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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I am trying to figure out why I am having a gh CO level at

Customer Question

I am trying to figure out why I am having a high CO level at the bottom area surrounding a Keepright furnace model N9MSB1002114A1. A couple of things to keep in minde I don't have the intake vent going out. Is there a possibility that CO is coming out of there. The intake pressure that I measured yesterday was minus .89. Checked CO in exhaust it was not zero but not high to about 8ppm. Question is how do I know if I have a crack in the heat exchanger
Submitted: 1 year ago.
Category: HVAC
Expert:  Tim H. replied 1 year ago.

Hi, I'm Tim and I'm an HVAC expert here to help answer your question(s). Please provide all the information I ask for since I'm not onsite. At the end of our dialog you will be asked to rate my service, but please wait until then and all your question(s) have been answered satisfactorily. Thanks for your business!

I understand you are trying to determine if your heat exchanger is cracked. This can be done in different ways. But if you watch the burners when they light, do they shoot straight into the chambers? And do they continue to do that when the blower (fan) comes on?

Customer: replied 1 year ago.
I am a contractor myself and looking for second opinion . Yes the flames still shoot inside. This is a propane furnace. There is some yellowish orange at the tips of flame. Did a CO test at exhaust pipe it was hi. What I am trying to find out does this indicate a crack or a blockage. The furnace is in a CRAWEL space,and god knows what happen during summer. I was also surprise that my biggest reading was around floor area. Keep in mind that I didn't take the intake vent outside for different reasons. Comparing to last years results my CO was high, my O2 about the same my exes air was lower
Expert:  Tim H. replied 1 year ago.

If the heat exchanger was cracked, the flame would tend to "lick around" and not shoot straight into chambers. A reading of 8PPM in the exhaust would not concern me too much. There must be over 50 PPM for me to even start thinking about examining heat exchanger. That small amount could even be caused by gas pressure set to high.

Expert:  Tim H. replied 1 year ago.

It is usually not a good idea to draw intake air from the area around the furnace as you probably know. It must be fresh outside air.

Customer: replied 1 year ago.
The amout of CO was in the hundreds . I am still trying to debate if mice made there home in the heat exchanger during summer or I indeed have a cracked heat exchanger. All was well last winter so for this to happen sun deny in fall makes me a sispecion that critters have gone in . How I prove to customer or myself is what I am having problems with. As you know one will be under warranty and the other customer will need to pay for.
Expert:  Tim H. replied 1 year ago.

OK, I was just going by your original question where you said you checked for CO in the exhaust and got 8 PPM.

Expert:  Tim H. replied 1 year ago.

The best test for a defective heat exchanger is high CO (over 50 PPM) as read in the exhaust of the unit. Other signs are flame licking out and not shooting straight into the chambers and obvious signs of sooting.

Let me know if you require further help. Otherwise, good luck! Thanks for using Just Answer and please don't forget to rate my service as that's how experts get paid (thanks in advance for any bonus left). Otherwise experts work at their own time and expense. Feel free to post back with any additional questions.