Stretch wrote:

Don't touch the surface of the Hot Surface Ignitor with your skin. It
has been known for at least 20 years that will lead to premature
failure. If you don't know what you are doing, you would be better off
hiring a contractor to fix it for you. It would certainly be faster
and you would get a warranty as well. If you want to save LOTS of
money, turn the furnace off and leave it off. Then you won't need to
buy parts on the internet.

Not trying to be a harda--, just surprised what some people will do to
save a little money.

Stretch
(HVAC contractor in South Carolina)

Like you, the local HVAC people seemed to think I should leave my
furnace off indefinitely. I turned to the internet to keep from
catching cold. I would have been glad to pay more locally.

Last summer lightning hit my chimney and killed my AC. The 24V 3A
fuse was blown on the computer board in the furnace. To isolate
the problem, I disconnected the 24V leads going to the thermostat
and put in a 5A fuse. I would be standing by the power switch and
the bigger fuse would be less likely to blow instantly.

I found there was a short on the board and called the HVAC company.
I had a stool ready so the repairman wouldn't get his butt cold
and dirty.

He expressed gratitude for the stool. Then he saw the disconnected
wires and chewed me out. It seemed to go on for ever. With my
lifetime of experience getting into trouble, I didn't argue because
that would not have assured him at all.

He said the trouble was that HVAC men don't neccessarily adhere to
color codes, so he had no idea which wire went where. I said I
could tell him. He asked how. I said I'd made notes and diagrams
of the wires I'd removed, but it probably wouldn't be necessary to
get my notes because I'd used masking tape to fasten the thermostat
wires in the proper order. He said he would have done the same.

I said I thought lightning had shorted something on the board. He
asked how I knew. I said the transformer had hummed. He asked how
I'd known it was the transformer. I said I'd put my finger on it.
He tried it and agreed. He said he needed to hook things up
anyway. I told him the order of the blower leads and checked my
notes to be sure. This time the humming stopped. I said the short
had probably burned open. He agreed.

I told him I'd rebuilt the computer board after a flood seven years
ago. I said finding sources for the components had been a hassle.
He said that he simply replaced boards because a factory instructor
had told him a DMM would zap the semiconductors. I said I thought
that information was obsolete. I said it was true when I had
started, in the days of VOMs and germanium, but nowadays it seemed
all a tech had to watch out for was static.

He shook my hand and apologized for getting mad. I would have been
mad, too. I'd left the wires undone because I hadn't realized
wiring could confuse a pro. I was glad I'd met him because I found
him honest, competent, and reliable.

I could have gotten a new board through the internet for $150. He
quoted $400 and a wait of just as many days. I bought from him
because I trusted him. I said I'd like one of those diagnosing
boards because it would be good to be able to phone and tell him
what was wrong if I ever had trouble. He agreed that it would be a
good choice for me.

Two weeks ago the board said it was an ignition failure. One
component on the burner had one thin wire. The other had two fat
wires. A sensor wouldn't need two fat wires, so that was the
ignitor. It read open on a DMM.

I called the HVAC company. Their machine gave me a cellphone number
in case of emergency. I was pretty cold, so I dialed it. That
machine said they'd get back to me. After sitting by the phone two
hours in a cold house, it was hard to unbend my legs to stand up.
Apparently they were unwilling to speak to a hypothermic man on a
Saturday. I wouldn't be able to check until Monday, and I was
afraid the ignitor would have to be ordered, like my computer
board. I wanted to be sure I could get the part Monday, but nobody
I knew could think of a place that sold furnace parts. The
uncertainty that I could get it locally drove me to the internet.