Is this the proper way to check a furance heat exchanger or not?

Jim Mueller

I would like to know what are all the proper ways to check a 20-year old furnace heat exchanger for cracks? Consumers Energy sent a company (Greater Detroit Heating & Cooling) to check my furnace for a noise it was making from my blower motor. When he was looking at it, he decided that he wanted to check my heat exchanger for cracks. He poured a large amount 4(64oz.) bottles of cold water into a running, hot heat exchanger. Is this the correct way? Do you think doing this would damage or crack the heat exchanger? If you think it would cause a crack please explain WHY or HOW. Your response and any help in this matter would be deeply appreciated.
e-mail jimmueller@wideopenwest.com

Einsiedler_2

it's ok...

this is one of the methods used when a proper combustion teste is not possible.

another method would be to burn sulphur inside the heat exchanger and check for strong sulphur emmisions at the registers...

better yet.... buy a boiler. (j/k)

regards,

Einsiedler

ernie_3

disagree

2 gallons is a lot of water to pour in a hot hot exchanger
A smoke bomb test is a good way to test the integrity of an exchanger. I was never a big fan of the H2o test. Hot metal can fail (crack) when cooled suddenly. My rule of thumb is if the furnace is 20 yrs old it's time for replacement anyway. The old timers used to sit a shot glass full of liquid spearmint (old pharmacys carried this) in
the chamber and shut the unit off. If the pleasant smell of spearmint wafts into the living area, the furnace lacks integrity.

Mitch_4

It may be a method but its not a good 1

Combustion analyser is the best way...bar none.

I do not use cold water. Metal shock will "help" find a crack by making one. on a cold exchanger its ok.

For a hot exchanger, use a lit taper. turn off the burner and insert into the heat exchanger. if the flame wavers from the blower operation, you have a crack. If the flame is stable, you probably do not. I will usually run it up to limit if I do this test.

The peppermint idea is a great one, but be sure to have the filter rack cover and blower doors in place so you don't draw some odour through those openings.

If there is any suspicion, but you are not sure. remove the innerfront panel, or some older furnaces (Like Clares, Beach to name some) you can remove the rear panel and do a visual inspection of the exchanger.

I must point out the the water method will allow water to enter various areas fo the furnace.The heat exchanger is connected to the innerfront panel and sealed (usually( with a fiber roping/insulation. It is NOT watertight, and you will see some water from this are. it is NORMAL. same if it shows up in the blower compartment. I have seen this used as a reason to sell a new furnace. (A good indicator is if he tells you it is condemned, but he won't report it to the utility, or put it in writing with his certificate/technician# on it)

If water enters the BURNER area and is running down the wall of the exchanger. it is trash.

That being said, at 20 years old, its time for a new one anyway. Do a heat loss. even if it was correctly sized when it was put in, odds are in the last 20 years you haveadded insulation, new windows/doors, etc. Get the right size, and check for adequate air supply (unless you go high eff, sealed combustion) Inadequate supply because you have tightened your house envellope can result in CO. (ask Mark E or do a search for CO here on the wall. There is no shortage)

Good luck.
JMTC (just my 2 cents)

Mike