Note: Descriptions are shown in the official language in which they were submitted.
CA 02708756 2013-09-20
METHOD AND KIT FOR PASSIVELY EQUALIZING AIR PRESSURES WITHIN A HOUSE
AND/OR AIR PRESSURE INSIDE A HOUSE WITH AIR PRESSURE OUTSIDE A HOUSE
FIELD OF THE INVENTION
The present invention relates to Heating, Ventilation and Air Conditioning
(HVAC) technologies.
In particular, the present invention relates to a method of equalizing air
pressures within a house
and/or air pressure inside a house with air pressure outside a house utilizing
an auxiliary duct
connected to an existing exhaust stack of a combustion appliance, such as, for
example, a
furnace or water heater tank.
BACKGROUND OF THE INVENTION
Generally, a house is heated in cold climates by way of a furnace in which a
combustible product,
such as, for example, natural gas, oil or wood/coal is combusted in a
combustion chamber and
the heat produced is moved throughout the house in a number of different ways.
The combustion
byproducts escape from the combustion chamber and outside of the home by way
of an exhaust
pipe connected to a flue or a chimney or the like. To control the combustion
rate and ensure
efficient combusting conditions in the combustion chamber, secondary air flow
is provided to
the exhaust pipe by way of a duct that intersects the exhaust pipe having a
swinging type damper
to control the secondary air flow through the duct.
A phenomenon called "negative pressure" is created in a house that lacks a
readily available
source of fresh air and is caused by having more air exit the house than is
being replenished.
Some of the sources of having too much air exit the house are exhaust fans
operating and
combustion appliances. Another cause of this phenomenon is from heated air
rising in the house
and creating a negative pressure on lower levels.
Another cause of negative pressure is the imbalance between inside air
pressure and outside air
pressure from wind. Wind blowing on the windward side of a house causes a
region of positive
pressure and a region of negative pressure on the leeward sides parallel to
the flow.
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In certain situations where the inside pressure of the house drops, for
example by the negative
pressure phenomenon, or the heat of the combustion byproducts is insufficient
to maintain the
outward flow of the byproducts through the flue or chimney, it is possible for
the flow to reverse
and the combustion byproducts be released into the house, this phenomenon is
known as "back
drafting".
A draft is created in an exhaust stack by the buoyancy of the combustion
byproducts, a different
draft is created in the house due to the differences in temperature between
the air inside the
house and the air outside the house. The warmer air inside the house tends to
rise since it is less
dense and warmer than the air outside the house.
The tendency of the warmer house air to rise results in air pressure
differences at various levels
in the house. The air pressure in lower levels of the house will be less than
the atmospheric
pressure. The air pressure in upper levels of the house will be higher than
the atmospheric
pressure, since the rising air pushes against the ceiling and accumulates. At
a certain location
between the higher air pressure area and lower air pressure area, the air
pressure will be equal
to the atmospheric pressure.
The equal atmospheric pressure point is called the "neutral pressure plane".
The variation in air
pressure at different levels of the house is called the "stack effect". The
taller the house is, the
greater the stack effect will be. The stack effect in a house can make a
considerable difference
in the venting and performance of combustion appliances such as a furnace or
water heater tank.
Accordingly, there exists a need for a method of easily and efficiently
equalizing air pressures
within a house and/or air pressure inside a house with air pressure outside a
house and to reduce
the effects of the stack effect. Prior art methods and devices have not
adequately addressed this
problem.
United States Patent No. 4,633,768, issued January 6, 1987 (Benson) discloses
a device that
comprises a supplemental ventilation apparatus. In one of the embodiments, the
invention
discloses the ventilation system for a gas burner furnace comprising the
conventional central
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flue for combustion gases release and an inlet air tube which introduces
outside air into the
furnace.
Canadian Patent No. 1,175,721, issued October 10, 1984 (Newell) discloses a
method for
increasing the efficiency of a heating system that comprises a furnace, an
exhaust pipe to
remove the combustion gases extending from the combustion chamber of the
furnace to the
exterior of the building and an auxiliary duct intersecting the exhaust pipe
to permit air to flow
from the interior of the building to the exhaust pipe. The flow through the
auxiliary duct is
controlled in part by a damper and additionally, shut-off valves.
United States Patent No. 4,920,866, issued May 1, 1990 (Hoban) discloses an
improved
combustion arrangement meant to prevent the back draft in a flue due to the
negative pressure
in the house. The invention deals with the back draft by adding an additional
duct connected to
the flue through a nozzle arranged to inject air into the flue in forward
direction. Before being
injected into the flue, the air is heated and then forced into the flue by a
fan.
