Heating Info From Warmair.net
Replacement Tips
Btu
Before you replace that burned out furnace or boiler with a new one, make
sure it is the right size to begin with. Don’t take for granted
that the original installer didn’t make a mistake. Especially
where forced air furnaces are involved, the sizing of the ductwork
is critical to the heating capacity of the entire system.
A 150,000 Btu furnace feeding ductwork sized for 1000 cfm does not deliver
150,000 Btu to the dwelling. Most likely, the burner kicks out
on high limit due to over heating. Which is what it should do
if there is not enough air flow. In such a case, this furnace
has never produced at full capacity, and its longevity was shortened
by the steady over heated condition.
All furnace manufacturers match Btu and cfm output. If the ductwork cannot
support the cfm requirement, the furnace will not perform to its
potential. When replacing a burned out furnace, match the Btu
to the ductwork as best you can.
Breech
Venting of gas and oil burning sytems
The smoke pipe, or connector from the combustion chamber to the chimney,
must run uphill. Before you purchase a replacement boiler of furnace,
make sure the breech on the new unit will be lower than the opening
in the chimney.
For warm air furnaces, it is also necessary to match the style of furnace with
the ductwork. Furnaces are produced in different configurations
for different applications. There are counter flow models with a
downward flow, low-boy models and high-boy models with an upward
flow, and horizontal models with a sideways flow. Some models also
come in front or rear flue arrangements which must also be matched.
Make sure you equal or improve the venting of any replaced unit.
Blower
In response to the increased popularity of central cooling in
the last twenty years, many furnace manufacturers raised the air
flow capacity of their warm air furnaces by converting from belt
driven blowers to variable speed direct drive blowers. This change
not only increased the air flow capacity of the system, but the
noise factor as well. These blower motors run at higher speeds
than the old lumbering belt driven versions and can therefore
produce more air noise.
Extra precautions, such as canvas or flexible connecters, are
needed when installing a direct drive blower in place of a belt
drive.
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