SECTION 4 –
APPLIANCES AND SYSTEMS
4-8
Normally there is an air gap at the top of the
water heater tank which acts as a pressure buffer.
In time, however, heated water may expand and
fill this air gap, causing a slight increase in water
pressure. This may cause the P-T valve to “weep”
until the air gap is manually replaced.
To Replace the Air Gap:
1. Turn off the water heater switch and incoming
water supply (city water and/or demand
pump).
2. Open a faucet in the motor home to relieve
water pressure.
3. Pull the handle of the P-T valve straight out
and allow water to flow until it stops.
4. Let the handle of the P-T valve snap shut.
5. Close the faucet and turn on the water supply
before switching the water heater on.
Manually operate the pressure temperature
relief valve at least once a year.
NOTE: If your water heater is equipped with the
Motor Aid system, it uses an extension
from the engine cooling system to heat
water in the water heater while driving.
The engine cooling system must also be
cold before opening the pressure-
temperature relief valve. See “Motor Aid
Water Heater” for more information.
MOTOR AID WATER HEATER
–If Equipped
The motor aid uses heat from the chassis
engine cooling system to heat water in the water
heater while driving. Hoses are routed from the
engine to a heat exchanger surrounding the water
heater tank.
Under normal conditions, the entire contents
of the water heater can be heated in about two
hours or 100 miles of driving. This means you
can have hot water at the faucets immediately
upon arriving at a site.
The motor aid also increases the capacity of
the engine cooling system, allowing the engine to
run cooler under many conditions.
CAUTION
Operate this valve only when the water
heater and engine cooling system are
cold!
Water Heater Exterior Service Access
Lift handle straight out to open P-T valve
when water heater is cold*
