My neighbor tells me he needs a new Honeywell oil burner control unit,
and they come in 3 time lengths, 15, 30, and 45 seconds. How do I
know which length to buy? I know it doesn't say on the furnace itself
and I'm 99% sure it doesn't say on the control box.

On Saturday, September 26, 2015 at 12:14:12 AM UTC-5, micky wrote:
My neighbor tells me he needs a new Honeywell oil burner control unit,
and they come in 3 time lengths, 15, 30, and 45 seconds. How do I
know which length to buy? I know it doesn't say on the furnace itself
and I'm 99% sure it doesn't say on the control box.

Is there a model number anywhere on the furnace? I'm down South where I've never seen Oil heat in a home. If you can find a model number, you could call a supply house or service company and perhaps find someone who could tell you the most common parameters used in your area. If you can't find a model number, describe the furnace to one of the service company techs and he might be able to tell you. A picture posted on an image sharing site would help an experienced oil burner make a suggestion. ^_^

[8~{} Uncle Oil Monster

In alt.home.repair, on Sat, 26 Sep 2015 06:19:07 -0700 (PDT), Uncle
Monster wrote:

On Saturday, September 26, 2015 at 12:14:12 AM UTC-5, micky wrote:
My neighbor tells me he needs a new Honeywell oil burner control unit,
and they come in 3 time lengths, 15, 30, and 45 seconds. How do I
know which length to buy? I know it doesn't say on the furnace itself
and I'm 99% sure it doesn't say on the control box.

Is there a model number anywhere on the furnace?

Yes, and when I bought the house, second hand, it still came with the
furnace owners manual. And 10 years ago when I was too lazy to go
upstairs, I found the manual again online. And I've read all 8 or 12
pages several times. But the oil primary control unit has its own part
number, from another manufacturer. The furnace manual shows how it's
wired in, and even much of its internal wiring, but I'm 99.9% certain
that the furnace manual doesn't say how many seconds it permits without
a flame, or the control unit part number. (I would verify that now,
but I'm on another computer without all my files.)

Most people have their stuff repaired by furnace repairmen, who know
what to use, or fudge if they don't. (For example, there's a barometric
damper on my flue, and one service man just taped it shut, without
asking me or explaining why he did it . When I asked the next guy about
it, he untaped it, without telling me what is wrong with it's being
taped or what the purpose of the part is. Another examplle, the first
few years, the service men would measure the stack temperature (the
exhaust gas) maybe one or two other measurements (unburned
hydrocarbons--I should be so lucky) , with gauges, but after a few
years, they all stopped doing that. They'd look at the flame and think,
the flame looks okay, I guess. )

And then there was the guy who changed the large fan motor when it was
the squirrel cage that was squeaking. IOW, I don't look for the
cheapest but I still haven't found one really reliable company.

So if he used a 30 second timeout when he should have used 45, most of
the time the flame starts within a second, at most two, so it would make
no difference.. Hmmmm. Frankly after all this trying to get the right
time, I think I'd be better off with 15 seconds. Maybe my neighbor
would be too. I have never seen it take even 7 seconds to light, and
I've watched it quite a bit. But most of them on ebay are 45, and it
only matter on those occasions when it doesn't light. Now people might
have problems only once every 5 years, but when the time comes, some
people will keep pressing the reset button** and letting it run for 45
seconds, hoping it will light, even though they havent' identified the
problem and they've done nothing to fix the problem. It's so tempting.
Just push that button. And if you don't know that your filling the
firebox with unburned oil, there's no reason not to press it . (well
you have to let it sit for about 5 minutes before the reset button
works) (The idea is to turn off the oil if the flame doesn't light,
and I think to turn off the whole furnace, if there's enough dark smoke
to keep the cadmium cell from seeing the light of the flame. There is
also a high-temp switch that turns off the furnace if somehow it gets
too hot.)

**Of course a lot of people don't know about the reset button and don't
press it even once. It's behind a 20 by 40" metal panel that has to be
lifted and pulled out. And then if you see the red button, you have to
wonder. Why is it red? Is it like the fire alarm at school. Or the
launch button for ICBMs? I'd better not push it.

I'm down South where I've never seen Oil heat in a home. If you can find a model number, you could call a supply house or service company and perhaps find someone who could tell you the most common parameters used in your area. If you can't find a model number, describe the furnace to one of the service company techs and he might be able to tell you.

That's actually a good idea. My oil supply company should have guys
who know. I might do that had the problem not been solved. See my
other posts.

Two different years I've called them in Sept. or October and tried to
make an appointment to clean the furnace, and they say, not
surprisingly, We're all booked up. And I say, call me when the rush is
over, and they never do. What they should say is We're booked up until
January, and I'd say fine, how about January 10th?

A picture posted on an image sharing site would help an experienced oil burner make a suggestion. ^_^

[8~{} Uncle Oil Monster

I had an oil burner in our basement that was slow to light, altho it did light before the timeout timed out. Whenever the burner did not light immediately, when it did ignite after a few seconds, it was with a whumpf!!! that you could hear upstairs. That was how I knew it was time to readjust the ignition points where the spark was formed/located that ignited the oil.

The spark had to be in a certain position with respect to the fan/cone shaped oil pattern out of the oil nozzle. Due to vibration and actual wear of the metal points, an annual adjustment was generally necessary. After the first service call, and watching the repair man closely, I was able to do the positioning myself. But, it was good to have that backup timeout just in case.