I bought a Modine Hot Dawg Garage heater. The only venting solution I have is to attach the vent from the heater to the main B-Vent for my furnace and water heater. I already did the calculation for the current B-vent to see if it can handle the additional BTU'S and it can. Running up through the house is 5in B-vent. The run from the heater to the main B-vent stack is around 5ft. My question is: Can i attach single wall vent pipe into the B-vent? If so How do I go about doing that? Thanks, Mike