Yours is the simpler post to answer, so you're first.

On Sat, 15 Nov 2014 18:47:45 -0800 (PST), wrote:

What is going wrong with your control unit that makes you want to replace it

Late last winter, it stopped turning the furnace on. I took off the
cover and noted the relay and that when I pushed the relay down with a
wood stick, the furnace went on. Letting it run for an hour, or two if
it's cold, once a day, works fine except if the night is especially
cold. I have a whole spare burner, from when a neighbor replaced his
identical furnace, so I have a spare control unit, but I don't KNOW that
the control unit is good. Possibly, that's why he bought the new
furnace.**

They are pretty simple

Usual problems would be with the high voltage transformer which by the way can be very dangerous to work with and is not really part of the control unit

That seems to have failed just a couple years ago, and I replaced it
with my spare.

Other usual problem is with the flame sensing electric eye

I wipe that off whenever there is trouble, but it's never been dirty.
There is a spare one on the spare burner, if I need it.

The rest is a few relays and the 24 volt xformer

The 24volt xformer failed 6 weeks after I bought the house. The house
was only 4 years old. I had 3 guests from NYC. I was the first one
to have bought a house, so I felt like a big shot. Saturday at noon on
July 4th weekend, the AC failed, because the 24v transformer failed.
Sunday morning at 8 the water stopped.*** and Sunday at noon, ALL the
electricity failed. **** More below

What problem are you having

Nothing yet, but I had planned to replace the control unit today, or
soon, so the thermostat will control the heat again. Then it occurred
to me in more terms that maybe the spare one won't work. I know myself
and I won't want to go back to my manual system. And even though $72
is a lot to spend on a furnace this old, it's better than rushing to buy
a whole new furnace at the most expensive time of the year. Plus I'd
have to clean the basement to give them room to work.

So if I put the spare in and it doesn't work, I wanted to know if one of
the ones online would work for me.



And since yesterday I found this for only 40
http://www.ebay.com/itm/Honeywell-R8...em35d3f6 cf2c
It says Beckett but it seems to me it's an On/Off switch and all it has
to do is accept input from the thermostat, the CD sensor, and maybe
something else, and send output to the fan motors and the ignition
trasnformer, but that all the decisions, all the temperature settings,
are made by other things embedded in the furnace that wouldn't be
changed, and that just about any control unit will replace any other.
(I don't have a solenoid on my oil pump.)

And this one for $127 even has the same arrangement of connection screws
as mine does!
http://www.amazon.com/Honeywell-R818...ustomerReviews

For some reason, I've sort of given up plans that this would work, a
Beckett 7505A 0000 GeniSys
http://www.ebay.com/itm/Beckett-7505...em19f402 066f
$72 + 10 shipping at this Amazaon store but only 52 dollars + ???
shipping at Newegg. (I thought they just sold computer stuff. )

Mark

**(I asked him if I could have the burner, and he asked the furnace guy,
and both said yes. I should have asked if it worked. Don't remember.
A couple years ago, I used its ignition tranformer, when I think mine
broke. (I generally have a hard time believeing things are broken. I
have an all-in-one printer here that someone gave me because all it did
was display a code, and I can't throw it away because I'm sure if it
sits in my house for long enough, it will start working. Maybe this
feeling comes from my fixing so many things, from the age of 8, without
knowing what I did. But my ignition transformer must have broken
because when I replaced it, the furnace worked again)


***The builder didn't take many shortcuts, cut he did on the water
pipes. The gravel may be too coarse, but for sure, he used the wrong
pipes. They should be somewhat flexible and they're not, so when a
truck drives over a place where the pipe is on the corner of some
gravel, the pipe breaks. It's happened about 6 times in the last 31
years. The water mains circle the n'hood, and there are 6 or 10 or so
valves and it was designed when there was a leak that only two valves
would be turned off so only 1/6 or 1/10th, 60 or 36 degrees of the
circle, would be without water, but for some reason the plumbers always
say they can't do that and everyone goes without water.

****It's a 4 hour drive back to NYC. I think the guests stayed until
Monday afternoon or night, but now I'm not sure how, if the electricty
failed on Sunday, as I recall. I know we ate our meals out, and it
might not have been that hot, and I guess we were out except when
sleeping. . I will have to call one of them to remind me. The
electricity failed because the transformer that supplies 8 townhouses
failed, probably because everyone was using AC.

I also had trouble with the reset button for a while. I thought it was
a relay, and I looked for a relay that fit the spot, one with a built-in
button like some do have. Couldn't find one, but eventually the device
starting working fine again and has done so for 25 more years. I'm
dumbfounded by this. But ever since these two control unit episodes, I
had my eyes open for a junk one. I missed two or three, that were by
the curb when I was going out and gone by the time I got home, but I got
one before I needed it.