | Apparatus and method of automatically regulating intake of air into heating unit | |
| US4337892A (en) | Draft control arrangement for vent of combustion apparatus | |
| US4263890A (en) | Flue restrictor | |
| US5452708A (en) | Universal horizontal-vertical (H-V) direct-vented gas heating unit | |
| CA1130656A (en) | Vent control arrangement for combustion apparatus | |
| US4191326A (en) | Draft control arrangement for combustion apparatus | |
| CA1109349A (en) | Heat circulating fireplace | |
| US5380193A (en) | Apparatus for attaching manifold assembly to gas control assembly of furnace | |
| CA1298749B (en) | Flue Restrictor | |
| US4580546A (en) | Catalytic stove | |
| US4341344A (en) | Automatic draft controller | |
| US4159078A (en) | Draft control arrangement for combustion apparatus | |
| EP1318354A2 (en) | Enclosure for an infrared heater | |
| CA1247956A (en) | Flue restrictor | |
| US4373510A (en) | Venting system for oil or gas-fired appliances | |
| US4294401A (en) | Draft control arrangement | |
| GB2330899A (en) | Flue system | |
| US4249694A (en) | Draft control arrangement | |
| US4497310A (en) | Flue box with adjustable counterbalance cap | |
| US4437454A (en) | Mechanical draft controller with vent damper | |
| US2735385A (en) | De ascentiis | |
| US4154150A (en) | Chimney closure with damper | |
| US4259943A (en) | Fuel economizer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| NARE | Reissued | ||
| MKEX | Expiry |