I had 2 service men get stumped on my problem -- I'm hoping to educate
myself a little before swapping parts or trying someone else out of the
Setup: Heil 7000 "Super High Efficiency Furnace" (about 13 yrs old)
Symptom: Sometimes the pilot tries to light (click-click-click etc) but
gas won't turn on.
The electronic pilot control valve has 3 wires comming into it -- I've
been told these connect to sensors that tell the valve to shut down when
a problem somewhere else is detected.
Tempory workaround: Wiggle/press down on one of the 3 wires and it turns
on. You must wiggle it right at the terminal on the pilot control unit.
Wiggle a little more and you can cause it to shut off.
The obvious first step was to check for corrosion and make sure the
connections are solid and that the wires conduct and don't have breaks
in them. They all checked out okay.
I usually kill power to the furnace (nearby switch is handy) until it
shuts down before turning power on and wiggling/pressing on the
connections. Occasionally just doing this will cause it to function
normal, but not lately...
Tech#1 checked all the things that trigger the sensors, and verified the
scenarios that would send shut down signals don't exist/the furnace is
fine. Tech#1 even measured the voltage at each input to the gas valve
during the time it was trying to light and verified the signal to the
control box was good/as it should be.
The next logical guess was the little black electronic control box (on
the pilot/gas valve) was faulty. Tech#1 contacted Heil and was told that
this control box never goes bad, and if it had any problem it wouldn't
work at all. He also said the only way to replace this little control
box was to replace the entire gas valve, because even though the little
black box unscrews you cannot buy it seperately from the valve.
Ultimately suggested replacing both elec. pilot and the brain box.
Tech#2 witnessed the strange behavior, and quickly took to the "replace
parts" strategy but could not provide a reason for the actual problem.
Both techs had 15+ years experience, and said they had never seen this
type of problem/short term solution before, and neither were convinced
replacing the pilot/gas valve alone would fix the problem.
The problem is intermittent -- it existed the day I bought the house
almost 3 years ago, and I'd have to wiggle wires a few times per night
just to keep the house from getting too cold. Being late spring, I let
the probel ride out until the fall, when I planned on fixing it. But in
the fall, it worked flawlessly. It acted up a few time sin th spring. It
was fine this winter until about 3 weeks ago, and now it's acting up
numerous times per day. Sometimes the system seems to reset itself (all
motors quiet down and stay off for a few minutes and then it fires up on
its own. It was doing this frequently until recently and could maintain
a stable temp in the house. But I got bit Sunday morning, waking to a
cold house and had to intervene and wiggle/press down on the connections
to get it to light the flame and fire up.
Has anyone else experienced this type of problem? It just seemed strange
that both techs had 15+ years experience and said they had never seen
this behavior before, and I wanted to make sure we were headed in the