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Author Topic: sources of CO.  (Read 556 times)

Offline Sergroum

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sources of CO.
« on: June 05, 2016, 09:57:10 PM »
Good Day.

I've got a puzzling case I'm trying to crack. A furnace got tagged for producing CO inside the house. They changed the heat exchanger and said all was good. I came to do an AC maintenance and they asked me to test CO inside the house. Asked me to do what they did and put a CO detector right inside the supply duct, through the duct cleaning opening. I did that and I'm reading 3-7 PPM.

Mid effeciency Furnace with a B vent running straight to the furnace. No other gas appliances in the house (not even the water heater). Open basement, the house is 40 years old with old style insulation, so plenty of fresh air.

Gas pressure's fine, the flame looks blue, burners clean and properly set.  A barely noticeable dust burning smell in the house. I removed the old EAC and stuffed a 16x25x5 merv 11 inside and the smell seemed to dissapear.

Any ideas? What could be bringing this CO in? Ventilated and tested. CO accumulates only durning furnace operation. The head exchanger's brand new. It could've been improperly inserted, but then why is the CO I'm reading is exactly the CO the other guys said they read in their invoice? Also ... not looking too deep and just observing the flame and the burners, it seems to be accurately working and inserted well. It's a lennox mid effeciency, none of that 'assemble thy own heat exchanger stuff'. 58 Delta T.

It's a B vent chimney, so ... unlikely that it's plugged. Right? And if it was, I'd be reading massive amounts of CO and signs of moisture inside the pipe, wouldnt I?

Offline walker

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Re: sources of CO.
« Reply #1 on: June 07, 2016, 10:04:01 AM »
does the customer smoke in the house?

Offline Admin

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Re: sources of CO.
« Reply #2 on: June 07, 2016, 12:03:50 PM »
I agree.  I have seen cigarette smoke cause 11 PPM of CO in a house before.

I have read that VOC's (Volatile Organic Compounds) can cause a CO alarm to go off.  New furniture can cause this off gassing.

Also if there's any new construction going on around and they are blasting, it's possible the CO is entering the house through or around the floor drain.

Offline Sergroum

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Re: sources of CO.
« Reply #3 on: June 07, 2016, 08:56:16 PM »
Good thoughts. Alright. None of these things I can help with. I was just afraid I forgot and missed something blatantly obvious and left a house with a CO problem.