Smoking in the Garage

[shilala]

Originally Posted by omowasu

There are a couple really good HVAC guys on the forum that may be able to chime in on this one - here are my thoughts...

First, having the furnace in the garage should not present an efficiency issue. The furnace heats recirculated air from the return ducts in your condo and does not intake air from the garage to push into the living area. If it did, that would violate a number of building codes...

The furnace will draw air from the garage in for combustion if it is a gas furnace, but the combustion air is not pumped into the residence. In modern HE furnaces, the exhaust from the combustion air is recirculated into the heating element and moisture is extracted for delivery to an outside vent.

I would NOT recommend insulating the furnace area door, as you may starve your furnace of combustion air which could cause a TON of problems.

Rather, I would suggest going to the hardware store and getting some of that aluminum tape. Use the tape to seal around the filter assembly where air may accidentally get sucked in, and seal any holes or vents in the return duct that are in the garage. You will need to remove the tape to change the filter, but its a very minor inconvenience. That should give you plenty of air sealing, and the combustion will help get some of the fumes out of the garage.

Just to add to what Scott said...
If smoke is getting dragged in the house via the furnace, it's because it's being sucked into the cracks in the return ductwork that's present in the garage, or into the return side of the furnace itself.
That's super easy and mega-cheap to fix. Grab a few tubes of duct sealant and seal all the seams in the return duct. Seal the area where it connects to the furnace. Miss nothing and don't be cheap. You can buy 2 tubes of mastic for the price of a cigar.

It'll be tough, if not impossible to seal everything without taking some stuff apart. You really have to get everything to be 100% sure no smoke gets sucked in the house via the furnace. Even if you get 90% of the stuff sealed, you'll be in much better shape.
You'll also need to seal the around the ductwork where it penetrates the wall or ceiling and enters the house. Should have mentioned that earlier.

This will also raise the efficiency issue you mentioned. Having the furnace in an unconditioned space like the garage isn't ideal from an efficiency standpoint, but those leaks provide fresh air to your house. That's a very good thing. The air in your house might exchange once in a day and that keeps it from growing stinky from being shut up all winter.
If you're dragging in gas, oil, and cigar stink from the garage, not good.

If you seal her up, the efficiency loss from the furnace being in the garage will be negligible. All you will be losing is a small amount of heat in the system. It's so not worth talking about that I've wasted too many words already. You'll not need to consider it ever again.