Our home is brand new. We have a natural gas furnace in the attic, and we've been using it for about 2 months now with no problems. For the past 2-3 days, however, I've been noticing a strange odor all around the house whenever the heat kicks on. It does NOT smell like rotten eggs. It's more of an acrid, ammonia smell, though not nearly as strong as household ammonia. My daughter said it smells like her hamster cage when it needs to be cleaned, and I would tend to agree. The smell is worse in some rooms of the house than others, and the upstairs (which has a separate thermostat and fan unit outside) does not stink. It doesn't smell like burning dust, and it doesn't get any better the longer you leave it on. When I turned on the air conditioner, it smelled really strange, too... almost like dirty socks. I did catch my dog urinating on the fan unit outside the other day, but I am not sure if the air from the fan unit even comes inside the house or not.

Any ideas as to where I should begin looking for the problem?

 

I suspect you need a new filter and a thorough furnace and evaporator coil cleaning.

 

Have you been doing any painting or wood finishing? The smell from that isn't normally as you describe from that though.

No air from the outside unit comes in to the house.


I think I'd do a good check of the filter and return air grill, esp if it happens to be down near the floor as opposed to higher up or on the ceiling.

btw...does the dog come in the downstairs part of the house?