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What is a cracked heat exchanger?

At a recent inspection I was able to detect a defective gas furnace with a cracked heat exchanger which had been producing low level amounts of carbon monoxide some of which was entering the home. The house did have an alarm type CO detector but because ppm was under 50 the alarm dit id not activate.

The gas company "Red Tagged" the furnace confirming my judgement. My client's had a new furnace installed prior to them moving into the home. The sad part of the story was the home had been inspected about a 10 days prior and this was not reported. The sellers were upset because they assumed that I was wrong with my inspection report.. I usually see a couple of these a year. The small rust mark is the crack, there were 4 more carcks we we're able to see.

Everybody should have a digital readout style CO detector in their home in the bedroom hallway. Consistent reading over 9 ppm is not an emergency but you should look for possible sources. Never operate an "unvented" gas fireplace without a open window in the same room.

Posted by Paul Luczyk, ASHI on 05/14/2008 01:21 AM

Comments (22)

carbon monoxide danger, cracked heat exchanger, defective furnace

Post is included in group: Ask the Home Inspector
Post is included in group: Ethics and the home inspector
Post is included in group: Puget Sound - WA Real Estate
Post is included in group: Inspection & Real Estate Nightmares

22 Comments on What is a cracked heat exchanger?

MAY

2008

Paul, good job, and nice catch! Good advice about the envented gas fireplaces, we have one in our basement that we don't even use. (too costly) No sense taking a chance with carbon monoxide.

Paul,

Better yet do not install or use unvented gas fireplaces. Besides the danger of using up O2 in the house they produce a lot of water vapor which results in condensation in the home.

One thing I would point about your inspection, I know of very, very few inspectors who would dismantle a furnace to view a heat exchanger. It goes way beyond the scope of a home inspection and the expertise of home inspectors. The other guy didn't miss it, he wasn't looking for it.

I would have to echo James comment. It is beyond the scope to dismantle anything in order to inspect it. That should be left to a qualified HVAC technician. I can see how the client would be confused in situations like this.In one sense you are providing great service to the client by going above and beyond, but in another sense it leaves the client wondering why one Inspector didn't find it, and another one did. That would leave the client looking at that other Inspector as though he did something wrong, when in fact he didn't.

Okay as Paul Harvey says, "Now for the rest of the story". As James & Mike indicated dismantling equipment is beyond the scope of standard home inspection including my ASHI SOP. I did not dismantle anything. The other inspector did miss a yellow flame and small amount of CO at the heat register. The HVAC contractor verified my call and told the sellers they had to replace the unit. I had an opportunity to return during the new furnace installation and add a couple of photos to my collection.

Yea, I wonder how the other guy missed this. The sellers were more than confused because they hired this guy for their prelisting inspection. Oh yea, their agent recommended him.

Ah right on Paul. In that case then...good call. Abnormal flame pattern is definitely within scope and is something that should raise an eyebrow or two with any inspector.

I would add that most inspectors don't own CO detectors:)

JUL

2008

I do :) Paul you had me worried at first as well. I was trying to figure out how in the world you saw that crack without dismantling lol. Great catch!!

InterNACHI Ask the Inspector

I guess experience and paying attention to detail pays off for you. I would have called the other inspector and had a word or two with him.

SEP

2008

I would have to agree with Charles. I do not own a CO detector. Most HVAC systems in my area are heat pumps. Reguardless of how the HVAC operates I always tell the client and make the recomendation in my report to have their HVAC system evaluated at least once/year by a licensed HVAC contractor to promote efficiency and ensure that the system is operating within manufacture specifications and that these routine checks should start as soon as possesion of the property is taken.

With this I tell the clients that a licensed HVAC contractor will most likely conduct a more thorough evaluation of the HVAC system than I do. I have a lot of first time young home owners.

OCT

2008

A blind man may have been able to find this one. probably would have burned finger tips though. Those older Rheem gas paks are notorious for cracks, and they seem to all be in the same general location. I always take the time to remove all those screws to look inside those units.

