U.S. patent application number 11/403940 was filed with the patent office on 2006-08-24 for pressurizing buildings to improve drying.
Invention is credited to Claude Bourgault, Larry Dancey.
Application Number | 20060189270 11/403940 |
Document ID | / |
Family ID | 36913385 |
Filed Date | 2006-08-24 |
United States Patent
Application |
20060189270 |
Kind Code |
A1 |
Bourgault; Claude ; et
al. |
August 24, 2006 |
Pressurizing buildings to improve drying
Abstract
A method of drying a building includes closing all openings in
the building such that air movement out of the building is
restricted, drawing air from outside the building, heating the
outside air, and directing a stream of the heated outside air into
the building through an input duct. The building air pressure of
air inside the building is measured and compared to a desired
building air pressure that is less than the input pressure. Where
the measured building air pressure is greater than the desired
building air pressure, a substantially controlled flow of air is
allowed to exit the building at an exhaust location and the flow of
air from the building is controlled to maintain the building air
pressure at the desired air pressure.
Inventors: |
Bourgault; Claude; (St.
Brieux, CA) ; Dancey; Larry; (Melfort, CA) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Family ID: |
36913385 |
Appl. No.: |
11/403940 |
Filed: |
April 14, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10751455 |
Jan 6, 2004 |
|
|
|
11403940 |
Apr 14, 2006 |
|
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Current U.S.
Class: |
454/235 |
Current CPC
Class: |
E04B 1/7015 20130101;
F24F 2110/40 20180101; F24F 7/007 20130101; F24F 2011/0004
20130101; F24F 2221/34 20130101 |
Class at
Publication: |
454/235 |
International
Class: |
F24F 7/06 20060101
F24F007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2006 |
CA |
2,537,032 |
Claims
1. A method of drying an interior of a building, the method
comprising: closing substantially all openings in the building such
that air movement out of the building is restricted; drawing
outside air from outside the building, heating the outside air, and
directing a stream of the heated outside air into the building
through at least one input duct at an input pressure; measuring a
building air pressure of air inside the building; comparing the
measured building air pressure to a desired building air pressure
that is less than the input pressure; and where the measured
building air pressure is greater than the desired building air
pressure, allowing a substantially controlled flow of air to exit
the building at an exhaust location and controlling the flow of air
from the building to maintain the building air pressure
substantially at the desired air pressure.
2. The method of claim 1 further comprising, where the measured
building air pressure is less than the desired building air
pressure, drawing an increased volume of outside air into the
building.
3. The method of claim 2 further comprising increasing the amount
of air drawn into the building until the desired building air
pressure is substantially maintained.
4. The method of claim 1 comprising configuring an input location
of the at least one input duct and the exhaust location such that
an air flow is created from the input location through a desired
area of the building to the exhaust location.
5. The method of claim 4 comprising allowing a substantially
controlled flow of air to exit the building at first and second
exhaust locations configured such that a first air flow is created
from the input location through a first desired area of the
building to the first exhaust location and such that a second air
flow is created from the input location through a second desired
area of the building to the second exhaust location.
6. The method of claim 1 comprising directing a stream of the
heated outside air into the building through a plurality of input
ducts located at a plurality of input locations.
7. The method of claim 1 wherein the desired building air pressure
is between 0.25'' WC and 0.70'' WC compared to an ambient pressure
of the outside air.
8. The method of claim 1 wherein the outside air is heated with a
heating element, and wherein the amount of heat supplied to the air
stream is adjusted.
Description
[0001] This application is a continuation-in-part (CIP) of U.S.
patent application Ser. No. 10/751,455 "METHOD AND APPARATUS FOR
CONTROLLING HUMIDITY AND MOLD", filed Jan. 6, 2004, the disclosure
of which is hereby incorporated herein by reference.
[0002] This invention is in the field of drying building interiors
that have excessive moisture accumulated therein, and in particular
with drying building interiors with a pressurized flow of dry
air.
BACKGROUND
[0003] It is well known that excessive moisture in buildings causes
considerable problems. Drywall and flooring absorb moisture and are
readily damaged if the excessive moisture condition persists for
any length of time. Interior elements such as insulation, studs,
and joists can eventually be affected as well. Furthermore, mold
begins to form on the damp building materials, and can remain in
the structure even after it has dried, causing breathing problems
for persons occupying the building.
