Thermo Pride MHA1-50N Installation And Service Manual page 15

All installations and services must be performed by qualified service personnel.
Filter Type
*THERMO
PRODUCTS
SUPPLIED
PERMANENT
FILTER
STANDARD
PERMANENT
FILTER
DISPOSABLE
TYPE
FILTER
* 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: The filter areas in Table 2 are the minimum areas required based on
the flowrate 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 2 and the larger of the two should then be used for
determining the minimum filter area required for that installation.
FORMULA:
(tons of cooling)(400 CFM per ton)(144 sq. in. per foot) = filter area sq. inches
(max. air velocity of filter from table 5 for the filter type)
EXAMPLE: If you had an MHA1/MDA1-100 furnace and 4 tons of cooling and a
standard reusable filter.
4 tons x 400 CFM x 144 = 460 square inches for cooling
For heating an MHA/MDA-100 needs 328 square inches of standard reusable
filter. The filter system must be designed for the larger flow 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.
Table 2: Minimum Filter Area Required (Sq. in.)
Maximum
Rate of
MHA1-50
Velocity
MDA1-50
(FPM)
600
500
300
500
Furnace Model
MHA1-75
MDA1-75
172 254
208 304
344 506
11
MHA1-100 MHA1-125
MDA1-100 MDA1-125
328 402
394 484
656 804