Canadian Patent No. 681,043, issued February 25, 1964 (Field) discloses a
furnace system
utilizing separate flue pipes for introducing combustion air and exhausting
smoke at the exterior
of a building. Field also discloses a cap structure for used at the exterior
ends of the flue pipes.
United States Patent No. 4,262,608, issued April 21, 1981 (Jackson) discloses
an assembly of
powered exhaust flue and preheated combustion air supply for use in
association with a heating
furnace so that the flue gases are exhausted to the outside while a balanced
combustion air
supply is pulled inside. The exhaust pipe is concentrically positioned within
the outside air
intake pipe. Both the exhaust and the air intake pipes are controlled by
dampers. The flow of
exhaust gases and fresh intake air is controlled by means of fans installed
inside the two pipes.
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SUMMARY OF THE INVENTION
The present invention provides a method of equalizing air pressures within a
house and/or air
pressure inside a house with air pressure outside a house to reduce the
effects of the stack effect
utilizing an auxiliary duct connected to the existing flue chimney and intake
air from another
area. The present invention also provides a kit to perform the method.
As an aspect of the present invention, there is provided a method to install a
system for
equalizing air pressures within a house. The method comprises the steps of
affixing an auxiliary
air supply means to an existing exhaust stack of an existing combustion device
located in an area
with an air pressure that is lower than an atmospheric air pressure and
supplying the auxiliary air
supply means with air via an aperture located in an area with an air pressure
that is equal or
higher than the atmospheric air pressure. Preferably, the method comprises the
step of controlling
an air flow through the auxiliary air supply means by way of a damping means.
As another aspect of the present invention, there is provided a kit for
carrying out the method as
described above. The kit comprises a series of duct for supplying air via an
open end of the series
of duct from an area of air pressure that is equal or higher than an
atmospheric air pressure, a
means for affixing an other end of the series of duct to an existing exhaust
stack and a damping
means for controlling a flow of air through the series of duct. Preferably,
the kit comprises a
directional damper for controlling a flow of air through the series of duct.
Also preferable, the
kit comprises a one way directional vent for ensuring that air flows only into
the open end of the
series of duct.
As another aspect of the present invention, there is provided a system for
passively equalizing
air pressures within a house, the system comprising: a passive auxiliary air
supply means affixed
to an existing exhaust stack of an existing combustion device located in an
area with an air
pressure that is lower than an atmospheric air pressure; and a passive
aperture located in an area
with an air pressure that is equal or higher than the atmospheric air pressure
to passively supply
the passive auxiliary air supply means with air.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will be further described, by way of
example, with
reference to the accompanying drawings, in which:
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Figures la and lb are perspective views of a standard natural gas fueled
furnace and water
heater tank;
Figure 2 depicts a house affected by the stack effect; and
Figure 3 depicts a house using the method and/or kit according to an
embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A better understanding of the present invention and its objects and advantages
will become
apparent to those skilled in this art from the following detailed description,
wherein there is
described only the preferred embodiment of the invention, simply by way of
illustration of the
best mode contemplated for carrying out the invention. As will be realized,
the invention is
capable of modifications in various obvious respects, all without departing
from the scope and
spirit of the invention. Accordingly, the description should be regarded as
illustrative in nature
and not as restrictive.
Figures la and lb show a standard natural gas fueled furnace (1) and water
heater tank (2).
Typically, a furnace (1) has a return register (3), a supply register (4), a
gas supply line (5), an
exhaust stack (6), and a secondary air flow (7). The gas supply line (5)
provides fuel for the
furnace (1), the fuel combusts in the combustion chamber (not shown) of the
furnace (1) and
heats the air in a heat exchanger (not shown) that is sucked in from the
return register (3), the
heated air is then blown out of the supply register to provide heat to rest of
the house.
Combustion by products, such as, for example, carbon monoxide, escape from the
combustion
chamber via the exhaust stack (6).
Similarly, a water heater tank (2) has a cold water inlet (8), a hot water
outlet (9), a gas supply
line (5), an exhaust stack (6), and a secondary air flow (7). The gas supply
line (5) provides fuel
for the water heater tank (2), the fuel combusts and heats the water in the
water tank (3), the
heated water is then available to be used throughout the house. Combustion by
products escapes
via the exhaust stack (6).