[0004] At the extreme, such excessive moisture conditions are
exemplified by a flooded building. U.S. Pat. No. 6,457,258 to
Cressy et al., "Drying Assembly and Method of Drying for a Flooded
Enclosed Space", discloses an apparatus for drying flooded
buildings that overcomes problems in the prior art. Such prior art
is said to require stripping wall and floor coverings and using
portable dryers to circulate air to dry out the exposed floor
boards, joists and studs. The methods were slow and allowed mold to
form on the interior framing, which could then go unnoticed and be
covered up and then later present a health hazard to occupants.
[0005] The solution proposed by Cressy is to introduce very hot and
dry air into the building, indicated as being at 125.degree. F. and
5% relative humidity, in order to dry the building very quickly to
prevent mold growth and allow an early return to occupants. In the
apparatus of Cressy et al., outside air is heated by a furnace and
the dry heated air is blown through a dry air duct into a location
in the building. An input end of an exhaust duct is positioned in
another part of the building such that the dry air moves out of the
dry air duct, picks up moisture from the building and then moves
into the input end of the exhaust vent and out of the building. In
Cressy the warmer exhaust air is directed through a heat exchanger
such that heat therefrom is transferred to the cooler outside air
prior to heating by the furnace, thereby increasing the efficiency
of the system.
[0006] Prior art systems for drying flooded buildings also include
desiccant dehumidifiers that use a desiccant material with a high
affinity to water to absorb water from the air, and refrigerant
dehumidifiers that condense water out of the air by cooling it. In
both of these systems, the water must be disposed of in some
manner. The water absorbed by the desiccant material is removed by
subsequently drying the material. The water condensed by the
refrigerant system is collected in a reservoir that must be emptied
from time to time or piped to a disposal area. Such systems are
relatively costly to manufacture and operate, and are relatively
slow to remove moisture from the subject building.
[0007] U.S. Pat. No. 6,647,639 to Storrer, "Moisture Removal
System", addresses the problem of extracting water from interior
portions of a structure such as inside walls and from hardwood
floors. Storrer discloses using a blower to blow (or draw) dry air
through a hose and manifolds that can be directed through injectors
into the interior of walls.
[0008] Similarly, U.S. Pat. Nos. 5,960,556 to Jansen, "Method for
Drying Sheathing in Structures", is directed to drying walls with
warm, low humidity air. U.S. Pat. Nos. 5,893,216 to Smith et al.,
U.S. Pat. No. 5,555,643 to Guasch, and U.S. Pat. No. 5,408,759 to
Bass disclose systems for drying walls by directing pressurized air
into the inside of the wall.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a system
for drying buildings that overcomes problems in the prior art.
[0010] Co-pending United States Patent Application 2005/0145109 of
the present inventors Dancy et al. discloses a controlled system
for maintaining a desired humidity level in buildings and for
drying buildings. Portable heat exchanger units comprise a
temperature adjusting element, illustrated for example as
comprising a fluid coil and a fan drawing air from an inlet through
the coil and out an outlet. The coil is connected by conduits to a
fluid heater or fluid cooler such that the air passing through the
coil can be either heated or cooled. By drawing in outside air and
heating it, the relative humidity of the air is reduced, and the
drier air is directed into the building. A vent is provided,
typically somewhere opposite the intake, so that the drier air
moves through the building and picks up moisture from building and
carries it out through the vents.
[0011] The relative humidity of the air is an indicator of how much
water the air is holding, and thus how much more water it can hold.
The amount of water air can hold increases with the temperature of
the air, and the relative humidity thus decreases as the
temperature increases. By way of illustration, in a closed room
with standing water on the floor, the relative humidity of the air
in the room would approach 100% (i.e. the air would become
saturated with water) and so no more water would evaporate off the
floor. Raising the air temp 10.degree. C. will reduce the relative
humidity by 50% to a 50% relative humidity, resulting in a moisture
gradient between the water and the air, and thus more water will
evaporate off the floor and the relative humidity will again rise
to 100%, provided no air moves in or out of the room.
[0012] By bringing in a dry air stream at a first location in the
room and opening an exhaust vent, such as a window, door, at a
second location in the room, air entering at the first location
pushes the air in the room toward the second location and out the
vent. As the dry air moves through the room it picks up moisture
and takes the moisture out through the vent. Over time the water
will eventually evaporate and be carried out of the room.
