Checking a furance heat exchanger

Jim Mueller

I would like to know what are all the proper ways to check a 20-year old furnance heat exchanger for cracks? Consumers Energy sent a company (Greater Detroit Heating & Cooling) to check my furnance 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

Dan Foley

Heat Exchanger

I have used a water spray to find many cracks, holes and/or popped welds in heat exchangers. I have never attempted this with the furnace running, though. In order to properly access the heat exchanger it is typically necessary to pull the burners and the blower wheel, depending on the brand and model. Check out www.heatexchangerexperts.com for more information on heat exchangers. -DF

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Brian_24

Running a test with a combustion annalyzer will tell more than cold water. If a heat exchanger can't take the shock of cold water do you really want it in your house? I would be more concerned with static pressures of the system and what the draft gauge and the combustion annalyzer are saying. jmho.

Jack Smith

The laws of common sense must prevail here, dumping cold water on hot metal is just plain stupid. Anyone comes in my house and stresses my heat exchanger like that is buying me a knew one!

Dale

Cracks

See the Dan F. post below. No, that amount of water on a running furnace isn't a good idea. I hope the blower was out and towels in the bottom. As Dan said the furnace is warmed up if possible and a water spray is put in from the top, wetting down the outside of the exchanger. If there's a larger crack the water will run into the burner area if there's a smaller crack the water will darken it to make it much easier to see. If a tech sees a crack often the consumer can't and the darkening really helps. Penetrating oil or wd 40 works even better but there is an odor issue. Ellis Prach of heatexchangerexperts teaches in a full day class on the topic and althouth somewhat opinionated really knows where and how to look for cracks in all brands.

Jim Burke comfort zone

Checking heat x changer

You will need a good draft gauge
First install in peep door and record your draft readings with the blower not running then turn blower on if readings change you have a bad x changer.
or a smoke bomb also works any heat supply will have them.
Or find a pro to help it could save you a lot of money in the long run & your health.


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