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