Can I use tankless water heater solely for radiant floor heating in Onario?

[antonvk]

Good morning,

I live in southern Ontario. One bathroom in my house, while has forced air supply, doesn't get enough heat (it is the farthest room from the furnace, and it only has a small duct, because there is no space in the crawl space walls to get the main duct that far). The room is 200 sq feet, and the heat loss for this room is 6-12k BTU/h, depending on the calculator I use. I am considering installing a hydronic floor heating for this room only as a secondary heating source, and want to do a closed loop system. One of the options is to use a completely separate small water heater (tankless or with a tank), something that was designed with the space heating in mind.

Do regulations in Ontario allow using a water heater (not a boiler) only for space heating, if this is a secondary heating source?

 

[Sylvan]

When I did use a 30 gallon water heater to supply a small room with baseboard I used a 30 # Relief valve and set the automatic feeder to 12 PSI and the thermostat to control the circulator

I do not know if the local inspectors would have approved it as water heaters have only one safety device and that is the T&P

Boilers not only have operation controllers they have high limits, LWCO and a safety /relief valve /spill switches etc

 

[Sponsor]

 

[Taylorjm]

How do you plan on installing hydronic floor heating in an existing bathroom? If it was me, I'd use one of those small electric wall heaters that are like a flat panel against the wall. Safe to use and easy to install.

https://www.homedepot.com/p/Wexstar...ERCH=REC-_-pipsem-_-307665070-_-307665043-_-N

 

[antonvk]

@taylorjm, under the subfloor in the joist space, it is accessible from the crawl space underneath.

I want the floor, shower, bathtub, toilet to be warm as well, and these built-in items consume all the wall and baseboard space in this bathroom, so I literally have 2 feet of baseboard and no wall space at all. An electric water heater is an interesting option, but I heard that their recovery rate is insufficient for heater floor applications. What is your observation?

Besides, the idea of using an electric water heater raises another question: can it be electric heating wire in the joist space under the subfloor instead of PEX tubing? Probably also easier to install.

 

[Taylorjm]

@taylorjm, under the subfloor in the joist space, it is accessible from the crawl space underneath.

I want the floor, shower, bathtub, toilet to be warm as well, and these built-in items consume all the wall and baseboard space in this bathroom, so I literally have 2 feet of baseboard and no wall space at all. An electric water heater is an interesting option, but I heard that their recovery rate is insufficient for heater floor applications. What is your observation?

Besides, the idea of using an electric water heater raises another question: can it be electric heating wire in the joist space under the subfloor instead of PEX tubing? Probably also easier to install.

Maybe someone else has more experience in this field, but from what I've heard, adding pex under the wood floor, even if using the metal reflectors, doesn't work very well. Radiant floor heating works best when it's embedded in concrete and heats the mass of concrete and it continues to give off heat even when the water stops circulating. Not to mention the installation is a pain since you have to remove all the insulation, try and loop pex tubing around all the plumbing that's coming up through the floor and reinstall the insulation. I think your expecting too much from the pex tubing underneath the floor sheathing to make a difference in heating the room. Maybe if this was a large great room, you would have enough tubing to make a difference, but I don't think it would work in your case. I know lots of people that put down the electric coils embedded in the concrete and tiles on top and that works great at adding heat to the room and to the comfort level, but just running hot water through pex under the subfloor, I just don't think it's going to do what your thinking. Just my opinion.