Re: [A/S] Atwood furnace acting wierd. PROBLEM SOLVED

["Silsby S. Pelissero" <silsby@xxxxxxxxxxxxxxxxxx>]

Hi Charlie (and other interested parties),

After having 2 different mechanics (because it did not fail for the first
mechanic in Santa Barbara, California) at 2 different companies look at the
problem it was solved and the reason I am writing is because I feel I should
share some of the valuable knowledge I picked up on how to avoid this
expensive problem.

You may remember that this furnace was new and had never really been used
because this was the first time we had camped during winter. The problem was
intermittent and the furnace lighted easier when it was warm outside (the
warm thing I discovered after sending my first email to the list).

As it turns out my new (purchased June 1998 a 1999 model) was shipped from
the factory with the gas regulator set at 8 water inches of pressure. Atwood
recommends 10.5 to 11 inches for the furnace.

When it got cold outside the gas pressure dropped even more causing the
electronic circuit board to try ignition (up to 3 cycles which is a factory
setting) and finally it tried so many times that it burned itself out;
partially.

A test light put on the wires from the thermostat to the gas valve did not
pick up this problem. But the test light on the wire to the ignition
whatever showed a problem intermittently. So it was determined that the
circuit board was bad.

It was replaced and luckily it failed because there was the other
(regulator) problem.

When the board was replaced AND the gas regulator valve was turned up (he
said never do this without a gauge) the furnace worked perfectly and now
when it lights I hear the electronic ignition click once maybe because it
lights so fast (not many clicks and cycles as before prior it ignition).

He told me a couple of things to avoid:

1) If you are dry camping never run your furnace if your battery condition
is below 11 amps. (I didn't remember if I had ever done this because I know
I stored my trailer once or twice, plugged it into shore power but had the
power converter switch shut off. The furnace draws it's power from the
battery (12 volt) always. Low voltage will burn out these boards.

2) Always store the trailer with the thermostat OFF. It can drop below it's
lowest 50 degree setting at night run at night but not during the day
(depending where you live) you'll never here it and get into the same low
voltage situation if you are not plugged into shore power.

3) If I had my refrigerator serviced last year (which I didn't because it
didn't say anything about this in the Airstream Owners Manual. Sidebar: If
you use your refrigerator a lot of the time on gas, service the chimney and
burner once a year; mostly electric at least once every 2 years). Anyway, if
I had my refrigerator serviced they would have discovered the low regulator
pressure and would have fixed it then.

4) The reason my stove and hot water worked fine is because the water heater
has a different combustion chamber design that is not as sensitive to gas
pressure and obviously the stove/oven  ignition is self explanatory as these
use very little gas pressure at all.

Thanks for the Christmas present Charlie !!!

Here are some responses I received from various technicians from using the
information you sent me at the service departments:

- "Because you describe the furnace as "(when the temperature in the trailer
drops)
the fan comes on, I can here the electronic lighting device click..." , that
says the thermostat is working normally and the problem is in the furnace
it's
self". 

This helped me a lot and saved me money when talking about the problem to
the service people. Cut through the red tape as it were.

- "And since the installation is a straight forward one, there should be no
"extra charge" because it is in an Airstream".

Ditto.

"It could be something as simple as a loose or oxidized connector on the
circuit card"

- Ditto. Told them I had checked for this.

"to a bad circuit card".

BINGO! + plus one other thing but I'm really happy that I found out what
caused the circuit board to go bad in the first place...

Silsby

PS. I think it's within the list server protocol to mention the excellent
service I received from
TRAILER HITCH RV CENTER - in Pismo Beach, California (805) 773-5448 for
squeezing me into their busy vacation schedule. The mechanics name was Bill
and he was great.