What does radiant heat require?
We are replacing our bathrooms and I’m considering bringing it up with the contractor to pull out the gas/forced air heating in those rooms and replace it with radiant heat in the floor, at least in the main one. The reason I’d like to do this is that there are four rooms all off that same branch of ductwork (via a giant splitter) and my daughters’ bedroom is freezing. We had an HVAC guy look at it several years ago (the ceiling has been open since!) and the configuration is such that the supply to her room cannot feasibly be improved – there are too many structural elements, furnace vents, etc in the way and the house is small enough that there’s no place to move that stuff. But I think (I may be wrong) that if we only have 2 rooms instead of 4 being heated and get rid of that giant splitter we will have better heat in their room.
If this sounds crazy, please tell me. I’d rather not force my contractor to look for a tactful way to tell me that I’m nuts.
If this isn’t crazy, then it becomes a question of feasibility. What would radiant heat to a 49 sq ft room require? If we subtract the floor under the bath and the sink then it is more like 25 sq ft. We have no space left on our electric service (60 amps) so I’m wondering if something like this would require a dedicated circuit, or could it go off the service that is already in the bathroom? If that is impossible, then we would need to use gas and a boiler. I’ve seen where some people are using the same boiler that they use for hot water – how big does this have to be? Would we need to up the gas supply for an additional boiler for this?
I realize that all this is easier to answer when you are the contractor standing there looking at it. However, I don’t even want to bring it into the discussion if it is completely impossible.
Thanks,
Amy
Replies
The contractor ought to be performing calculations to size the heat, though his experience may already tell him the answer.
One thing to know is that radiant heat is different than the electric tile warmers the people sometimes put in bathrooms. The tile warmers are low wattage and cannot heat the room. To heat the room you'd need a true radiant heater, such as a baseboard unit, or wall mounted unit.
Your 60 amp service is very small for a house, and it would be very unlikely if you add electric heat for even a couple of bathrooms.
You could install radiant floor heat, that is, heated tubing embedded in or directly underneath the floor that would be fed by a dedicated gas fired boiler, or could be, since the bathrooms are small rooms, be fed by your water heater. I think you'd be surprised at how expensive an option that would be.
Are your air registers balanced? Each room should have a damper in the duct. Check that the damper for the cold bedroom is fully open and the ones for the bathrooms and other rooms that are on the too-warm side are turned down at least half closed (45°) or could be even more.
Another alternative is insulation. If the insulation in the bedroom is skimpy, you could rip out the drywall and add more, possibly furring out the walls or using foam board to get another 2". That would save money, too, as opposed to adding more heat, which would cost money. If the window is really cheap, a new window could help some, too.
Oh well, it sounds like radiant won't be an option to help solve this problem. Thanks for the info. This contractor is not doing the heat, I was just hoping for a side benefit from having everything open to replace the plumbing.
I don't believe that there are dampers in the ducts after the splitter because they are buried behind drywall. The HVAC guy was surprised to find that giant splitter in the ceiling of the downstairs bath.
The bedroom is buried in the ground, which provides a level of insulation, and adding more insulation isn't something we will be doing at this time - the bathrooms are enough disruption and expense. We hope to be replacing the windows fairly soon. The thing is, this room is the same as the others - same windows, same level of insulation. The only difference is that this room is freezing cold and the others are nice and comfortable. We wanted the HVAC guy to up the size of the duct and provide a cold air return (those were his suggestions), but it turned out to be impossible.