Just a note, in case you didn't know, don't operate the burners with the covers off, or the flame roll out sensor will go off, and you will be paying for a repair bill.

It's amazing the stuff we find - if we look for it.

rheem

It seems like a very good idea to use a CO detector. Is the use of this type of equipment beyond the scope of the ASHI SOP?

Steve, the SOPs of all of the Associations I am aware of are "minimum" standards and the use of any of this sort of equipment would be considered "outside" of a "Standard Home Inspection."

Charles - You are everywhere! :)

Steve----remember Chicken Man? He's everywhere he's everywhere....:)

OCT

2008

Nice catch Paul, I always use a CO detector and if possible my borescope to see as much as the exchanger as possible. I have seen several cracks, on newer units, like you pointed out with no apparent CO after the unit was heated and the exchanger expands to close those smaller cracks. I have had 2 HVAC persons tell me that the small cracks I found relased no CO so there was no way it was a crack that what I was viewing was weld seams along the vertical walls. What can you do when the "designated professional " disputes your results. I had to go to these homes 2 more times to show them what I had seen. They ended up being wrong and apologized since they only used their CO sniffers to test.

DEC

2008

My daughter purchased an older home May 2008. The home was inspected by a licensed inspector. The inspector recommended they have a HVAC company inspect the furnace since the home inspector is not licensed to work on gas furnaces. My daughter did just that. The HVAC guy gave the system a clean bill of health. The seller (as part of the contract) purchased the house insurance. The policy was written. Now in December the furnace was not working properly Would cycle on and off normally producing heat and then die after about 10 to 15 cycles. The home insurance firm was contacted and sent out a technician. Technician found a defective circuit board and a cracked heat exchanger. The home insurance company will not cover the system because the heat exchanger does not suddenly crack, it would take a long period of time for this to occur. The system was installed in 1993. Do we have any recourse to go back to the HVAC company who inspected and gave the system a clean bill of health? If they did not miss the cracked heat exchanger additional negoitaions would have occurred with the seller prior to the purchase.

DEC

2008

Did your home inspector run the equipment? How old was the furnace? Unless there's mitigating circumstances I'd say the company has some responsibility to correct the problem.

I also had a recent inspection with a 35+ year old oil furnace that appeared to be on its last leg. I called for a furnace inspection and the HVAC guy indicated it was OK. Shortly after my client moved in this fall it quit. I told my client the guy missed something and he has responsibility to make it right. He first told my client he does not like to give a bad report on equipment because homeowners get upset when he does this. What a way to run a business. There have been a few home inspectors who also believe this method for growing their business. The HVAC company finally agreed to install a used replacement burner to get the family through winter.

Paul L

JAN

Nice catch. I was wondering how you got those pics! Flame color and attitude is very important to pay attention to.

I had a client that paid me for and inspection but the gas was not on. He wanted the furnace looked at but didn't want to pay me again. He said the furnace "looked," pretty good and I told him I hoped that he was right!

JAN

I was able to return to the site when the furnace was replaced and had access to view the heat exchangers.

Paul L

JAN

Good timing on this article. I have been having issues with some Realtors regarding heat exchangers and several of our HVAC companies (and a couple Electrical too) play to the Realtor and will tell them that a suspect furnace is "okay". Nevermind it's 35 years old and rust is flaking off the exchanger.

So, I'm in the market for a CO detector to back up my findings.

Any suggestions?

Paul D.

JAN

Paul,

Most guys use a Bacharach, some use Extech. They're many choices for a good CO meter. There will be many vendors at next weeks ASHI conference with all the meters to demo.

Good Luck.

Paul L

JAN

Thanks, Paul. I'll see if I can find some locally (rural area so I won't find any suppliers carrying them) at the HVAC companies. They're probably using higher end units but it'll give me something to judge by.

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