Filter
Top Products
All installations and services must be performed by qualified service personnel.
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3. USE OF NON-THERMO PRIDE FILTER RETENTION MEANS
If a method other than the Thermo Pride filter rack is selected for retention of the filter and/or use of a
different filter type is desired, see Table 3 for minimum size guidelines for selecting a filter system for the
CHX1 or CDX1 furnaces.
MINIMUM FILTER AREA REQUIRED (LENGTH X WIDTH, SQ. IN.)
TABLE 3
FILTER TYPE MAXIMUM
RATE
AIR VELOCITY
Required CFM / (Filter Velocity Rating x 144) = min. filter
(in
2
)
FURNACE MODEL
CHX1,CDX1-75 CHX1,CDX1-100 CHX1,CDX1-125
*THERMO
PRODUCTS
SUPPLIED
PERMANENT FILTER
600 FT./MIN. 254 IN.
2*
328 IN.
2*
402 IN.
2*
STANDARD
PERMANENT FILTER
500 FT./MIN. 304 IN.
2
394 IN.
2
484 IN.
2
DISPOSABLE TYPE
FILTER
300 FT./MIN. 506 IN.
2
656 IN.
2
804 IN.
2
* The Thermo Products supplied filter can be cut to size to fit other filter retention systems as long as the
minimum size requirement is met. NOTICE: Any internal stiffeners used in the filter must not be removed,
although they can be cut to size as needed.
NOTICE:
The filter areas in table 3 are the minimum areas required based on the CFM generated by the
furnace for standard heating speeds only. The following formula can be used to determine the minimum
filter area required for cooling if the unit is equipped with cooling. This value should then be compared to
the value shown in table 3 and the larger of the two should then be used for determining the minimum filter
area required for that installation.
FORMULA:
(tons of cooling) x (400 CFM per ton) (144 square inches per foot)
= filter area sq.inches
(max. air velocity of filter from table 3 for the filter type) = length x width of
filter in inches
EXAMPLE: If you had a CHX1-100 furnace and 4 tons of cooling and a standard permanent filter.
4 tons x 400 CFM x 144
= 460 square inches for cooling
500
For heating a CHX1-100 needs 394 square inches of filter. The filter system must be designed for the
larger CFM requirement determined for cooling of 460 square inches. A filter would have to be sized so
that the area (length X width) was at least
460 sq. in.
L. WIRING
All wiring shall be performed by a qualified electrician or service person. The wiring must comply with local
codes, the instructions in this manual, and in the absence of codes with the National Electrical Code
(ANSI/NFPA-70 or latest edition).
1. The following items are guidelines to complete the wiring portion of the installations.