Direct Vent to garage - foolish or outright dangerous?
I want to install my Majestic DV fireplace against a wall common with our garage. Rather then spend $800+ on their proprietery 7" vent piping to run about 20'+ over and up, what would be the problem with connecting the inner 4" hot pipe to my furnace exhaust via tee or wye? And to protect this hot pipe, I would go ahead and run the 7" outer pipe up to the furnace pipe, about 6' away (i.e., none of the 4" pipe would be exposed). Is this a fire hazard or some other dangerous situation? Does my 25,000 BTU fireplace put out more exhaust heat than my 80,000 BTU furnace? They generally would not run at the same time. And if this is feasible, can I just use galvanzied steel stove pipe? Maybe I'm just an idiot, but I don't see what the problem is. I think it meets the intent - the combustion chamber is sealed, hot air is exhausted out of the house via the furnance exhaust system, and combustion air is drawn in from the garage. Would the fact that the exhaust and intake pipes will be different lengths affect how the fireplace burns? And if this is just an outright bad idea, anyone know where I can get 4" x 7" direct vent piping at a discount? Sorry for the long post. Happy Holidays. PS. This is not the first DV fireplace I've installed.