Hydronic Radiant Heating

Well one of our big desires for the house was to have hydronic radiant floor heat instead of forced air. Flagstaff gets pretty cold in the winter; where we live now has forced air, which we've learned is an expensive way to heat a big house with 2 stories and the floors are always freezing cold because it's on a slab. So we decided to make sure we could have the in-floor heat in the house we're building. Andy says the future dog will love it! Plus we didn't leave any room for ducts when we designed the floor plan! Since Flagstaff doesn't get overly hot during the summer, we are not putting in air conditioning. Folks from Phoenix seem to feel they need to have air conditioning in their Flagstaff houses, but I'd say the majority of people don't have it. So that's another reason that we don't need ducts.

In the garage we have a small utility room that houses the boiler and domestic hot water tank. The future controls and equipment for the driveway snow melt system will eventually be housed here as well. The hot water from the boiler is pumped to several manifolds throughout the house which control the loops of water going to the different heating zones. The guest bedroom, office and jack and jill bathroom are on one loop. The great room, kitchen, laundry room and powder room are on a second loop. The master suite is one the third loop. The game room/shop downstairs is on the fourth loop (these tubes were put in when the garage slab was poured).

Ted nicely arranged and installed all of the equipment in the boiler room and the manifolds in the ceiling locations. Next Alan the plumber and his sons installed the 1/2" PEX tubing that takes the water to and from the manifolds to heat the rooms. The tubes are placed at ~12" on center. Near windows and doors, the tubes are run closer together to allow for extra heating in the drafty areas.The tubes are stapled to the sub-floor. Ted did a pressure test to make sure we didn't have any leaks.

 

Gypcrete, which is a lightweight concrete product, will be poured on top of the tubes to provide the large thermal mass to carry the heat throughout the room. The gypcrete and tubes add a total of 1.5" height above the subfloor (which the builder planned for with double sill plates so that our ceilings don't feel lower!) Apparently gypcrete is used often in commercial and multifamily construction as a sound barrier between floors. So maybe Andy's woodworking equipment downstairs won't be that loud upstairs!

Tile can be put down on top of the gypcrete, but hardwood is a little more challenging since you can't easily nail into the gypcrete. So for the great room and the bedrooms we had to put down strips of wood (called sleepers) in between the rows of tubing to have a place to nail the hardwood. We cut all of these boards to length and glued and screwed them down to the sub-floor. When the gypcrete is poured, it will be leveled to the top of these 2x2s so everything is flush. Hopefully we can still see the tops of the sleepers so that we know where to nail! We also plan to glue the hardwood floor so that we don't have problems with imperfect sleeper placement.

 

 

The gypcrete should go in on Monday!