Dear RV Doctor, I am having a
problem with the pilot light on the hot water tank on my old motorhome. I can light
the pilot light, but when I turn the dial to the ON position, it takes a moment
for the ignition, and when the propane gas finally reaches the pilot light
area, the combustion is so strong that it blows out the pilot light and the
main heating flame too. This unit also has a refrigerator that I can
run on AC, DC, or propane. On this unit, with propane selected, after you light
the pilot light, it runs and cools the fridge automatically depending on the
temperature level that I set it to. I can light that pilot flame, but
after that, nothing happens. The pilot light just stays on and doesn't ignite a
flame to cool the refrigerator. I believe that both of these problems are
related, but I am not sure as to what the fix is. The hot water tank is near
the front of the unit, where as the Norcold refrigerator is at the rear on the
same side as the hot water tank. I appreciate any advice that you can offer in
solving my problem. Dan R. (Howell, MI)
Dan,
a couple things to consider; first on the water heater. There will always be a brief
delay from the time you move the control valve from "Pilot" to "On" before the main
flame ignites. The propane has to travel from the control valve, through the
orifice and down the mixing tube, mix with
some fresh air, before reaching the pilot flame. The alignment of this mixing
tube is crucial. As the gas flows through the tube it draws in air to mix with
the propane prior to it igniting. If the tube is not centered on the orifice
fitting at the control valve and in line with the angle of that fitting, then
turbulence will take place inside the tube and create an improper mixture for
combustion. This can cause pilot and main flame outage. Plus the pilot flame
should only encompass the very tip of the thermocouple. A too large or too
small pilot flame can also lead to pilot outage.
On the pilot model refrigerator,
the standing pilot flame will stay small until the temperature inside the
refrigerator rises above the setting of the thermostat. If the box is already
cooled it’s not likely to ignite the main burner until you open the door a
couple of times or put warm food inside. Now if the box is already warm and the
main flame will not come on, chances are the thermostat capillary tube is mis-positioned
or the thermostat has lost it’s charge necessitating a new thermostat. A few
tests by a competent Certified service technician will quickly reveal the exact
cause. But most importantly, for both the water heater and the refrigerator,
(as well as the other two propane appliances), is the delivery line pressure of
the propane. It must be set to 11.0 inches of water column. Being an older
coach, it’s probably wise to have a service tech perform a timed pressure drop
leak test as well as set the pressure regulator to the correct setting just to
be safe. It takes special equipment to measure, set the pressure and to test
the regulator, so unfortunately, this is one task best left to the
professionals.
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