My Therma-Pride furnace model OH5-85 delays from 1 to 5 seconds about half of starts and when it ignites it does with an explosion and pushes out smoke around the chamber inspection plate. We have changed nozzle and set the electrodes and the normal checks and each time it seems to to ok for a few days and then goes back to the same delay procedure. This has been going on for about 2 or 3 winters. Heats and runs good otherwise. Help.
Furnace firing delay
1 - 15 of 15 Posts
Joined
·
1,105 Posts
could be bad oil, an air leak somewhere in the oil line, so untill pressure builds up to give a fine mist to ignite its pissing fuel into the chamber, has a certified oil technician checked out the oil gun and system?
Joined
·
1,105 Posts
is your oil tank inside or outside? can you disconnect the oil line at the tank and fill a clear container with about a pint of oil and see whats coming out of the tank?
It is outside underground...I don't feel like oil is the problem....there has been at least 2 tanks full (550 gal) thru the furnace since the problem started....it can be fine one day and not the next.Thanx
When was the last time the burner had a full inspection/tune up? Oil nozzle, filter, pump strainer (if yours has one), oil pressure and suction readings, and combustion analysis?
Get a piece of clear tubing, and install it on the pump suction line. This will show you if there's air in the line.
Repeated hard starts are not good for the heat exchanger. Or your underpants.
Joined
·
42,671 Posts
Oil filter changed recently? Oil pump strainer cleaned or changed recently? What dimensions are the electrodes set to? Has anyone changed the air band and shutter settings? What nozzle are you using, GPM, angle and pattern. Example, .85 80° A? Was the ignition transformer tested?
Does it do it more often when its not as cold out, or more often when it is cold out.
Is this furnace being used as up flow or horizontal.
Does it do it more often when its not as cold out, or more often when it is cold out.
Is this furnace being used as up flow or horizontal.
Up Flow...outside temp has no effect...oil filter and strainer changed....electrodes,air band, shutter settings done by service guy...nozzle .65-80 degree W.....tried .65-80 SS same result....quiet today.
Joined
·
42,671 Posts
W and SS are virtually the same thing.
Did he do a smoke and combustion test/set up when he adjusted everything.
firing delay
Is there any thing that can be added to oil..(23 inches in tank ..250 gls) to help it clear up or possibly burn better? Slow picking up is way better than the big BANG though.
Put new pump....still delay....switched intake and return lines...same thing....transformer looked weak and yellow..put on new one...no more delay....oil looks dark but burns well...slight gurgle as first fires up then smooth....may have to put pickup in vent to get away from bottom of 57 year old tank...no problem....how far OFF BOTTOM should it be? 550 tank.
Is there any thing that can be added to oil..(23 inches in tank ..250 gls) to help it clear up or possibly burn better? Slow picking up is way better than the big BANG though.
Joined
·
42,671 Posts
Pumps better? In what way?
1 - 15 of 15 Posts
