Kitchen tile floor heating project

[PetrH]

I'm not sure which part of the installation you have issues with CX, the membrane or the mortar bed? Mapei AquaDefense is rated to go over mortar beds and all radiant heat substrates. Reinforced mortar beds are an industry standard for radiant heat up here in the great white north, though many builders pour 1.5" concrete because guys that can pull a good mortar deck are rare.

[cx]

My problem is with a 1" deck mud installation with hydronic tubes running through it, Peter. The only published method for deck mud and hydronic tubing requires the mud first cover the tubes and then a cleavage and a standard minimum of 1 1/4" of reinforced mud be placed over that.

Even when gypsum-based material is poured over hydronic tubing it must be a minimum of 3/4" thick above the top of the tubes. And a bonded membrane is required over that.

Maybe y'all's TTMAC allows what you're describing?

[Splinter]

First thing is countless radiant pro's take issue with that open system info page that pops up on every DIY'er's google search. Search deeper and you'll read about Legionnaires disease, early system component failure, mineral buildup, etc.

Next is staple up isnt very efficient for an under floor system. Even installing the cheapest aluminum plates you can find will be a big improvement... I like Uponor's Joist Trak for under floor systems, have it in my own house.

Any striping effect depends on the temperature you're running through the tubing, and how long it operates. A lower water temp and a dedicated thermostat for the room would help to keep a more evenly heated floor... Though you said this isnt the primary heat source right? A low temp on constant circulation would give an evenly heated floor.

Most of the horror stories you've read about wood over radiant are likely due to installer error, or poor design.


I somewhat agree with Petr's mud method... Around here it's quite common to see pex embedded in mud and tiled... I've removed them as thin as 3/4" with no visible damage to the tile layer. In the past, I've done 3/8" pex in 1.5" of mud with no membrane without issue. These days I ditra over the mud floor before adding the tile layer. I guess Kelly says it's not an approved method though...

[cx]

Kelly hasn't mentioned an approved method at all, Alex, best I can tell.

The 1 1/2" of mud over 3/8ths" inch pex wouldn't scare me much at all.

[Splinter]

The only published method for deck mud and hydronic tubing requires the mud first cover the tubes and then a cleavage and a standard minimum of 1 1/4" of reinforced mud be placed over that.

Sorry.. published.. approved... tomato, tomahto...

[Bea Tyler]

Alex, thanks for posting about the health hazards associated with open systems. It never came up in my searching for subfloor systems. It has made us re-think open vs closed, and I doubt very much we will install an open system. As far as aluminum plates, I do indeed plan on using them - ThermoFin looks like a great product, look at their Heat Transfer study, if interested.

http://radiantengineering.com/contact

Bea