[0013] A heat controller can be operated to supply heat at the
proper rate to achieve a desired relative humidity in the air
stream, and thus in the enclosed space. On a wet day for example if
the outside air has a relative humidity of 100%, raising the
temperature of the outside air by 20.degree. C. will reduce the
relative humidity of the air stream to 25%. Alternatively raising
the temperature of the outside air by 40.degree. C. will reduce the
relative humidity of the air stream to about 6% and provide fast
drying in a flooded building, where damage to sensitive materials
is not an issue.
[0014] The present invention provides, in a first embodiment, a
method of drying a building. The method comprises closing
substantially all openings in the building such that air movement
out of the building is restricted; drawing air from outside the
building, heating the outside air, and directing a stream of the
heated outside air into the building through at least one input
duct at an input pressure; measuring a building air pressure of air
inside the building; comparing the measured building air pressure
to a desired building air pressure that is less than the input
pressure; and where the measured building air pressure is greater
than the desired building air pressure, allowing a substantially
controlled flow of air to exit the building at an exhaust location
and controlling the flow of air from the building to maintain the
building air pressure substantially at the desired air
pressure.
[0015] A significant proportion of buildings that require drying
due to floods or mishaps will be fairly poorly sealed against the
elements. For example in many areas, especially those in warmer
climates, vapor barriers are not commonly installed. Thus it is
possible to pressurize the interior of these buildings with heated
dry air using a fan similar to a furnace fan, or like available
fan, to a level of about 0.2 to 0.5 water column inches (''WC) and
force air through the walls and ceilings of the building. The
method also provides improved drying of buildings that are better
sealed against air movement.
[0016] For example, a portable heat exchanger unit comprising a
fluid coil connected to a fluid heater and a fan drawing air from
an inlet through the coil and out an outlet can be used to draw in
outside air, heat it to reduce the relative humidity thereof, and
direct a stream of the dry heated outside air into the building
through an input duct at an input pressure of about 0.6-0.7'' WC.
With all openings in the building closed, such as windows, doors,
vents, or the like, air movement out of the building is restricted
to the extent possible. When the air stream is directed into the
closed building, the building air pressure inside the building will
rise. As the building air pressure rises, air inside the building
will seek to flow to the lower pressure ambient air outside the
building, and will thus flow out through cracks and the like in the
walls and ceiling. The dry air picks up moisture from inside the
building, and from inside wall areas to a certain extent as well,
and carries it out as it exits the building.
[0017] The input pressure developed by the fan is a pressure
differential between the air exiting the input duct and the ambient
outside air. Where the doors and windows of the building are open a
very low pressure will develop in most buildings, depending on the
number and location of the doors and windows. The fan will thus be
drawing air in and blowing it out against negligible pressure. The
volume of air in the air stream for any given fan at those
conditions will be known, and the fluid heater can be adjusted to
provide the desired temperature rise to that volume of air
flow.
[0018] When drying a building by directing a heated and dried air
stream through the building the amount of time air remains in the
building will depend on the volume of the interior of the building.
For example where the air stream has a volume of 5000 cubic feet of
air entering the building every minute (cfm), and the building has
a volume of 25,000 cubic feet, the air inside the building will
essentially change every five minutes. At this rate of air
movement, the amount of moisture carried out by the air stream will
depend on the degree of moisture in the building, and the relative
humidity of the entering air stream. The lower the relative
humidity of the air stream, the higher the moisture gradient
between the air inside the building and the wet building surfaces,
and the faster moisture will be absorbed by the air. When the air
is in the building, it absorbs moisture and the relative humidity
thereof rises. The longer the air remains in the building then, the
more moisture it will absorb, and thus the longer the air remains
in the building, the lower the rate of moisture absorption and
drying.
[0019] Basically then, for any given relative humidity of the air
stream, the faster the air moves through the building the faster
the building will be dried. The operator thus is typically
attempting to push the air through the building as quickly as
possible, and thus opens such windows and doors as are available in
order to reduce the pressure inside the building to a minimum and
maximize the volume of the air stream flowing through the
building.
[0020] With the method of the present invention however, the
operator will determine that at a building air pressure of 0.25''
WC, where the inside pressure will be such that the air will try to
force its way through wall openings, the fan will only create an
air stream volume of perhaps 3500 cfm instead of the 5000 cfm
available where building air pressure is negligible. The operator
then will start the fan with all building openings closed. As the
air stream enters the building, the building air pressure will
rise, and the operator will monitor the building air pressure with
a manometer or the like, with a view to attaining the desired
building air pressure of 0.25'' WC, and input air volume of 3500
cfm.
