Crown Boiler CHC68-96 User Manual

Page 2

Only qualified service personnel shall perform installation and service.

Introduction:

These instructions list the steps required to field install a larger centrifugal blower
and ¾ HP motor assembly in any of the Crown oil-fired furnace models previously
noted. A blower upgrade kit will produce an increase in high-speed airflow to enable
the furnace to support an evaporator coil capable of producing approximately four
(4) tons of direct expansion cooling.

NOTICE

The blower upgrade kit is equipped with a ¾ HP, PSC-type, fan

motor. Electrical service to the furnace may have to be upgraded, in certain
situations, to support the larger motor.

Table 1: Electrical Power Supply Requirements for a Furnace Equipped w/

Standard or Upgrade Motors

Standard ½ HP Motor Upgrade ¾ HP Motor

Total Current (A)

10.2

13.6

Minimum Circuit Ampacity (A)

12.1

16.4

Maximum Fuse Size (A)

Installation:

A. Remove the Standard Blower / Motor Assembly

! WARNING:

If the heating system was recently operating, allow the

furnace to cool to room temperature before proceeding with disassembly.

! WARNING:

BEFORE disconnecting the furnace wiring harness at the

blower terminal block, use a voltmeter (or equivalent device) to measure
the electrical potential across the red and white wires and the orange and
white wires at the terminal block. No (zero) voltage readings confirm power
to the blower is off.

! CAUTION:

On horizontal / counterflow models, the auxiliary high limit

thermostat may interfere with easily removing the blower from the furnace.
To avoid damaging the thermostat, temporarily remove the thermostat
BEFORE removing the blower. Loosen two (2) sheet metal screws fixing
the thermostat to the blower support panel and carefully move the
thermostat to the side. Retain these fasteners for later reuse. It should not
be necessary to disconnect the electrical wiring from the thermostat.

1. Set the room thermostat operating mode to “OFF” and shutoff electrical

power to furnace at the disconnecting switch.

2. Remove the blower access panel.