We are building a “fairly tight” house in Central NH. It will be 2×4 construction with BIBs insulation and 2 ” of polyiso foam on the exterior. We were planning on using a natural draft propane boiler for our heat, but we are now wondering if the negative pressure will cause problems. We were not planning on installing an HRV, but using bathroom fans on timers for ventilation. We are doing all the designing and general contracting for the house ourselves, and my husband is a plumber, so he will be doing the heating system (forced hot water). He is against using a sealed combustion boiler, because he really wants one that vents through the chimney ( I think I’ve found that some do, but not sure). From what I’ve been reading though, it seems like we really need to either need to have a sealed combustion boiler or an HRV. Is this correct? Are there any other options that I’m not thinking of? We really don’t know how tight the house will end up being, but I’d hate to have to either switch out our boiler or retrofit an HRV system a few months after finishing the house.