Oh, GRM Collective, Aid Me With Underfloor Heating

During a recent remodel, we created a small new bathroom. Since we heat with wood and this bath is in the far corner of the house, heating will be an issue. (It already is to a small degree.)

The exposed floor area is only 8-9 sqft. I'd like to make something with an under-cabinet pump/heater and run the tubing as I replace the current floor.

There doesn't seem to be any DIY info on the 'Net that I can find. If it was as easy as I'm thinking, someone would have done it already.

What am I missing?

Eagerly waiting for Sandy to leave, Keith

I put radiant floor heat in my shop. There's several companies out there that have DYI kits. I assume you are wanting to do it all from scratch versus use one of those kits? I bought all the components from http://www.radiantec.com/index.php

You can get electric floor heat for bathrooms that's pretty simple to install, although it's mainly just to warm the floor so your bare feet don't get cold - it's not enough to really heat the room.

There's some design information for hot water infloor radiant heat on the Uponor Wirsbo website: http://www.uponor-usa.com/Header/Systems/Heating/Architect/Overview.aspx

It takes a while to heat up and cool down so it's not ideal for many areas of the country of projects. This makes me think that an on/off situation like you'd want in the bathroom wouldn't be the ideal set up.

You could circulate water from your water heater. Use a valve to throttle it for the desired floor temp. PEX pipe and some reflective material below the pipes with some insulation below that.

The circulation pump will also give you hot water quicker at your fixtures if you get them on the circulation loop. I would use a reverse return; just add the floor region to your loop after the fixtures.

carguy123 wrote: It takes a while to heat up and cool down so it's not ideal for many areas of the country of projects. This makes me think that an on/off situation like you'd want in the bathroom wouldn't be the ideal set up.

Yeah, what he said. Originally I was going to keep my shop at a lower temp and only turn up the heat if I was going to be out there all weekend. I bought some infra red heaters to use for those times when i was only going to be out there for a short while. However, I learned a couple things after installing it. One is that (and this might not apply as much to you) with the floor heated, you can be comfortable at a much lower temp. If I'm working out there, 65 F is too warm. I usually keep it at 60F and I can be comfortable wearing a T-shirt. No drafts, no forced air, and warm feet go a long way towards that. The other thing I learned is that my utility bills hardly went up when using it (I did plan ahead for this, and my shop is insulated much better than my house!), so I sold the infrared heaters and now just keep it the temp I want it to be all winter. But what carguy says is very true, it does take a while to heat up, so be aware of that.

In reply to RossD:

That's how my system is designed. It's really simple and effective.

I used an electric resistance wire under the tile in our bathroom and our basement floor. I will never put down a tile floor with out again.

bathroom http://www.lowes.com/pd_195282-29411-12000430LW_4294856527__?productId=3019308&Ns=p_product_avg_rating|1&pl=1&currentURL=%3FNs%3Dp_product_avg_rating%7C1&facetInfo=

basement http://www.ebay.com/itm/110-Sqft-120-V-Electric-Radiant-Floor-Heating-Mat-for-home-Bathroom-Kitchen-Tile-/230841424999?pt=LH_DefaultDomain_2&hash=item35bf389c67 i got a much bigger roll, did about 400sqft

In reply to jhaas:

Can that be installed under the sub-floor, like in the ceiling of the basement to heat the floor above?

bravenrace wrote: In reply to jhaas: Can that be installed under the sub-floor, like in the ceiling of the basement to heat the floor above?

no that stuff is made to bed directly into a layer of mortar below your tiles.

The electric stuff goes in the tile bed. I doubt it has enough power to push any heat through the subfloor.

You can run a 20 gallon water heater and a dedicated loop of radiant heat. It has to be self contained with no cross connection to potable water with an expansion tank. Setting the water heater to 125 degrees or less will be perfect. Anything hotter than that will dry out the wood. The PEX needs to be rated for heat(hepex) and not for potable water(aquapex) because of the oxygen barrier on the pipe. Set the water heater to maintain temp and use a circulator pump wired thru a relay and a thermostat. Total cost would be less than a grand in materials.

For quick room heating, honestly a heat lamp is probably your best and easiest choice.

Electric heat tape works great imbedded in teh tile mortar base, but takes a long time, and only warms the floor to the touch- it doesn't heat the room.

Tubing can be imbedded to circulate water, steam or hot air, but it's thickness must be accommodated and it will need a heat source.

There are also radiant heat plates which can be installed on the underside of the subfloor, but they will also need a heat source.

Thanks all, Now I have more to work with.

I had considered the "slow to heat up" aspect but figured a programable thermostat would take care of that most of the time.

dimarra wrote: Thanks all, Now I have more to work with. I had considered the "slow to heat up" aspect but figured a programable thermostat would take care of that most of the time.

There's also the "slow to cool down" effect. The room can end up being sweltering when it heats up outside. It's kinda like when you have a building that's heated & cooled with water. They can't quickly switch over so you end up with lots of the year when you don't have either.