radiant heat and ditra underlayment

RonNE

anyone have experience with using Ditra as an underlayment for a tile floor and a staple up. Can't seem to get anything above 65-70 degrees on the floor and that is with 140-160 temperature. Seems like one room ( masterbath ) will need additional heat. Rest of tile floor not quite so bad, bathroom on north corner and usually quite a stiff wind. Did not factor in anything for Ditra, way too late now.

Dan_60

Ditra

I used Ditra with my radiant system and now wih that I had put tile throughout the whole house, works great. Granted, I place my tubing on top of the floor with 7 " spacers and not staple-up but I don't think that would effect things that much.

JohnNY3

Did

Did you insulate under the floor?

Some recommend a minimum of R30 under the floor. Others say 3x the insulating value of the floor coverings.

Unknown

ditra is not a significant barrier to heat transfer.

step one is figure your heat load
step two is figure whether or not your emitter is correct (plated, most likely, would be a good idea)
Step three is insulate properly.

were all 3 done?

TLynch

I've had my system running a couple years now. Underfloor with ThermoFin C plates, followed by sprayfoam insulation (Corbond), over an unheated garage. 3/4" advantech ply, Ditra and tile on top. The variable injection system rarely sends temps over 110 deg and it's very comfortable (upstate NY).

Can't say enough for plates and insulation.

Brian R

Another Ditra radiant job working just fine

DIY'er here...Remodeled & expanded our kitchen, has two distinct areas, breakfast nook has staple up with heavy plates, and main kitchen has 1.5" overpour light weight concrete. Both with Ditra, and porcelain tile throughout. Both under floor insulated R30. All running on VS injection with ODR. Max mixing temp set at 120°. Using Tekmar room thermostat with slab sensor in overpour area. Nook area is exposed wall, windward side of house. We don't notice any floor temp. difference (by feel only). I've never measured to actually find out if the two areas have differeing floor temps, but my wife would have certainly complained if she felt so . So, in my case, Ditra posed no problem in conducting radiant heat upward.

RonNE

more info

house is 2 years old, bathroom on own zone, 8x10, 12" walls( insulated block ), one run of 3/8 onix staple up, 00R, foil bubble wrap and R 19 under, warm basement. Like this from getgo just to busy to investigate, will hold temp okay when above 20 outside but less than that and we start dropping. Sparco mixer, monitor supply and return temps with digital thermometer, out at 160 and back about 145. Can't seem to come up with solution. At flow rate of .19 gpm supposed to have 80 degree floor, not even above 70, ever.
Questions, comments??, and does anyone know why we need to fill out this code below to post

hot_rod

could be a

low problem? Maybe a kinked tube. If you can, disconnect boths ends and see how it flows.

Or the mix valved plugged with crap, restricting flow? Rubber tube can do that sometimes.

Was it stapled tightly and every 6 inches? the "connection" to the floor is critical with rubber tube staple ups. Hopefully two runs per joist bay.?

hr

RonNE

yes I removed the insulation and foil this past weekend to be sure of good contact, added a couple of staples but not a real need. Have disconnected both ends in the past and blown them out with water and also with air pressure in both directions, seems fine. No kinks in hose not sure what flow should look like going through almost 200' of 3/8 tubing though. I did install it with a pex leader from the boiler, was a little short on onix, suppose I could cut out coupling to be sure nothing partially blocking. Looking for a flow meter I could put inline to check flow rate.
Supply temp leaving at 160 and returning at 145, only looking for .19 gpm to heat room. ??

Phil_17

constricted flow?

200 feet sounds like a long run for 3/8 tubing. I thought the rule of thumb was to keep within 250' with 1/2 and going from 1/2 to 3/8 more than quadruples your head losses, so it may take a pretty big pump to push enough BTU's thought there. What do you have for a pump on this loop?

What did the heat loss work out to be? Hopefully somebody else will check my math, but using .19 GPM I get 11.4 Gal per hour through that loop. Figuring about 8 lbs per gallon of water and 15 degrees delta T, I only get 1368 BTUH that you are delivering to the floor. with 80 sq ft of floor being heated that's only 17.1 BTUH/sq-ft. Everything would have to be really well insulated and tight for that to heat on a really cold day.

RonNE

the floor itself has one 160' run of 3/8 onix, and there are a pair of 1/2 pex leaders form the boiler room at 20'.
The house is built with styrofoam insulated blocks, it has 2" of foam inside and out with 6" of concrete. Running 160 supply and returning at 145 degrees.
Manual mixer and own thermostat. Let's say there is not enough tubing to keep heat loss, would'nt the floor still be warmer than 65 degrees? Would like to measure flow rate, this has a Taco 00R and all looks fine. Any ideas for a flow meter. Thanks

Unknown

run a 20 degree dt and your max output goes up to 23+ BTUs/sq ft.