THOR Jayco Precept 2021, Owner'S Manual, Page: 125 / 173

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Section 8: Plumbing System
NOTE: Water heaters in certain models will ONLY have a single LP Gas
water heater switch. These units will not heat water electrically.
Make sure the water heater is filled with water before
use as even momentary operation of the water heater
without water in it may result in damage to the tank
heating element and/or controls.
Double check the
bypass valves , make sure they are set properly.
Always open both the hot and cold water faucets
when filling the fresh water tank to allow air pockets
to be forced out of the water heater.
Water heater switch (if so equipped)
The “propane GAS” switch enables propane operation of the water heater, and the “ELEC-
TRIC” switch enables electric operation.
Water heater bypass
Use the factory installed water heater bypass, available in most floor plans, to avoid filling
the entire water heater with RV antifreeze. See the
Utility Center
section for details on using
the bypass system.
High altitude deration
Operation of the water heater at high altitudes may require derating. If the water heater is not
properly derated, lack of sufficient oxygen for combustion may produce improper burner
operation. Pilot outage caused by burner lift-off or sooting from a yellow burner may occur,
indicating the possibility of carbon monoxide. You may also notice a lack of efficiency in
heating the water because of incomplete combustion of the burner at these higher altitudes.
Consult with the local propane company, your dealer or the water heater manufacturer for
proper derating of the water heater. Change out of the orifice (derating) should be done by
the dealer or a qualified service agency.
Pressure and temperature relief valve
The temperature and pressure relief valve is designed to open if the temperature of the water
within the heater reaches 120° F, or if the water pressure in the heater reaches 150 pounds.
When this pressure is reached, the pressure relief valve will open and water will drip from
the valve.
NOTE: It is important that once the RV has returned to lower eleva-
tion (below 4500 feet) any high altitude deration or other adjustments be
reversed for proper operation of the water heater .
Do not place a valve between the pressure and temperature (P&T) valve and
the tank. Do not remove or plug the relief valve under any circumstances.
Anode Rod Replacement Chart
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