High levels of CO in the basement

I have a neighbor who’s daughter has had to call the fire dept. 3 times in the last year because her CO detector would go off, the fire dept. would respond and the levels were elevated (she didn’t say how high).

She had a new furnace, not a high efficiency one, installed with all new duct work.

She had a new flue installed in her chimney with a new spark arrestor.

The house doesn’t have a fireplace.

After all of this she has had to call the fire dept. again recently and is worried that something is going to happen to her dogs. She mentioned that it only happens during the warmer months and she does have central air.

Does anyone have any ideas of what may be going on here

So if it happens in the warmer months is it when there is no need for heat? If that is the case then there has to be another source of Combustion. A water heater possibly? Many CO detectors alarm after a certain period of exposure time and at fairly high levels. So I would assume the Fire Department checked the level when they were there. A leak in the return could cause the back drafting of an appliance especially if they are natural draft. Turn the appliance on that might be spilling CO and try putting a mirror at the draft hood and see if it fogs up when the A/C, dryer or any other source of depressurization is happening and the natural draft appliance is on.

[quote=“rernst1, post:2, topic:98104”]

… A water heater possibly? …QUOTE]

My thought as well…
A change in the Furnace firing that was previously sharing the flue may experience the problem that you are describing. I have found this previously in other homes along with other factors.

Recommend a Level 2 Evaluation (required by NFPA Standard) of the current flue condition by a CSIA Certified Inspector as the prior and intended use of the chimney has changed.

It certainly doesn’t sound as if the furnace is the source, as pointed out above.

A gas fired water heater could backdraft as pointed out and a leaking return is a possible cause.

Another possibility often overlooked is a dryer that shares the same room. Dryers suck large amounts of indoor air outside and can create a backdraft for adjacent appliances under moderate to heavy use.

How old is the CO detector?

I did ask her about the water heater and she said that her HVAC guy told her that it was fine. I didn’t think about the dryer, good point.

I just started talking to her this week because she has been around a lot more because her dad (my next door neighbor) just passed away but I think that I am going to have to go over to her house and see what I can find out.

Derek, if she was just basing this on a store bought detector I probably wouldn’t be as concerned but she has had the fire department test it multiple times with their equipment and tell her that it is high.

Thanks for the help everyone.

Are the levels constantly and consistently high?

Or intermittent?
Intermittent would point to problems with flues, possibly back drafting due to changing exterior conditions.
If the furnace is HE then is the water heater orphaned?

Intermittent was also the situation with the dryer operation in the news a while back.

The woman did all her laundry on one particular day of the week. Of course this involved a lot of dryer operation. The gas appliance would back draft and those were the days she got headaches from high CO levels.

I believe she said that it happened 3-4 times last year then she had the new furnace (80% efficiency) and ducts installed and then just recently, in the last month, it happened again.

I will ask her what her washing drying schedule is like.

She lives alone, except for pets, so it may be that she waits until she has a lot of dirty clothes and then does them all at once.