I am working on a retrofit of a 1400 sq ft home. We sealed the home pretty tight using a variety of typical weatherization measures. The home now measures 0.1 Natural ACH, 2.1 ACH50, or 732 CFM50.

The house seems to be performing well, but we have discovered that the 300cfm range hood or the dryer are putting the home into a state of negative pressurization. All of the major appliances are fully sealed combustion, but it seems that the weak links are some hard to seal areas of the crawlspace vapor barrier. We suspect that this is leading to the high radon readings (7 to 9 pCi/L). We have been considering installing a radon fan below the vapor barrier, but it seems then we are just going to have dueling fans and will be using more energy than we would like (we have been trying to hit “Zero”). All the makeup air kits that I find that could be interlocked with the range hood have energy intensive electric resistance heaters to temper the makeup air.

We are looking for some other options to explore.

Thanks for your help,

– Ron