Drain Valve And Access Panels; Relief Valve; Internal Circulating Pump; Vent System - A.O. Smith CYCLONE XHE BTH 300A Installation & Operating Instructions Manual

POWERED ANODE OPERATION
To insure a long, trouble-free operating life, the BTH-300 & 400
are equipped with a powered anode system consisting of:
1. A power supply with a built-in diagnostic LED.
2. Two titanium anodes.
3. Wiring harness with ground lead.
Replacement parts for this system may be ordered from A.O. Smith
Product Service Division; see BTH-300 & 400 parts list for specific
details.
POWER SUPPLY LED MEANINGS:
The power supply diagnostic LED is located in the bottom right-
hand corner of the BTH-300 & 400 control board.
Steady green light means powered anode system is functioning
normally.
No light means no line voltage or a defective power supply.
Flashing red light can mean (1) the heater has no water or
(2) a broken or loose connection has occurred.

DRAIN VALVE AND ACCESS PANELS

The heaters are equipped with a 3/4" drain valve.
An access panel covers the cleanout opening in the tank which is
sealed by a gasket and cover, figure 24.

RELIEF VALVE

At least twice a year, the temperature and pressure relief valve
should be checked to ensure that it is in operating condition. To
check the relief valve, lift the lever at the end of the valve several
times. The valve should seat properly and operate freely.
FIGURE 25
If water does not flow, remove and inspect for obstructions or
corrosion. Replace with a new valve of the recommended size as
necessary. Inspection of the valve should be performed at least
every three years. Do not attempt to repair the valve, as this could
result in improper operation and a tank explosion. In areas with
poor water conditions, it may be necessary to inspect the
T&P valve more often than every three years.
BEFORE MANUALLY OPERATING THE VALVE, MAKE SURE
THAT A DRAIN LINE HAS BEEN ATTACHED TO THE VALVE TO
DIRECT THE DISCHARGE TO AN OPEN DRAIN. FAILURE TO
TAKE THIS PRECAUTION COULD MEAN CONTACT WITH
EXTREMELY HOT WATER PASSING OUT THE VALVE DURING
THIS CHECKING OPERATION.
If the temperature and pressure relief valve on the heater discharges
periodically or continuously, it may be due to thermal expansion of
water in a closed water supply system, or, it may be due to a faulty
relief valve.
Thermal expansion is the normal response of water when it is
heated. In a closed system, thermal expansion will cause the
system pressure to build until the relief valve actuation pressure is
equaled. Then, the relief valve will open, allowing some water to
escape, slightly lowering the pressure.
Contact your water supplier or local plumbing inspector on how to
control this situation.
Two common corrections are listed in the Checklist and Service
Information which appears later in this manual.
ABOVE ALL, DO NOT PLUG THE TEMPERATURE AND
PRESSURE RELIEF VALVE. THIS IS NOT A SOLUTION AND
CAN CREATE A HAZARDOUS SITUATION.

INTERNAL CIRCULATING PUMP

The BTH-300 & 400 are factory equipped with an internal circulating
pump. This pump is maintenance free with no oil needed for periodic
lubricating.
CIRCULATING PUMP - FIGURE 26

VENT SYSTEM

Examine the vent system every 3 months. Points of inspection are
as follows:
1. Check for obstructions and/or deterioration of vent piping and
vent hood. Replace immediately where needed.
2. Vent pipe and vent hood screen should be cleaned of foreign
material and soot. The screen is located inside the vent hood
outlet and is accessible from the outside of the hood. Do not
reach inside the vent hood when the heater is in operation.
3. Check all vent system connections for leakage and reseal as
required using Hi Temp Silicone sealer or equivalent.
22
CAUTION