Radiant Floor Heating

“We have decided to put in radiant floor heating in our house we're rehabbing. Jon will be taking up all the wood floor, installing the radiant tubing, and then reinstalling the wood floors.

Does anyone have any experience with this project or recommendations?”

“Make sure you insulate under the tubes well. Otherwise you end up loosing a lot of heat to the basement or crawl space rather than the room you are trying to heat.

Other than that I don't know much.
last edited: 6/04/07 11:40:06 AM”

“People I know that have had it put in are very happy.”

“I'm planning on doing this, using solar thermal as the source. Instead of ripping up the floor do you have a crawl space or basement access? Or can you create crawl space access? It would make the job FAR less painful, unless the flooring itself is too far gone to restore and you are replacing it.

PEX is the way to go, there are kits you can order online that include the brackets. Like 'zac said, make sure you have good (R-26 minimum) insulation below the tubes, fully taped, etc. That's another reason doing the job from below is easier.

Thermal mass is key to getting good performance. When (if) you rip up the flooring, you want to seriously consider laying down cement board on top of the subflooring, or a layer of compacted sand. This will give you more even heat over time. However, you must be sure the structure can handle the extra weight!

Lots of sites online and magazines like Home Power describe the correct components, water storage sizing (if you go with solar thermal or a boiler as a source), PEX routing, etc.”

“Ruby, you are really one ambitious soul aren't you? Good luck with all your projects.”

“I installed floor heat last year. I have a full basement that was only 1/2 finished, so I demolished the remaining ceiling and installed 1/2" pex on 8" centers (staple-up)in the space between the joists that are 16" oc for the upstairs. They make insulation that fits between the joists just for this application to direct the heat up. All the floors upstairs are red oak. I added steel radiant panels for the basement heat to keep from messing with the concrete basement floor. I used a high efficency condensing boiler with zone pumps and added an indirect water heater for domestic hot water. It works extremely well - multiple zones so you can keep the bedrooms cooler. Very comfortable heat.”

“GARFUM! ! !

IT"S ME! STRAT!

Happy belated birfday, BTW!


WASSUUUP!”

“garfum reminded me - put "radiant barrier" (Reflectix is one brand) on top of the insulation to keep the most heat in. The insulation garfum mentioned probably has a radiant barrier on top.”

“Dude - wtf? Call me!”

“The insulation has a relective surface that faces the pipe - you leave a gap between the insulation and the pipe - to reflect as much of the radiant energy up as possible.”

“aight!”

“Here is a pic of the boiler set-up.
http://www.thebackpacker.com/pictures/pic/sgt27y.php”

“tech mentioned PEX radiant heating. I just replumbed my entire house with PEX (potable water type) and its amazing stuff, very user friendly. I'd look into it for sure.”

“I like a cold surface on my tootsies while I wander around making my morning coffee. Radiant heat and I have never gotten along. Many like it, though, so all the best.”

“I was looking at a site today that says one of the options is to use your water heater as opposed to a separate boiler. Any thoughts on that?


"Ruby, you are really one ambitious soul aren't you? Good luck with all your projects.”
hobbit
12:22:12 PM

Not ambitious as much as running out of money. We are living in my condo and rehabbing the house. But it's too expensive to do that any longer. So we are going to move in mid-construction and then do as much of the work ourself because unfortunately we are not made of money. We have a 1912 Chicago-style bungalow.”

“It is done frequenty with a domestic water heater. You just need a heater with enough capacity to provide the heat. My water heater wasn't nearly large enough. Water heaters are not usually high efficency either - although some are - the instantanious water heaters are kinda cool for that application - but may not be recommended by the manufacturer. It may shorten the life of a normal water heater.

The staple up or floor track systems require higher water temps than those imbedded in the concrete. My system calculations indicated a 135 degree water temp - but I kept the max boiler temp at 130 all winter and had no problems. Floor covering will also effect water temp. 130 - 140 is a good temp for a domestic water heater, but that will require a 90 (or so)degree rise in the winter - which may lead to the capacity problem.

What size an area are you considering heating?”

“I just noticed the the age of your house - some other things to watch out for are poorly insulated walls. You'll find more insulation between Mars and Jupiter than you'll find inside the walls of most houses built in that era. You max out the capacity of a heated floor at about 35BTU/sqft. Without good insulation that may not be enough. Also check for tarpaper or horsehair under the wood floor - it will cause a horrible smell if you don't remove it first.”

“We found that out already, Garfum. Jon discovered that not only was there no insulation behind the plaster, but when he tore off the plaster he discovered there were places where he could see the neighbor's yard through the cracks. It has all been sealed, insulated, and drywalled as well as new windows where needed. The difference in the temp in the house is already noticeable. It has stayed relatively cool on the hot days so far.”

“I know what you mean Ruby. Even though our place was built in 1986, when they started tear-off on our exterior (getting new siding and sheathing, with an extra layer of insulation) they discovered that any place there was 4" or less gap between the studs they didn't put any insulation, from foundation to roofline, about 18'. That's about 72 square feet of no insulation, and it happened 5 or 6 times. Kind of like having the entire end of my house uninsulated. No insulation under the floors - its there but there are so many gaps there might as well be none it was installed so poorly. 4 to 6 inches of insulation in the attic when there should be around 18 inches. No wonder my A/C couldn't keep up when it was over 90 outside!

When its all done I will have gone from R-13 to R-26 in the walls (and it was only R-13 where there was any insulation at all), and from maybe R-11 in the attic to around R-45. Then I'll tackle the floor insulation...

...but only after I've installed the radiant floor heating above it.

The walls are only 60% done and I haven't done any of the attic insulation yet and already I noticed a difference when it got up to 90 last week.
last edited: 6/05/07 8:19:42 AM”

“Some other thoughts on a water heater vs boiler - Not all areas allow a water heater to be used for space heating so check the local codes first. If you do use one, either dedicate it to only space heating or buy one with a seperate coil for the space heating loop - Bradford White makes a dual purpose water heater for that.”

“all the floors in korea are heated”

“We loved it. Maybe. wew're thinking Dani's constant asthma attacks in our old apartment might be due partially to the heating pipes. While cleaning it out we found several areas where mold was growing out (and up) along the baseboards. Her attacks subsided almost immediately after we moved. Of course, it was a basement apartment so maybe that was more conducive to mold growth than the warm ceramic floors???”

“All moved, BM?”

“Yes. besides our loss of a "near perfect" kitchen it's much nicer. Definitely a lot more ghetto, though. Some kids shot at me with a BB gun as I got on a bus the other day at New Jersey & 3rd NW. That was interesting. The only time I shot at anyone was in the woods, hidden, with full camo on. These kids these days, eh?

I expect full gentrification in 1-2yrs.”