[0021] With the doors, windows, and whatever other openings might
be present closed, the building air pressure will rise to an
equilibrium point where the amount of air in the air stream will
equal the amount of air leaking out of the building through door
seals, window seals, cracks and the like. Where the building is
poorly sealed, the building air pressure at this equilibrium point
may be less than the desired building air pressure of 0.25'' WC. In
this situation the operator may choose to simply allow the air to
flow through the building at whatever the building air pressure is
at equilibrium, and then adjust the heat to raise the temp of the
air stream to the desired level. Where obvious large air leakage is
occurring the operator may attempt to seal these leaks.
[0022] Alternatively the operator may increase the volume of air
flowing into the building by adding a second fan to boost air flow
through the coil, or by adding a second portable heat exchanger
unit, or by like means such that the building air pressure rises
above the desired pressure of 0.25'' WC.
[0023] Where the building is relatively well sealed, the building
air pressure will rise, and could approach the input pressure
developed by the fan. At that state very little air would be moving
into the building.
[0024] In any event, when the building air pressure exceeds the
desired pressure of, in the present example, 0.25'' WC, the
operator allows a substantially controlled flow of air to exit the
building at an exhaust location and controls the flow of air from
the building to maintain the desired air pressure. Typically the
operator will accomplish this end by partially opening a door or
window in the building at a location opposite the input location
where the air stream is entering the building.
[0025] The operator will adjust the heat supplied by the fluid
heater to a setting where the fluid coil will raise the temperature
of the air stream by the desired amount.
[0026] The invention further provides the opportunity to control
the direction of the flow of air through the building by
positioning the exhaust location. For example where one room or
area is wetter than the rest of the building the exhaust location
can be positioned such that the wetter area is between the input
location and the exhaust location. Air flow will be greatest
between the input and output location as the air stream seeks to
exit the building to the lower pressure outside. Interior fans will
typically be provided at locations throughout the building to
agitate the air and circulate same along the walls to improve
drying, however by moving the air stream directly through the
wetter areas of the building, drying times will typically be
reduced. Where there are two wetter areas in a building, two
exhaust locations could be provided to split the air flow and
direct a portion of the air flow through each wetter area.
Similarly where a plurality of air streams are available, the input
locations could be positioned to direct the air flow as desired as
well.
[0027] It is also contemplated that pressurizing the building
interior will improve the circulation of air through the building
by pushing air into all corners and like areas that are somewhat
removed from the main air flow path. It is also contemplated that
the pressurized air will also push against the wet surfaces
improving moisture transfer from the surfaces to the air.
DESCRIPTION OF THE DRAWINGS
[0028] While the invention is claimed in the concluding portions
hereof, preferred embodiments are provided in the accompanying
detailed description which may be best understood in conjunction
with the accompanying diagrams where like parts in each of the
several diagrams are labeled with like numbers, and where:
[0029] FIG. 1 is a schematic top view of a building interior
showing all openings in the building closed such that the building
air pressure rises and at least some air exits the building
interior through the building structure;
[0030] FIG. 2 is a schematic top view of the building interior of
FIG. 1 showing a window opened to allow a controlled flow of air to
exit the building interior;
[0031] FIG. 3 is a schematic top view of the building interior of
FIG. 1 showing a window and a door opened to allow a controlled
flow of air to exit the building interior through two locations;
and
[0032] FIG. 4 is a schematic top view of the building interior of
FIG. 1 showing a window and a door opened to allow a controlled
flow of air to exit the building interior through two locations,
and showing an increased amount of air being drawn into the
building interior.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS:
[0033] FIGS. 1-4 schematically illustrate a method of drying an
interior 1 of a building 3. The method comprises closing
substantially all openings in the building, such as windows 5 and
doors 7, such that air movement out of the building is restricted,
as illustrated in FIG. 1. Outside air is drawn from outside the
building 1 and heated, and a stream 9 of the heated outside air is
directed into the building 1 through an input duct 11 at an input
pressure.
[0034] While it is contemplated that other apparatuses could be
used, in the illustrated embodiment, the air stream 9 is
conveniently provided by a portable heat exchanger unit 13
comprising a fan and a coil heating element. The air is heated by
hot fluid circulating through the coil from a boiler 15, or like
fluid heater. As the air stream is forced into the building through
the input duct 17 at the input pressure developed by the fan, the
air pressure in the building interior 1 rises, since the windows 5
and doors 7 a have been closed. The input duct 17 is substantially
sealed to the building 3 to prevent escape of air. Using a
manometer or like instrument, the building air pressure of the air
inside the building 3 is measured, and compared to a desired
building air pressure that is less than the input pressure.
