Busy

07:01 Friday, 22 May 2026
Current Wx: Temp: 40.23°F Pressure: 1029hPa Humidity: 88% Wind: 2.53mph
Words: 463

Been a busy week. Heavy on the HVAC. The "conventional wisdom" is that I shouldn't run the air-to-water heat pump in reverse to cool the floors because of condensation. Everyone thinks a fan coil would be better, because it's built to handle condensation. But it's something that's blowing air, which means it's something to clean and you can't sit near it.

I've got two contractors that are going to try to put together quotes for a solution that doesn't involve a fan coil. The key is going to be the dehumidifier, and managing the dew point. I think that the worst risk is opening the sliding glass doors on a hot humid day when we've been actively cooling and having a bunch of moist air come in. Might get some condensation on the floor by the door, which would be a potential slip hazard. Maybe. Warm air rises. How quickly does it rise when it enters through the door?

In an effort to talk me out of it, one contractor was posing the scenario of having the windows open during the summer. I said that if the windows are open, it's nice out and we're not cooling the floor.

We have three months out of the year when we're, potentially, actively cooling; and a few days here and there that are outliers, like the other day when it was over 90*F here. In May. A week or so after it snowed. But with the thermal mass of an ICF house, we're not going to be cooling during those brief spikes of hot weather. The house just won't get that hot.

When it's more consistently hot, we're keeping the doors and windows closed, we'll cool the floor and manage the dew point.

People love their ducts and their blowing air. We'll have some of that of course, with the ERV and the dehumidifier. But those aren't the kind of high-velocity, high volume airflows that an air handler puts out.

It'd be a no-brainer in the southwest where the air is normally dry.

One contractor I called, who came highly recommended, told me air-to-water heat pumps don''t work in winter. He said he'd installed three and he replaced all of them with boilers. I asked him who the manufacturer was and he couldn't tell me. That told me all I needed to know. He said if I wasn't putting a propane boiler, he wasn't interested.

Well, neither was I.

It's troubling when everyone says you're making a mistake. But there's just not a lot of experience with hydronic cooling in an ICF home. Everybody is going on their experience with stick-framed houses with no thermal mass.

Anyway, we'll see what happens. Maybe I'll change my mind.

✍️ Reply by email