The present embodiments generally relate to providing improved sealing of exhaust vents for fuel burning heating equipment.
Today's high efficiency heating equipment operates under a positive (above atmospheric pressure) vent pressure during operation. The high pressure comes from the use of high pressure fans used to push the combustion flue products through the equipment's heat exchanger.
There is generally a need for sealing the vents for this type of equipment when two or more heating units are commonly vented to the outside of a building. For example, if a first unit is operating, and second and third units are not operating, the flue gases from the first unit could flow into the other two heating units if the vent system is operating under a positive pressure. This potential flow of exhaust gases into the non-operating second and third units can cause equipment failures or leakage of flue gases into the occupied building space. Vent pressurization can occur due to wind loads or other changes to the building's exterior environment.
In prior assemblies, seals have been mounted onto the gate of the damper, and when sufficient amount of closure torque is applied to the gate, the seal deflects and seals against the gate stop of the damper. When the vent side of the damper gets pressurized, the left side of the gate is pressed against the gate stop. But, the right side of the gate is pushed away from the gate stop. This movement away from the gate stop reduces the pressure applied to the seal, which allows the applied air pressure to deflect the seal and allow leakage past the seal. This type of sealing method requires a high amount of torque, e.g., 128 in-oz of torque, to maintain minimal amount of leakage past the seal. Therefore, such prior attempts have generally been difficult or unsuccessful.
A flue damper comprises a damper gate having first and second sides, and first and second seal stops. In one embodiment, a first seal is mounted to the first side of the damper gate and has a free end in sealing engagement with the first seal stop under pressure conditions, while a second seal is mounted to the second side of the damper gate and has a free end in sealing engagement with the second seal stop under the pressure conditions. In one exemplary technique, when pressurization occurs in a vent, the first side of the damper gate presses the first seal against the first seal stop, and the second side of the damper gate applies pressure to the second seal causing it to expand and allowing it to maintain contact with the second seal stop.
In one example, the first seal generally comprises a C-shape having first and second opposing surfaces and an interior space disposed therebetween. The first surface of the first seal may be mounted to the first side of the damper gate, and the free end of the first seal may be on the second surface and points in a radially outward direction away from an inside of a pipe. Alternatively, the free end of the first seal may point in a radially inward direction towards an inside of a pipe. The second seal also generally may comprise a C-shape having first and second opposing surfaces and an interior space disposed therebetween, wherein the first surface of the second seal is mounted to the second side of the damper gate, and the free end is on the second surface and points in a radially inward direction towards an inside of a pipe.
The flue damper further comprises a shaft seal, wherein the first and second seal stops may extend from the shaft seal. The shaft seal may comprise at least one slot that receives at least a portion of the damper gate. At least one of the first or second seal stops may have an end region that comprises the same radius of curvature as an exterior surface of the shaft seal.
In an alternative embodiment, the first seal is mounted to the first seal stop and has a free end in sealing engagement with the first side of the damper gate under pressure conditions, while the second seal is mounted to the second seal stop and has a free end in sealing engagement with the second side of the damper gate under the pressure conditions.
Advantageously, the present embodiments allow for limited air leakage past the damper with low spring pressure holding the damper closed. This differs from prior designs that utilize high spring pressure to hold the damper closed. Notably, the designs use the applied pressure in the vent to hold the damper closed and increase the sealing force.
Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims.
The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.
Referring to
Referring to
The flue damper 20 generally comprises a shaft seal 22, a damper gate 24 extending from the shaft seal 22, first and second seal stops 30a and 30b, and first and second seals 40a and 40b. In this example, the first seal 40a is mounted to an outer region of the first seal stop 30a, while the second seal 40b is mounted to an outer region of the second seal stop 30b, as shown in
The flue damper 20 has a sealed state in which a first side 24a of the damper gate 24 sealingly abuts the first seal 40a mounted to the first seal stop 30a, and where a second side 24b of the damper gate 24 sealingly abuts the second seal 40b mounted to the second seal stop 30b. As will be explained more fully below, when the vent is pressurized, the first side 24a of the damper gate 24 is pressed against the seal 40a. Further, in this embodiment, when pressure is applied to the second side 24b of the damper gate 24, and the second side 24b moves away from the second seal 40b, the second seal 40b expands from the pressurization of the internal portion of the seal, allowing it to maintain contact with the damper gate 24. In this state, flow through the pipe 18 at the damper 20 is substantially or entirely precluded.
The flue damper 20 further has an open state in which the damper gate 24 is rotated circumferentially, in this example in a clockwise direction, such that the first and second sides 24a and 24b of the damper gate 24 are no longer in sealing engagement with their respective seals 40a and 40b. In this latter state, venting of gases through the damper 20 is permitted.
It should be noted that various pressure forces may occur within the pipe 18 during the sealed state. For example, a pressure P1 may be applied by vent pipe pressurization in the direction depicted in
In the embodiment of
Further, in the embodiment of
Referring to
In both the embodiments of FIGS, 2-3, the pressure P2 applied by the first side 24a of the damper gate 24 pressing against the first seal 40a of
Referring now to
The seals 140a and 140b of FIGS.
In the embodiment of FIGS.
Notably, to the extent that pressure P1 from the vent is directed into the interior spaces 143a and 143b of the first and second seals 140a and 140b, as depicted in
Advantageously, the designs of the present embodiments use the applied pressure in the vent to hold the damper closed and increase the sealing force, thereby allowing for limited air leakage past the damper with low spring pressure holding the damper closed. This differs from prior designs that utilize high spring pressure to hold the damper closed. As a further advantage, such seal designs allow for molding the seal thicker, which makes them moldable at a lower cost and with fewer potential problems removing the seal from the mold.
Referring to
Referring now to
Looking at the performance of the “Proto 5a” sample leakage at 16 in-oz of closure torque, it starts leaking around 2.5 inches of water pressure, which yields a 400% increase in leakage resistance relative to the prior technique of the “Proto 5” sample. Nearly doubling the torque to 30 in-oz of closure torque increases the leakage applied pressure to around 5 inches of water pressure, which yields a 400% increase in leakage resistance relative to the prior technique of the “Proto 5” sample.
To verify the operation of the seal method of FIGS.
Referring now to
As noted above, the present embodiments advantageously allow for limited air leakage past the damper with low spring pressure holding the damper closed, as reflected in the data of
While various embodiments of the invention have been described, the invention is not to be restricted except in light of the attached claims and their equivalents. Moreover, the advantages described herein are not necessarily the only advantages of the invention and it is not necessarily expected that every embodiment of the invention will achieve all of the advantages described.
This invention claims the benefit of priority of U.S. Provisional Application Ser. No. 61/675,209, entitled “Low Leakage Flue Damper For Positive Pressure Heating Appliance Venting System,” filed Jul. 24, 2012, the disclosure of which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
61675209 | Jul 2012 | US |