Oil furnace starts back up when you turn power off and then on to the furnace

krplun

I have a peerless cast iron boiler with a becket burner. From time to time it decides to stop running and won't start up again. if I turn off the power to the furnace for a small period of time (half hour or more) and then turn the power back on the furnace starts working again on its own. It will run ok for a day or two and then the cycle starts over again. Do you have any ideas of what's causing the problem? I can't call a furnace person in because if I can't recreate the problem then I'm afraid he'll be changing parts that may not need to be changed. Thanks in advance for your assistance..

DZoro

If the last service on the boiler has been a year or so, then call for service. Let him know the issue, could be loose connection, at boiler or thermostat, or other depending on how the system is controlled.
D

Jon_blaney

How old is the burner? When does it happen? When it has been running a lot or is it when it cold starts? I have had two different burners go on lock-out for no apparent reason. Turned out to be bad spark. If turning off the electric power works, my guess is the igniter coil.

Jellis

there is certainly an issue with a control in your system. Could be a number of things wrong. If you are handy with a multi-meter you can figure out where power stops and that will tell you whats wrong.
If a technician is able to look at the system while it is shut down it shouldn't take long for him to figure out the problem.
I would certainly not continue to run it like this. a safety in your system may be malfunctioning

HVACNUT

Is it a newer system?
What brand/model primary control (reset button) and aquastat?
Its possible either of those could be could open to the load side of the burner circuit and interrupting power off and on will reset it so to speak.
On an older primary (R8184G) or similar, the relay will hang up.
If its happens again try giving the primary a couple taps with a screw driver handle. If she fires, there you go.

STEVEusaPA

Sounds like heat affecting component(s).

If I were called (and I work for myself), I'd come out, test the components, try to recreate the situation.
It's possible it's a marginal ignitor/transformer, or some loose connections, or a faulty/failing component-which can be properly checked.

I had one where it worked fine until it approached high limit. Then the relay on the mechanical triple aquastat started rapidly clicking. If I would've hit the reset, and watched it for 5 minutes I wouldn't have found it. So it takes some investigating.

krplun

The boiler/burner is 20 years old but in great conditon. It seems to happen after its been running all day. I've been turning the furnace off at night and when I ge up and turn the power on it starts right up on its own.
It has a triple aquastat relay type L8124A,C and I did notice the relay vibrating and the transformer to the left of it was hot.
The oil burner control is a carlin model 48245.
Does this shed any light on the problem? Worse case I will call someone in. Thanks again for your help.

STEVEusaPA

It's a start.

After a long run and it's hot, seeing what happens when it tries to re-start could help. The primary control is not locking out so maybe the relay in the aquastat is chattering or locking up, not sending a signal to the primary control via B1 terminal.
With the power off, did you check all the terminals? I would carefully pull/push/tug on wiring while it's running, carefully push on the board, but I don't recommend that to you. I'd let a pro do that. I'd also check all voltages, incoming and operating for clean power.

A data logger like OnWatch may find it. It would show a call for heat, and no power going to the primary control. Or you're going to have to get lucky and catch it. I've used mine a few times. Once it took 3 months of logging data to find the problem.

Again assuming all standard checks were performed.

BTW, do you have an electrical thermal shut off switch above the boiler? Just curious.

Although I'm not a parts swapper, I might swap out the aquastat to see if the problem persists. You shouldn't have to shut off your boiler every night.

krplun

Yes i do have an electrical thermal shut off switch above the boiler.
Also the ignitor is a Sid Harvey t-92 with a primary of 120 and a secondary of 10k. The date on it is 0612.
I considered switching out the Aquastat but it costs around $200 and I wanted to check with you all before considering it.
I did check for any loose wiring but will do so again.
I'm sitting next to the furnace now waiting for the problem to happen. I will check the voltages again when the problem occurs to see if that might pinpoint the problem.
Thanks again for your support with this....

DZoro

What thermostat are you using?
D

krplun

I have 3 zones. 2 have the honeywell rth2300 programmable thermostats. The third zone is connected to a hot water tank which is heated by the furnace. Thanks

HVACNUT

@krplun
Since the burner never goes in to safety and the Primary is newer. I dont use Carlin primaries so I Googled it. Only intermittent ignition. And if not already done, remove the jumper for the 15-45 safety to make it 15 seconds. I dont know a reason they would offer a choice.
I agree it might be the aquastat. If your going to replace it, look at the Hydrostat 3250 Plus.

krplun

Again really appreciate you all taking the time to respond. Just so I don't leave everyone hanging - the furnace hasn't had a problem since I opened this blog. So whatever everyone is doing keep doing it! lols

STEVEusaPA

Glad it appears to be working. Sometimes just opening up things and checking wire nuts and connections does the trick.

Another thing I thought of, or forgot, is if you have a thermal imaging camera, to point it at components near the end of a long run cycle, just to see if something looks abnormally hot. Of course that's subjective as you don't have a baseline comparison, but being you're putting in some time sitting and staring at it, maybe point a Flir at it and see if anything interesting or curious pops up.

SuperTech

Reading what was stated it certainly sounds like a faulty aquastat. The relays on the old mechanical Honeywell ones don't last forever. I would install a new digital aquastat, Honeywell L7224U. The 3250 hydrostat is ok as well. The L7224U will also provide you with the capabilities to run outdoor reset and save oil. It's always nice to be able to perform an upgrade and repair at the same time.

krplun

Hi everyone before closing this out I wanted to first thank everyone for their input. I really appreciated all of you taking the time to share your thoughts. Second I wanted to let you know what the problem ended up being. It was a faulty primary controller. It finally got to the point where it was failing consitently. When the problem happened and I tapped on the controller the furnace started. I've been running with the new replacement for a while and all seems to be well. Thanks again, Many blessings to you all. Keith