A.O. Smith 400A - Manual (Page 17)

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codes or contact the water supplier or local plumbing inspector on
how to control this situation.
WATER (POTABLE) HEATING AND SPACE HEATING
1. All piping components connected to this unit for space heating
applications shall be suitable for use with potable water.
2. Toxic chemicals, such as those used for boiler treatment, shall
NEVER be introduced into this system.
3. This unit may never be connected to any existing heating system
or component(s) previously used with non-potable water heating
appliance.
4. When the system requires water for space heating at temperatures
higher than required for domestic water purposes, a tempering
valve must be installed. Please refer to installation diagrams
on pages 30 through 35 in back of manual for suggested piping
arrangements.
HEATER WIRING
IF ANY OF THE ORIGINAL WIRE AS SUPPLIED WITH THE
APPLIANCE MUST BE REPLACED, IT MUST BE REPLACED
WITH 105°C OR ITS EQUIVALENT, EXCEPT IN THE BURNER
HOUSING. IN THIS CASE USE 200°C WIRE.
THE COMPUTER CONTROL REQUIRES A SOURCE OF STABLE
CLEAN ELECTRICITY FOR PROPER OPERATION. INSTALLING
THE HEATER ON A BRANCH CIRCUIT THAT HAS ELECTRONIC
NOISE, IS SUBJECT TO FLUCTUATIONS IN VOLTAGE LEVEL
OR HAS AN APPLIANCE WHICH GENERATES EMF OF
RFI INTERFERENCE CAN CAUSE THE CONTROLLER TO
MALFUNCTION. A HIGH QUALITY POWER CONDITIONER
MUST BE INSTALLED IF THE ABOVE CONDITIONS EXIST.
MALFUNCTIONS CAUSED BY A POOR ELECTRICAL SUPPLY
ARE NOT COVERED UNDER YOUR WARRANTY.
The controller is wired to the heater as shown in figures 15 & 16. The
model and rating plate provides the electrical information needed to
size the complete heater branch supply.
All electrical work must be installed in accordance with the National
Electrical Code, NFPA 70 or the Canadian Electrical Code, CSA
C22.1 and local requirements.
When installed, the appliance must be electrically grounded in
accordance with local codes or, in the absence of local codes,
with the National Electrical Code, ANSI/NFPA 70 or the Canadian
Electrical Code, CSA C22.1.
DO NOT ENERGIZE THE BRANCH CIRCUIT BEFORE THE
HEATER TANK IS FILLED WITH WATER.
NOTE: This controller is Polarity Sensitive. If the Hot and Neutral
Supply Voltage is reversed, the controller will not sense flame. Verify
polarity before connecting the unit.