How Safe Do You Think your Home
is?
Maybe it's time to think again?
Depressurization a Serious Safety Cconcern
Winnipeg - Brian Baker, President of Custom
Vac Limited, a local Heating, Ventilation and Air Conditioning (HVAC) contractor says, "One area that contracting firms are finding
very challenging is the issue of home depressurization." The latest
in-home research conducted in Manitoba has proven the levels of
depressurization occurring in both, new homes and older homes
is potentially a serious safety issue that remains unresolved.
In the past technicians
were taught that they need only concern themselves with energy
efficient new homes as it was believed that they had a greater
potential for depressurization problems. "Not true", said Baker.
Research conducted over the past 3 years has proven that any home
of any age and style can have and experience serious depressurization
conditions.
What is Depressurization?
Depressurization is a condition that is created when air within
the home is exhausted by natural or mechanical means. As air within
the home is being removed, pressure levels within the home are
lowered. This lowering of air pressure within the home increases
air leakage into the home around doors, windows and other cracks
in the building envelope. With the building pressure reduced,
the least restrictive way in which to bring air back into the
home is via the chimney and that is typically what happens, air
is drawn back down the chimney allowing the products of combustion
to enter the home.
"This can create a very hazardous condition that has the potential
to cause serious injury and even death in cases where carbon monoxide
(co) is being produced", said Baker. Many homes have a 5" or 6"
fresh air duct connected to the return air of the furnace and
a 5" or 6" combustion air duct supplied to the furnace area. This
may not be enough! In some homes just by operating the dryer the
home can exceed the -5pascals depressurization limit allowed by
the code.
Current Standards Fall Short
The research in Manitoba has shown that the present codes, standards,
installations, and inspection methods have fallen short. Even
though installations follow the codes and standards, and are inspected
by the authorities, at present this does not guarantee that a
home will not experience a serious depressurization condition.
The reason why says Baker is, "there is no requirement or enforcement
to conduct a depressurization test when servicing, maintaining
or installing or replacing a piece of equipment." Some homes in
Manitoba have been shown to have depressurization levels well
in excess of -20 Pascal's (pa) [-5 pa. = 0.02" water column (wc)]
If you have exhaust devices, central vacuum systems, bathroom
fans, dryers, kitchen range fans or any other device(s) that exhaust
air from the home there is a greater potential for a problem.
Depressurization can also be a problem in homes that have high,
large, or multiple chimneys. The reason is that these chimneys
create high negative draft conditions that will pull more air
from within the home, which again has been proven in actual tests
to be a serious problem.
Get Tested and Be Certain
"Testing can be done
to determine the level of depressurization and once determined
remedial measures if required can be proposed", said Baker. His
firm has been working with an independent consultant since this
type of research began in Manitoba, and is proud to say that his
company is one of a small handful of concerned Contractors leading
the way for change in this area.
"There is no way for any technician to know for certain whether
or not there is a depressurization problem with a home when performing
a service for the homeowner by simply looking at the home. The
only way to determine the depressurization limit of a home is
to conduct a test, said Baker".
Homeowners tend to think that their homes are not airtight and
therefore are not a problem. "This is just not the case and the
actual in-home research proves that", said Baker. Just like we
need to educate homeowners about the signs and dangers of carbon
monoxide we need to spend time to educate them about depressurization
and how the two are inter-related. CO and depressurization are
similar in that you cannot detect or identify a problem without
the proper testing equipment. With over 600 homes tested in Manitoba,
25% or 1 out of 5 homes tested, exceeded the -5 pa. limit set
out in the codes, a real eye opener for all those homeowners who
think their homes are leaky, said Baker.
In Summary
"Homeowners should have a depressurization test conducted to identify
any potential safety issues that could affect occupants within
the home. The test needs to be performed by trained and qualified
persons. In addition, Brian suggested, that homeowners planning
to install an exhaust device or retrofit their homes building
envelope regardless of how minor it may seem, should consult with
a Heating Refrigerating and Air Conditioning Institute of Canada
(HRAI) certified residential mechanical ventilation designer and
installer, they have been trained to Nationally recognized standards
and undergo training updates to remain current with the changes
as they occur.