Typically the input pressure will be about 0.6-0.7'' WC compared to
the air pressure outside the building 3, and the desired building
air pressure in the interior 1 of the building 3 will be about
0.25-0.40'' WC, creating a pressure gradient between the building
interior 1 and the air outside of the building 3 such that air
inside the building will seek to pass through the structure to the
lower pressure outside the building.
[0035] At least some air will flow through cracks or the like in
the walls and roof, especially in buildings with no vapor barrier,
as indicated by arrows 9A showing portions of the air stream 9
passing through the walls of the building 3. For example, air will
enter a crack in the interior wall surface, and flow along the
inside of the wall until it comes to a crack or the like in the
outside wall surface through which the air will flow to the lower
pressure outside. In this way, some air circulation will be
developed inside the walls that will help to dry the inside of the
wall.
[0036] Typically in a relatively sound building after the fan has
been running for a period of time and equilibrium has been reached,
the measured building air pressure will be greater than the desired
building air pressure. The operator will then select an exhaust
location, typically an available window 5 or door 7, although an
exhaust could be provided of any kind, and a substantially
controlled flow of air will be allowed to exit the building at the
exhaust location to maintain the desired air pressure. Typically
the exhaust will be opened a small amount, and when equilibrium is
reached the building air pressure will be measured again. If it is
still above the desired pressure, the exhaust will be opened
further, and this process will be repeated until the desired
building air pressure is attained, at which time the exhaust will
be fixed in place, the amount of heat supplied to the air stream
will be adjusted to provide the desired temperature rise, and
drying will proceed. FIG. 2 illustrates the window 5A being used to
provide the exhaust.
[0037] The method of the invention also provides for directing the
flow of the air stream 9 through the building such that the air
flow is increased through wetter areas or other desired areas of
the building interior 1 by configuring the input location of the
input duct 17 and the exhaust location such that an air flow is
created from the input location through a desired area of the
building to the exhaust location. For example FIG. 2 illustrates a
desirable configuration of the input duct 17 and exhaust location
at window 5A where it is desired to increase airflow through the
room 19 in the building interior 1, such as where the room 19 may
be wetter than the rest of the building interior 3. Thus a portion
of the air stream 9A will continue to exit through the structure,
and a portion 9B will exit through the window 5A. While circulation
fans, not shown, will typically be used in the building interior 1
to circulate air in the building against the walls, air flow
through the room 19 will be greater than through the balance of the
building interior 1.
[0038] FIG. 3 illustrates a configuration where a substantially
controlled flow of air is allowed to exit the building interior 1
at two exhaust locations, the window 5A and door 7A, such that in
addition to the air flow 9A through the structure, a first air flow
9B is created from the input duct 17 through a first desired area
of the building, the room 19, to the first exhaust location at
window 5A, and a second air flow 9C is created from the input duct
17 through a second desired area 21 of the building to the second
exhaust location at door 7A. With the door 7A opened, the window 5A
will be closed somewhat compared to its position in FIG. 2, since
it will be desired to maintain about the same area of opening that
was provided by the window 5A alone in FIG. 2 using the window 5A
and the door 7A in FIG. 3.
[0039] Where the building interior 3 is about equally wet
throughout, the configuration of FIG. 3 allows the room 19 to
experience sufficient air flow for drying that may not be available
without an exhaust location in the room 19.
[0040] In some less well sealed buildings, such as older or damaged
buildings, the air stream provided by a single portable heat
exchanger unit may not be sufficient to raise the building air
pressure to the desired level because is leaking out as fast as it
is coming in. It may be that the operator will choose to simply let
the air flow out of the building through the structure, or he could
draw an increased volume of outside air into the building interior
1 by adding a second portable heat exchanger unit 13A as
illustrated in FIG. 4 directing a second air stream 9' into the
building interior through a second input duct 17A. The steps set
out above would typically be followed to maintain the desired
building air pressure.
[0041] The foregoing is considered as illustrative only of the
principles of the invention. Further, since numerous changes and
modifications will readily occur to those skilled in the art, it is
not desired to limit the invention to the exact construction and
operation shown and described, and accordingly, all such suitable
changes or modifications in structure or operation which may be
resorted to are intended to fall within the scope of the claimed
invention.
* * * * *