Radiant Floor Heat

[HighHeat22]

I am renovating an 1800 sq ft ranch house that I will be moving into in the spring. I am debating putting in Carbon fiber matting radiant heat under my floors. I have torn out all the existing flooring and now would be the time to install the radiant heating under the new flooring. I have a friend who did this and swears by it. I have not seen it but he says this is his only heat source in northern Michigan for the last 3 winters.

I am still going to put in a woodstove for insurance. I will never give up my wood . My question is has anyone used this type of radiant floor heat and how does it work.

 

[jebatty]

The concept is attractive but I tend to stay away from any electric resistance heating except short term supplemental space heating because of the cost of electricity.

 

[woodgeek]

You should read some more about radiant heat plusses and minuses before you go ahead.

1. Electric resistance heat is expensive.
2. If your house is well insulated and airsealed, the floor temps needed to maintain can feel cool to the skin, not toasty warm.

Radiant heat had its heyday when houses were poorly insulated and drafty, and everyone had boilers for central heat. Then you needed a warm floor to pump enough BTUs into the space, and the space was often so uncomfortable (from cold walls and drafts) that the warm feet were welcome.

In a modern, well insulated house without drafts, the walls and ceiling are nearly the same temp as the air, and you can easily afford to bump the stat up a degree if you are feeling chilly.

When they are still installed, it is usually in a bathroom as a 'luxury' item.

 

[HighHeat22]

These are good points I appreciate your help. I will definitely look further into the costs. My friend keeps telling me his system is cheap to run and I have questioned this because the cost to run anything electric is usually expensive. I have calculated out the cost to install this system and its right around 2 thousand dollars. The house has an old boiler system that has seen better days. There is no current duck work in the house. I plan on putting in a wood stove for sure.

 

[peakbagger]

I think its important to separate hydronic radiant from electric radiant. Hydronic radiant is about the most efficient way to heat a house as the differential temperature between the house and supply temp can be real low, as low as 20 deg F. That makes hot water storage far more efficient. Electric radiant is generally used for spot applications like bathrooms although I have heard it used on superinsulated homes for backup heat. I am not a fan of that approach except in severe climates as a cold climate mini split is less costly to run,

Fundamentally electric resistance heat is the most expensive way to heat and in anything other than a superinsulated home its going to be costly. Electric power is a major political football and any global warming political solution is going to raise the cost of power in the long run. You are far better off spending the money you would have spent on the floor heat with having an energy audit done and tightening up the place. Since you have the flooring removed spend some time at the seam between the wall and the floor. In many cases there are significant drafts coming in from the gap between the deck and the walls. On many homes its worth cutting back the drywall to form a slot, cleaning well and then running a bead of foam caulking into the slot.

 

[Highbeam]

Fundamentally electric resistance heat is the most expensive way to heat and in anything other than a superinsulated home its going to be costly.

Meh, depending on fuel costs and electric costs this can be false. Before oil dropped in the last couple of years, electric resistance heat was the cheapest heat source available to me other than of course electric heat pumps. It's not about fundamentals but about current fuel costs in your area.

On many homes its worth cutting back the drywall to form a slot, cleaning well and then running a bead of foam caulking into the slot.

I too have my floors removed at the moment. This slot is accessible. Expanding foam would be a mess but maybe caulking?

 

[peakbagger]

Expanding foam doesn't need to be messy if you use a bulk applicator and a container of soapy water to smooth out the foam. Caulk is the next best option but tends to not be as resilient, Depending on the width of the slot you may want to use foam backer rod.

 

[semipro]

Expanding foam doesn't need to be messy if you use a bulk applicator and a container of soapy water to smooth out the foam.

I haven't heard of this. How does it work? I use a commercial applicator but the fresh bead is so fragile and sticky I can't imagine smoothing it.

 

[semipro]

Recent post pertinent to the tangent discussion on air sealing.
https://www.hearth.com/talk/threads/natures-blower-door-test.151171/

 

[peakbagger]

I guess I left too much out of the post. My assumption is that if the flooring is up and the bottom of the drywall is exposed that the trim boards are removed. With a commercial dispenser, the beads are fairly controllable and a soapy finger will allow some smoothing but given that the seam will be covered with the trim board, looks are not really important. I usually just fill it so it squeezes out and then trim it with a knife. Once the trim board is back on the seam is hidden.

 

[HighHeat22]

I already used the spray foam and it worked great. In fact I had to tear out at lot drywall and I filled all outer walls between the studs with 2 1/2 inch sheets of foam and sprayed the edges with spray foam. A good friend gave me 29 sheets of 4 x 8 foam sheets otherwise it probably would of been much more cost effective to spray the cavities with spray foam. What a difference this made.

I am going to have an energy audit done and see were I am at with heating. The mini split might be a better option. I appreciate all the good advise and I will update with what I decide to go with.