Forced Air Oil Furnace wont start at all
I got a friends oil furnace that is having some issues. While I work in the HVAC, I'm more the installer for duct work and basic heat-pump/gas furnace systems. Not too good on trouble shooting, let alone oil systems.
The burner wouldn't start a little while back. He bought a new primary Honeywell 8184G-4009 thinking that might be it which it could of been. That did nothing. After trying to check things with a multimeter, we seemed to believe a contactor was bad. Basically it goes like this:
Common Wire & Call For Heat Wire (White & Blue), come from transformer into this contactor. When thermostat calls for heat it sends 24v through contactor which closes the switch on the other side of it and sends 24v to terminals T - T on the Primary control.
Well, I havent used a multimeter in forever and this is how we check. With the call for heat on, I had 24v across the coil side of the contactor. Across the other side I had nothing. Yet, if i take one of the meter leads and put it on bare metal and the other lead on one of the contactor legs on the switch side I get 24v. I believe when we first checked it across the switch side with it calling for heat I got 0 because thats what I would see with it being closed? Something like that my friend explained. I also was getting voltage at the T - T terminals too.
So anyways, we changed that contactor with another one, Honeywell 8222D which the guy at the supply house assured me it would work. Hooked it up and the burner kicked on for about a minute then it kicked off, then on for a few seconds, then off again, then back on for maybe one second and then off again and I powered it down then.
Since then, I get nothing now. Tried getting a new primary and a new contactor but nothing. Don't even get the red light to come on when we manually trip out the safety on the primary.
Checked line voltage going into the primary/junction box. Good there, triple checked the wiring. Good there. The blower fan will start up and run so that tells me that that transformer there isn't bad?
Before I was told to just directly bypass the contactor and jump out the T - T with the 24v source. I did that and it was working. However when we try it now we get nothing. I was told not to leave it like this because it could harm it. Which I did not leave it like that, just touch the leads to the primary for a few seconds to see it run.
So maybe the R8882D is not correct? Any help would be awesome as well as what exactly this contactor is there for and what it does because I do not understand why you can't just run the 24v leads directly to the primary.
Last edited by jpingra5; 10-01-2011 at 08:00 PM.