Strange oil furnace problem - http://www.hvacmechanic.com/ Forums

Original message

dbc120

64.111.153.43

"Strange oil furnace problem" , posted Tue 7 Oct 23:33

Furnace does not fire up initially. Meaning, it will and does fire up but only when I quickly flip the tstat switch from HEAT "on" to "AUTO" and even then it is sometimes? Blower works fine and did all summer with AC.

I have replaced the tstat thinking that was the problem but nope. All wires are tight to and from furnace/tstat that I have access to. I cleaned/replaced filters and even the nozzle. Put about $400 into service and parts end of last season. So not sure what the problem is? And yes...full tank of fuel oil. Rheem furnace with beckett burner. About 15 years old. Any advice is greatly appreciated. Thanks!

dbc120

Replies:

djgilbert

24.164.88.246

"Re(1):Strange oil furnace problem" , posted Wed 8 Oct 06:41

Some of those older rheems had a isolation relay right above the power junction box, usually on the right side, contacts in the relay could be dirty and relay may need to be replaced, could have loose connections

Don

dbc120

64.111.153.43

"Re(2):Strange oil furnace problem" , posted Thu 9 Oct 10:07

OK- I checked all connections with IR (two blue wires and black) nothing was loose or look dirty.

But I feel the IR is still the problem and also because you were not the only one who suggested same.

Is it possible the IR just needs to be replaced? Do they wear out or break down?

If so I would consider buying and replacing the IR and take my chances that is the problem.

BTW, I can still get the furnace to fire up but now it doesn't seem to matter if I switch the Tstat set on HEAT from ON to AUTO or AUTO to ON..just switching it while the blower is on does the trick. Not consistently...but it does the trick.

Would appreciate a response and Thanks!

dbc120

208.111.219.75

"Re(3):Strange oil furnace problem" , posted Fri 10 Oct 14:50

To those on here who tried to help me thanks but please take note and put in your memory bank in case this similar issue comes up again.

The problem which I solved after much more internet research and trouble shooting/problem solving had nothing to do with relay switches. It ended up being a $6 cad cell replacement. Unplugged old one plugged in new one (less than 1 minute) problem solved. I hope others can learn from this because I would start here next time because at $6 even if it is not the problem it doesn't hurt to replace these little things now and then.

dbc120

dbc120

208.111.219.75

"Re(3):Strange oil furnace problem" , posted Fri 10 Oct 14:45

dbc120

jmar

69.243.100.59

"Re(1):Strange oil furnace problem" , posted Tue 7 Oct 23:57

check fan switching relay to see if contacts are closing should read o across if closed, verafiy 24vac to t t at burner.