Crack in Oil Furnace

[westmorelnd]

Im new to the industry but have developed a habit of holding the access door open with a screwdriver and the back of my other hand just far enough back to feel for a heat change when the blower kicks on after servicing and firing older oil furnaces. Well last month while servicing a customers unit I had the hair burnt off my hand when the blower kicked on and advised the customer of a crack. Well the customer called the company that installed the unit inquiring about the warranty and they came out charged the elderly lady $90.00 and told her there is no crack. Im concerned for her safety and am going back next week with the owner of the company to check again, Ive never used the smoke bombs before but will next week and would like to know just how bad a crack has to be for this method to work? Thanks for any input

[Twilly]

Twilli says use an inspection camera. Bon Jovi is on vacation so he is not doing any inspections right now.

[beenthere]

Ifs its a relatively small crack, the draft from the chimney could prevent the smoke from coming out.

A manometer works better. But you can use you draft guage from your fyrite kit and see the diff in the draft reading when the blower starts.



PS: A tight mech room with a return leak can pull the draft out the inspection door also.

[Moose]

See Twilli - part one.

[HeyBob]

The easiest way I have found to find a crack in the combustion chamber of an oil furnace is to pull the blower, turn the lights out, turn the furnace on, if it has a crack or hole in the combustion chamber I guarantee you will see it.


Now remember, this does not hold true if the crack is way up in the heat exchanger.


Obviously you did not find the crack or did not look after having your hand burned, which you should have, you may or may not have a crack, you have to find it also.

[Chauncey]

The correct way to find a bad heat exchanger on an oil furnace is to check flue content either CO2 or O2 will surfice. Check and record with fan off and then again with fan on any variance equals bad heat exchanger. Usually CO2 goes down and O2 goes up. Inspection scope will help verifiy the hole. Get out your contract and sell the job right there, get the deposit and do the job. Merry Christmas to all.

[in-trane-ing]

Anyone ever use salt spray w/ halide torch to find cracks in a hx

[Mr Bill]

Crack in the furnace? I guarantee you any crack head can find it fast.

[billygoat22]

Many upflow furnaces you can pull the back cover off and inspect the hx visually in a few minutes.

Or pull blower and view bottom half, cut hole in plenum and then check top half.

[selfemployed]

Anyone ever use salt spray w/ halide torch to find cracks in a hx

Heard of it but never tried it.

Westmorelnd - use the front of your hand from now on. Glad you and the owner are going back to check on it.

[skippedover]

The correct way to find a bad heat exchanger on an oil furnace is to check flue content either CO2 or O2 will surfice. Check and record with fan off and then again with fan on any variance equals bad heat exchanger. Usually CO2 goes down and O2 goes up. Inspection scope will help verifiy the hole. Get out your contract and sell the job right there, get the deposit and do the job. Merry Christmas to all.

IMO, Chauncey here is right on the money. Use your combustion analyzer and watch for the O2 change. You can see it change immediately when the blower comes on. He's right on target. Get out the contract and get it signed. No insurance company will pay off if the house soots and the unit was diagnosed with a crack or hole. But the inspection door method is truly bogus. Mind 'beenthere's comment about the blower sucking the exhaust out the inspection door in a tight room. That's the main reason the inspection door theory can't hold water. O2 and the analyzer no one can pick on. Solid evidence. FYI, they can also find burned out baffles in oil units. High stack temps when the burner is set to factory specs will show that and that's a big waste of oil at todays prices.