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Mobile Home Furnace Repair
QUESTION:I have a Coleman mobile home furnace. They are all pretty much standard
sized. I recently purchased the home used, and am just getting around to
checking out the furnace as cooler weather is just weeks away. I do not have
my oil tank installed yet, and because of that, I have discovered a strange
problem. Read on.
I dismantled the furnace, cleaned all soot, the chimney jack, took the blower
out to be hosed off in the yard---all ship shape. And...the furnace does
actually run! Without an oil tank, I had to come up with a way to supply fuel
to the furnace just to "test" it out to see if it was going to work. So, I
used a thick walled, but flexible clear vinyl hose. I fitted this onto a
brass fitting that would screw onto the place that the copper fuel supply
line will go.
I bled the lines, got oil running out of the bleeder nipple, then closed it
off and the furnace fired up immediately. I noticed that the flame died, and
it stopped. I started it again, and the same thing happened. I noticed that
when it died, shortly before that.....the oil level dropped down the pipe. It
died out because there was no more oil being fed into it.
I was using the K-1 white kerosene for this test, as I had no #2 fuel oil on
hand. If I held the container and hose no lower than 6" from the height of
the oil burner, it worked fine. I let it run for quite a while, the blower
cycled on and off, and I checked outside to see what the stack looked like.
Nice clean clear heat waves, no smoke or soot. As soon as I move the oil down
to the floor, the suction dies out, then the flame dies out.
This is no good, obviously, because the oil tank will be at least 6 feet lower
than the furnace and at least 15 feet away total (line length).
Is there a suction adjustment? Or is a vinyl hose into a fuel can not a good
way to test it out? I'm not a furnace man, but I've been around oil furnaces
ever since I was a kid. I've fiddled with them from time to time. This
furnace sounds good, burns smooth, seems strong. Just seems as though there's
no suction on the fuel line. Not no suction, just not *enough* suction.
ANSWER: A couple of things....First, the tube is probably not very air-tight, so it
is sucking air, or, the tube collapses inside the fuel container due to
excessive suction.
You should make **VERY** sure that the original pump set-up wasn't a 2 -
line system, because you will blow the pump seal by running it as a one-line
system without removing the bypass-plug. That is one of the most dangerous
conditions you can have happen with an oil unit.
I wouldn't worry too much about the oil tank, just make sure that they use a
2-line system, and flare fittings on the copper oil lines, DO NOT use an oil
filter on an outside tank, you will rue the day you were born if you do at
20 below ( trust me ).
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