Do the phrases "This room is always
too cold" or "My bathroom fan doesn't
do anything" ring a bell? Whenever a
homeowner complains about the performance
of some heating or ventilating
equipment, it's handy to have a
flow-measuring device available to
check out the complaint.
The Research Division of Canada
Mortgage and Housing Corporation
(CMHC) has been testing ventilation
system performance for years, sometimes
with specially built equipment. While
this equipment can accurately measure
flows, it's too bulky, expensive, and fragile
to be of real use in day-to-day inspections.
So an inexpensive alternative was
developed — the calibrated garbage bag.
To make the bag tester, open a wire
coat hanger up until you have a rough
rectangle. Now tape the