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HOW TO OPerATe yOUr WATer HeATer
If water heater has not been used for more than two weeks,
hydrogen gas may form in water line. Under these conditions
to reduce the risk of injury, open hot water faucet for several
minutes at kitchen sink before you use any electrical appliance
connected to hot water system.
If hydrogen gas is present, you will probably hear sounds like air
escaping through the pipe as water begins to flow.
1) Pressurize the water system by turning on pump or city
water pressure.
2) Purge all air from the system by turning on the faucets
until a steady stream of water flows.
3) Turn on the 12V DC power supply.
4) Turn on the LP supply at the tank and the manual gas
valve (if installed). The water heater will remain dormant
until a water tap is opened and the heater senses water
flow of at least 0.5 GPM.
5) Turn on the hot water tap to full open. The heater will fire
up within several seconds and hot water will flow from the
tap in the time it takes to traverse the lines from the heater
to the faucet. (If this is the first usage, you may have to
turn the water on and off several times to purge the LP
gas lines of air.) If the heater fails to light or the lockout
lamp (optional) illuminates, turn the power switch OFF,
then On to reset the ignition control.
6) To shut off the water heater, shut off the water.
7) Should overheating occur or the gas supply fail to shut off,
turn off the “On/OF” power switch.
a note about “navy showers” When Dry camping
It is recommended to take a shower just like you would at
home. That is, leave the water running through the entire
shower. The hot water system is designed to deliver a
continuous, comfortable flow of hot water and that’s the way it
works best.
Shutting off the shower with the showerhead button wastes
water. Each time this is done, the showerhead “trickles”, filling
the hot water line with cold water. This cold water has to be
purged from the line each time the showerhead is turned back
on. Tests have shown that this will not save water.
GAS VALVE
PRESSURE SWITCH
RELAY
FUSE
ECO
FREEZE
PROX
+ 12V DC
GROUND
COLD PACK
(OPTIONAL)
IGN. CONT
SPARK & SENSE
WIRING
SCHEMATIC
(GREEN)
(GREEN)
(RED)
(RED)
(PURPLE)
(BROWN)
(BROWN)
(RED)
(RED)
(RED)
(PURPLE)
(RED)
(RED)
(BLUE)
(BLUE)
LOCKOUT
LAMP
(OPTIONAL)
MPD 90211
m
caution
FirE
• DO NOT smoke of have any flame near an open faucet.
General informaTion
• LP and Water system must be turned on.
• Have gas pressure tested periodically. Should be set at 11
inches of water column with three appliances running.
• Drain water heater at regular intervals (at least one time
during the year).
• Drain water heater before storing RV for the winter or when
the possibility of freezing exists.
• Keep vent and combustion air grill clear of any
obstructions.
elecTronic iGniTion mainTenance
• The water heater comes factory-equipped with a fused
circuit board, which will protect the circuit board from
wiring shorts. If the fuse should activate, the water heater
will not operate. Before replacing the fuse, check for a short
external to the board. Once the short is corrected, replace
the 2 amp fuse with a mini ATO style fuse. Do not install a
fuse larger than 3 amps.
• If the fuse is good and the unit is inoperative, check for
excessively high voltage to the unit (more than 14 volts).
Winter operation and Winterizing Water Heater
It is not recommended that you operate water systems in the
winter. Any freezing of the water heater or other plumbing
components can cause severe damage that is not covered
by warranty.
for extended cold temperature use, contact
atwood regarding the oPTional freeze Protection Kit.
Winter operation:
1. Turn off water pump and the power and gas to the heater.
Open the pressure relief valve by lifting the handle to a 90°
position from the normal position. (Summer/Winter valve
should be turned to the “SUMMER”
position horizontal).
2. Open drain valve that was installed
at hot water outlet fitting of heater.
3. Open at least one hot and cold water tap in the coach.
This should drain the system.
Winterizing Procedure:
Before storing the system for the winter, the plumbing
system must be winterized. This can be done by either of the
following methods:
1. All water should be drained from the system. To do this,
open one tap at a time using compressed air to purge the
system of all water. Once purged, open the Pressure
Relief Valve and leave in the open position.
2. Follow recommendations of your coach manufacturer. Use
RV non-toxic antifreeze.
