Gas and Oil Home Heating Furnaces - Oil Furnace Not Always Responding to Thermostat

I have a Williams gun-type, oil-fired, forced air furnace. Sometimes if I turn up the thermostat, it will not respond for maybe 30 minutes. Then it will start up by itself and run normally for maybe weeks at a time. It does not let the house get cold. It seems like it is some sort of overtemperature switch that resets automatically. Any tips on what to check? TIA, Brady

Have any more info ? Is AC coil dirty air filter clean ? Does it feel like its off on limit there at the furnace? Does the furnace feel hot when it dont come on? lots of ifs here.
Post back what you find out .

ED ;)

Have any more info ? Is AC coil dirty air filter clean ? Does it feel like its off on limit there at the furnace? Does the furnace feel hot when it dont come on? lots of ifs here.
Post back what you find out .

ED ;)

Sorry for the dearth of information. I had written a veritable tome, but before I could enter it, a popup window came up containing only a button marked "close". I couldn't do anything else, and when I clicked on it, I got kicked out of the forum and lost it all. When I just tried to re-enter the information, the same thing happened. Is there a limit to the size of the posts?

There is no AC coil. The nozzle, oil filter, and air filter have been replaced.
This happens so seldom that when it happened recently, at first I forgot that it had happened last year. It may have happened more often and I just didn't notice, because it came back on by itself before the house cooled down significantly. TIA, Brady

Response to my own post; I was afraid I was going to get kicked out again :)

Does it feel like its off on limit there at the furnace? ED ;)

Not sure what you mean by this.

"Does the furnace feel hot when it dont come on? " If you mean excessively hot, not that I can tell.

Thanks for taking the time to read this. Hope you are having a nice holiday! Brady

edit: Just thought of a couple of more things. I have noticed that sometimes when the blower comes on, the oil pump motor will shut off for a few seconds and then start up again. I had thought that maybe this was due to the weak transformer, but it kept on doing it after I replaced the transformer.

Also, the last two seasons I have switched from #2 to #1 fuel oil. I kept the same size nozzle because guy that sold me the nozzles told me to use the same one. I think that I read on this forum that the size would not be the same. Is that correct? I think that I will change back, because I found out from this forum that the #2 has about 30% more energy per gallon; I thought the only cost difference was the cost per gallon. I have an above-ground tank, but I will buy the anti-gel additive to keep the fuel from gelling from the cold. About the coldest it ever gets here is about -20F; would this additive still work at that temperature?

TIA, Brady

Hope everyone had a nice holiday.

Any more thoughts on my problem? :why_this:
The only other thing I can think to add is that my themostat is electromechanical, not digital. When it is in the nonresponding mode I can still hear it click. TIA, Brady

I have a couple of questions before I can make any judgements. Does your burner have a safety control mounted right on it or is the safety control in the flue pipe? You said mechanical thermostat, is it old or new? If it is old, can you tell me if there are 2 wires inside it or 3. The same question about wires would apply to the safety control if it is in the flue pipe. 2 or 3 wires?

Ken