Oil Furnace-Loss of flame

Tom_14

A client has a ThermoPride oil furnace with the tank above the burner. The burner fires for about 20-30 seconds then goes out. After about 10 seconds it ignites with a puff of smoke. After reignition, the furnace burns fine. There seems to be plenty of head on the oil lines. New 3/8 oil lines. The furnace was moved recently. Any ideas for the loss of flame?

Thanks in advance.

[Deleted User]

Air leak in the oil lines somewhere

including valves, and pump seal. Check the vacuum at start-up, running, and shutdown.

If you have positive pressure the whole time, I'd look at the pump itself.

If it goes into vacuum when it starts, look for wet oil lines somewhere.

Hope this helps.

Noel

john_35

loss of flame

That's right-air leak(s) in the suction side of the fuel system is what's causing you to momentarily loose prime on start-up. Actually what happens is the oil runs back to the tank on the off cycle because air leaks in thru the leak(s). It doesn't have to leak oil out either; which is what makes it so hard to find the air leak. Get rid of any compression fittings that may have been used in the new lines. Flare fittings are the ONLY acceptable type. Then go over each of the connections checking for loose or badly flared joints. It may turn out to be the fuel pump but that's less likely, assuming you didn't have this problem before you moved the furnace. Change all the gaskets on the oil filter too.

Tom_14

loss of flame

Still looking for the leak. All fittings are flare. I suspect the filter although new gaskets were installed. No seeps and the tank is 5 feet above. Thanks for the replies.

rob

Try a

Tigerloop. Should solve the problem unless you have air leaks on the suction side.

Tom M.

Tigerloop

should not be used below the level of the tank unless an oil safety valve is ahead of it. The tigerloop could overfill or worse. Also, the OSV only protects 3 feet down, anything greater is outside the manufacturer's instructions and could produce a siphon large enough to open the valve. You would have to locate the OSV at the tigerloop and not up at the tank.

A couple things to think about: If the tank is above the burner, why a two pipe system? If the second pipe was added when the furnace was moved, was a bypass plug installed?

Hope this helps.

eleft_4

air

Is it a plastic or nylon gasket under the cover bolt? If so just try a glob of RTV smeared around the hex where it meets the cover.

al