#1 We have condensing boilers in the US, but the intake/exhaust through the wall has a coaxial configuration: The combustion air comes in through the outer part of the coaxial pipe, and the exhaust goes out the center, so that combustion air is preheated by the exhaust. This also protects a combustable wall. When you have blowing snow, additional precautions have to be taken for blockage of combustion air port.
When you have condensing combustion, you have to watch for acids forming in combustion exhaust when you condense the H20 if the exhaust is too cold. Best to keep exhaust above 250F exiting the appliance.
Same applies to heat recovery of diesel engine exhaust heat. Things get nasty at relatively low exhaust temps. |