Thermo Pride Gas/Propane Furnace Premiere Series 2-Stage CHX3 User Manual
Page 35
All installations and services must be performed by qualified service personnel.
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K. FILTERS
1. CHX3 MODELS: HIGHBOYS
It is necessary to cut the return air opening in the bottom or side casing depending upon the needs of the
specific installation.
NOTICE: If your CHX3 will require air delivery above 1800 CFM, it is advisable that both sides, a
combination of 1 side and the bottom, or the bottom only be used for return air. (If a return is cut in the
bottom, it should be as large as the return opening in the equivalent CDX3 model. (See specification sheet
in beginning of this manual).
This CHX3 furnace has been factory supplied with a high quality re-usable filter rated for air velocities up
to 600 ft/min. An optional Thermo Products filter rack assembly (part no. AOPS7547 for CHX3-75 thru 100
and AOPS7375 for CHX3-125) is available which is sized for the filter provided.
If an optional Thermo Pride filter rack AOPS7547 (figure 19) is used with the furnace, it will serve as a
template to scribe a mark for the return air opening on the casing. Place the filter rack on the casing one
inch up from the bottom of the furnace and centered from side to side. Place the securing flange against
the casing for locating the return air opening.
Figure 19
PLEASE NOTE: While scribing the return air opening, the filter rack can be held into position by tape or
similar means.
Position the open end of the filter rack so that it is accessible for filter replacement. Once the filter rack is
positioned correctly, scribe a line along the inside of the securing flange of the filter rack on three of the
sides. To scribe a line on the fourth side, on the open end, use the open end support for a guide.
Remove the filter rack and cut the return air opening in the casing. Now the filter rack can be permanently
attached to the furnace with screws or pop-rivets along the securing flange.
Connect the return plenum to the filter rack and slide the filter into place.
2. CDX3 MODELS: COUNTERFLOWS
This CDX3 furnace has been factory supplied with two high quality reusable filters rated at 600 ft/min.
These filters are designed to be mounted on the return air plenum opening on the top of the furnace in the
double “vee” style rack provided (see Figure 20). If feasible, it is recommended that slits be cut in the
return front to allow for easier access of the filters.