Thermo Pride Gas/Propane Furnace Premiere Series 2-Stage CHX3 - Manual (Page 37)

All installations and services must be performed by qualified service personnel.
31
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 CHX3-100 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 CHX3-100 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.
a. A separate power supply circuit with over current protection and a disconnect switch must be
provided. The minimum fuse or circuit breaker size is 20 amp.
b. All CHX3 and CDX3 Series furnaces are supplied with a fuse disconnect switch box to be mounted on
the outside surface of the right or left side casing so a fuse disconnect can be mounted on the
furnace. Make the 115 volt supply connection in this junction box. A green screw and a strain relief are
provided in order to connect the power supply ground wire and provide strain relief for the 115 volt
power leads from the furnace in the fuse disconnect box. A disconnect switch can be field mounted on
the 2x4 box provided. If not, the disconnect switch must be located reasonably close to and within
sight of the furnace.
NOTICE: The hot surface igniter and operation of this furnace depends on correct polarity. The hot leg of
the supply circuit must be connected to the black line lead and the common leg to the white line lead in
the field mounted junction box. The hot leg must pass through the disconnect switch in all cases to
prevent the hazard of electrical shock when servicing.
IMPORTANT: The furnace must be grounded in accordance with local codes and with the National
Electrical Code (ANSI/NFPA NO. 70 or latest edition) when an external electrical source is utilized.
2. ELECTRONIC AIR CLEANER (EAC) AND HUMIDIFIER INSTALLATION
The ignition module on this furnace has designated terminals to control the operation of an electronic air
cleaner and/or humidifier. These terminals provide line voltage (110-20VAC) for the control of these
accessories. (See Figure 21). NOTICE: It is important to confirm that the operating voltage of the
humidifier or EAC being installed matches the output of this control. If not, a field supplied relay or
transformer may be necessary to provide the proper control and supply voltage for the accessory being
installed. See the manufacturers instructions for the humidifier or EAC for additional instructions.