Thermo Products MDA1-125N, MDA1-50N, MHA1-75N, MHA1-100N, MHA1-50N, MHA1-125N, MDA1-75N Fpm, Formula

All installations and services must be performed by qualified service personnel.

Table 2: Minimum Filter Area Required (Sq. in.)

	Maximum		Furnace Model
Filter Type	Rate of
		MHA1-50	MHA1-75	MHA1-100	MHA1-125
	Velocity
	(FPM)	MDA1-50	MDA1-75	MDA1-100	MDA1-125
*THERMO
PRODUCTS
SUPPLIED	600	172	254	328	402
PERMANENT
FILTER
STANDARD
PERMANENT	500	208	304	394	484
FILTER
DISPOSABLE
TYPE	300	344	506	656	804
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 500

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.

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