1. The combustion air intake for the condensing furnace is not hooked up… usually the old fresh air duct (usually a 5″ flex duct running directly outside) dumps air into the room… the furnace then uses that air for combustion… from a safety standpoint, there’s nothing wrong with that, but from an efficiency standpoint it is dead wrong. A condensing furnace that is 90% efficient or better should draw its own air directly into the furnace and should then exhaust combustion gases directly out of the house through the other vent. A furnace that does not draw in its own fresh air is likely not condensing… which means that it is not getting the rated efficiency. If It’s rated as a 95% efficient furnace, it is likely only operating at 85% to 88% efficient. The solution is to install a dedicated fresh air intake… very easy and something the contractor should have done.

2. The Domestic Hot Water is a power vented water heater, and given that it is under 50,000 btuh (likely a 38,000 btuh burner) it does not require it’s own fresh combustion air intake. If the house was super tight, and there are concerns re: choking out the system, then a power direct vented water heater can be installed. This is the same as the power vented tank with the exception that it has its own fresh combustion air intake.

I hope this helps!

John