Thermo Pride CLQS1-050T36N Installation And Operation Manual page 39

All installations and services must be performed by qualified service personnel.
5. The duct system shall be sized for the maximum CFM requirement of the installation whether it is for
heating or cooling. Two common rules for heating and cooling follow:
A. COOLING: 400 CFM (1200 BTU's) per ton of cooling is typically required.
B. HEATING: 14 CFM of heating per 1,000 BTU's of furnace output based on a nominal temperature
rise.
EXAMPLE:
Heating output of a furnace is 100,000 BTU: 100 x 14 CFM = 1400 CFM
Air conditioning installed is 4 tons: 4 x 400 CFM = 1600 CFM
NOTE: The duct system must be sized for the larger CFM requirement for cooling. If only 3 tons of
cooling were installed: 3 x 400 CFM = 1200 CFM. The duct would then have to be sized for the 1400
CFM heating requirement.
All trunk lines, take-offs, registers and grill-free areas must be figured when determining the air handling
capacity of a duct system. Use a supplier's catalog for proper sizing of outlet and return air registers to
insure that the register will meet the CFM requirements of the run to which it is connected.
The speed of the blower motor may have to be changed to obtain the proper 45°F to 75°F temperature
rise for heating when an air conditioning coil is installed. This depends on the static resistance of an
individual duct system and the size of the air conditioner.
L. FILTERS
It is necessary to cut the return air opening in the casing depending upon the needs of the specific
installation. It is possible to cut the return air opening in the left, right, or bottom of the cabinet.
NOTICE: If your furnace will require air delivery above 1800 CFM it is advisable that both sides, or a
combination of 1 side and the bottom, be used.
This furnace has been factory supplied with a high quality re-usable filter rated for air velocities up to 600
ft/min. An optional Thermo Pride filter rack assembly (part no. AOPS7547 for -050, -075 & -100 and
AOPS7375 for -125)
is available which is sized for the filter provided. See Figure 12.
This filter should be inspected monthly. When dirty, the filter must be cleaned or replaced, if necessary,
to assure proper furnace operation. Follow the cleaning, removal and replacement procedure below.
NOTICE: If the furnace is installed in a home or structure being remodeled, dust levels may be much
higher than normal. The filter must be inspected daily and cleaned as needed until dusty conditions have
been eliminated.
: This furnace is not to be used for temporary heating of buildings or structures under
construction.
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