atwood oD50, oD50cW On-Demand Water Heaters - Manuel (Page 7)

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2. Water pump is not functioning properly. Repair or replace
pump.
3. If the heater cycles as the pump cycles, a pressure
accumulator tank is needed in the water system. If you
have an accumulator tank, check to see if it has become
filled with water. If it has, drain it so that it contains air
only.
4. Air is in the water line. Bleed air by turning on all water
taps.
5. Water source pressure fluctuating too low causing loss
of flow, check incoming water source pressure, should be
a minimum of 30 psi.
burner ignites but Water Temperature is Too low
1. The water flow may be so high as to exceed the capacity
of the heater particularly if your supply water is very cold.
Slow the water flow.
2. The gas pressure may be too low. Be sure the gas flow
control valve is in full “on” position.
3. Check the gas pressure while the water is on at full flow.
The LPG pressure should be the “manifold pressure” as
shown on the specification label while the heater is
running. A gas-testing gauge should be installed on the
manifold tap so that it may be read while heater is
running. If it is too low, turn up the gas regulator to the
proper pressure. This should only be done by a qualified
technician.
4. The gas flow may be too low due to improper gas line
diameter (under 3/8 inch outside diameter). The gas line
may be excessively long (over 20-30 feet) or the on/off
solenoid at the tank (if you have one) may have an orifice
that is too small (under 3/16th of an inch).
5. Check the heater door louvers and flue pipe for airflow
obstructions and clean.
6. Check that the “winter/summer” valve is in the proper
position for the temperature of the incoming water.
Water Temperature Too low at lower Water flow
rates
1. Check that the “winter/summer” valve is in the proper
position for the temperature of the incoming water.
2. Be sure to momentarily turn hot water flow to high, then
back to the lower flow when turning on a water faucet.
This will bring the gas flow to the required higher setting.
3. For single lever shower controls you may have to adjust
internal temperature control to a higher setting to allow
for more hot water flow to properly activate the water
heater.
Water Temperature is Too Hot or no Temperature
control.
1. Fuel tank regulator is set too high and manifold pressure
as described above Have the regulator checked by a
qualified technician.
2. Check that the “winter/summer” valve is in the proper
position for the temperature of the incoming water.
3. Water flow too low for incoming water temperature.
5. Be sure there is a battery in the system. never connect
the heater directly to a power converter. Some converters
have circuits that are not pure DC. This can cause
malfunctions or damage to the heater and is not covered
by warranty.
6. Be sure that no water-mixing valve has been left in the on
position, using the showerhead as a shut off. This will
permit water to bypass the water heater and bleed cold
water into the hot water system. Always turn off both hot
and cold water valves after using.
7. Be sure that the bypass valve at the water plumbing
connections is in the “off” position. An open valve can
also permit water to bypass heater, causing it not to fire.
8. Locate the ECO, high temperature switch (two red wires)
at the upper left hand of the heat exchanger. Check for
open circuit condition. The ECO should be reset by
pushing the reset button when temperature drops below
160 degrees.
There is no ignition When Water is on (Power vent is
running)
1. Be sure the gas valve at the tank is “On”, there is gas in
the tank and the gas line is purged of all air.
2. Check that the ignition wire is plugged into the spark
tower on the ignition control and is not touching anything
else.
3. Check flame site hole to see if igniter is sparking from the
probe to the burner. Bend ignition wire to adjust to proper
gap dimension or contact Atwood or you’re nearest
authorized service representative.
4. Check that there are no cuts or breaks in the wire. Align it
so that it is not in contact with anything but the terminal.
5. Be sure that the power vent fan has 12 volts to it when
there is water flowing and there are no obstructions in the
flue pipe.
6. Make sure pressure switch is closed by checking for
voltage across terminals, should be 0 volts, if reading
12 volts check for flue obstruction or obstruction in sense
line tubing.
no Water flows from Tap When Tap is Turned on.
1. Be sure that water supply is turned on and that there are
no obstructions.
burner Turns on but Temperature fluctuates
erratically.
1. May be caused by excessive restriction at the water
outlets, showerheads, aerators or water strainers. These
should be cleaned and any showerhead flow restrictor
removed.
2. The gas modulating valve is out of calibration. Consult
Atwood.
Heater comes on but rapidly cycles on and off.
1. Water flow is too low. Increase flow at a tap. Clean all
aerators and shower head screens to assure at least .5
GPM of water flow