If you love radiant floors and want off gas or propane, an air-to-water heat pump is the obvious question. It makes warm water instead of warm air, and radiant slabs want exactly the kind of lukewarm water a heat pump makes best.
It is also one of the least understood systems in Ontario, with few experienced installers. Here is what it does, what it needs, and how to design it so it actually keeps up in January.
An outdoor heat pump pulls heat out of the air and puts it into water. That water goes through your radiant floors, panel radiators or fan coils, just like boiler water.
The lower the water temperature the system needs, the more efficient the heat pump runs. That is why radiant slabs and air-to-water are such a good match, and why old radiators that need very hot water are a poor one.
What water temperature does your floor need on the coldest day? The lower it is, the better the heat pump works. That comes from the heat loss and the radiant design together.
Room by room, at your design temperature. See CSA F280 heat loss.
Tube spacing and floor design that deliver the heat with the coolest water possible.
The heat pump’s real output in the cold, not its rating on a mild day.
An electric element or a boiler for the gap on the coldest days. See backup heat sizing.
Many systems use a buffer tank to keep the heat pump from short-cycling. The controls matter as much as the hardware.
Radiant does not move air. The house still needs an HRV, shown on the ventilation summary (RMVDS) for the permit.
The best match. Design the slab for low water temperatures from day one.
Small loads, steady demand. See ICF heat loss.
Replaces a propane or oil boiler on an existing radiant system, if the floors can work at lower temperatures.
A heated slab in a shop is an easy match.
Against an electric boiler, it uses a fraction of the electricity on most days, but costs more up front. Against geothermal, it is cheaper to install but less efficient on the coldest days. Against gas, it depends on your rates and your house.
The heat loss is where every one of those comparisons starts.
Thinking air-to-water? Send the drawings. We size the load and design the radiant for low water temperatures.
Get Free Quote →A heat pump that makes warm water instead of warm air. The water goes to radiant floors, panel radiators or fan coils, the same way boiler water would.
Cold-climate models keep working well below freezing, but their output drops as it gets colder, like any air-source heat pump. Most installs in Ontario have a backup: an electric element or a boiler. The heat loss decides how big the backup has to be.
Heat pumps are most efficient making lukewarm water, and radiant slabs need lukewarm water. Old cast-iron radiators that need very hot water are a much harder match.
With fan coils, yes. Cooling through a radiant floor is limited, because a cold floor can sweat in humid weather. Plan cooling as part of the design if you want it.
It is still a small part of the Ontario market, and it mixes heat pump work with hydronic work. A clear design helps a good installer price and build it right.
Check whether the specific model qualifies before you buy. Rebate programs list eligible equipment, and rules change. See the rebate guide.
Send your drawings. We calculate the heat loss and design the radiant system to run at the lowest water temperature possible, with backup sized to the gap.