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Now referring to Figures 2 and 3. The exhaust stack (6) is connected to a flue
or chimney (10)
which allows combustion byproducts from the furnace (1) or water heater tank
(2) to be released
through an exterior wall and out of the house. Generally, combustion in the
furnace (1) or water
heater tank (2) is sufficient to generate an updraft through the flue or
chimney (10) so that the
combustion gases are drawn away from the furnace (1) or water heater tank (2)
to sustain
combustion and to ensure that no combustion byproducts remain in the house.
Figure 2 depicts a house (11) having a combustion appliance (12) that is
affected by the stack
effect. The arrows denote warm inside air rising in the house (11) and the
pressure gauges
denote relative air pressures in the house (11) and outside the house (11), a
clockwise movement
of the needle represents a higher relative air pressure and a counter-
clockwise movement of the
needle represents a lower relative air pressure. As can be seen in figure 2
the upper area of the
house (11) has a relative air pressure that is higher than the outside
atmospheric pressure and
the lower area of the house (11) has a relative air pressure that is lower
than the outside
atmospheric pressure. At a point between the higher air pressure and the lower
air pressure the
air pressure inside the house (11) is equal to the outside atmospheric air
pressure, i.e. the neutral
pressure plane.
Figure 3 depicts a house (13) having a combustion appliance (12) that is using
the method
and/or kit according to the present invention to reduce the stack effect. As
can be seen in figure
3, the air from areas of higher relative pressure (above the neutral pressure
plane) is being drawn
down into the auxiliary air supply means (14) via an aperture (15) into the
areas of lower
relative pressure (below the neutral pressure plane). Accordingly, if the air
is drawn from upper
areas of the house (13), the air pressure in the upper areas of the house (13)
is lowered and the
air pressure in the lower areas of the house (13) is increased, thus the air
pressures in the house
(13) are more closely equalized to that of the outside atmospheric pressure
and the stack effect
is reduced. If the air is drawn from outside the house (13), the air pressure
in the lower areas of
the house (13) is increased, thus the air pressures in the house (13) are more
closely equalized
and the stack effect is reduced.
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The method according to the present invention provides for an auxiliary air
supply located inside
the house and/or outside the house to reduce the effects of the air pressure
variation, i.e. the stack
effect, and prevent back drafting, The method broadly comprises the steps of
1) affixing an
auxiliary air supply means (14) to an existing exhaust stack (6) of an
existing combustion device
located in an area of lower relative air pressure (below the neutral pressure
plane), (2) supplying
the auxiliary air supply means with air from an aperture (15) located in an
area of higher relative
air pressure (above the neutral pressure plane). Since air located in a higher
relative air pressure
area will flow freely to an area of lower relative air pressure this will
create an escape for the air
in the higher relative air pressure are and balance the two different air
pressures.
The method according to the present invention may further comprise the step of
controlling the
air flow through the auxiliary air supply by way of a damping means (16). This
ensures that the
air can only flow out of the house in one direction and not into the house.
An embodiment of the present invention was installed and tested in a house.
Two 6" aluminum
round ducts were connected to the exhaust pipes of a furnace and a water
heater tank and sealed
with aluminum duct tape, the two aluminum round ducts are connected together
with a 6"
aluminum T round duct, the duct was then ran through the house to the uppers
levels of the house
and into the attic. In general, the attic of a house is vented to the outside
and thus will
have the same air pressure. The duct was held in place in the ceiling with a
duct thimble.
Temperature tests were conducted at various spots on the duct. The outside air
temperature was
at -15 C. At a point 18" below the ceiling the temperature was measured to be -
12 C and at the
point where the auxiliary air supply is affixed to the exhaust pipe the
temperature was measure
to be -0.2 C. This means that the cold air flowing down the auxiliary air
supply is warmed up
approximately 15 C before it reached the connection point. This shows that air
is indeed being
drawn down into the lower air pressure areas and is equalizing the air
pressure in the house as
a result of the fresh air originating from the attic.
A kit is also provided for performing the method as described herein. The kit
may broadly
comprise adequate duct to reach from an existing exhaust stack to a desired
area of higher air
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pressure, duct tape for sealing the duct, duct insulation, flexible duct, a
duct thimble, a vent or
a directional vent (17, and a damper.
Optionally the air that is flowing from the area of higher relative air
pressure to the area of lower
relative air pressure may be outputted into the area of lower relative air
pressure. Optionally the
air that is flowing from the area of higher relative air pressure to the area
of lower relative air
pressure may be vented outside the house via the exhaust stack (6), the flue
or chimney (10) or
outside the house directly.
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