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What products do you recommend for low watt radiant electric beneath tile?

rossn
rossn Member Posts: 59
edited February 2022 in Radiant Heating
Anyone have any low-watt radiant electric heating systems you are fond of?

I have a lot of hydronic radiant going into my remodel, and the below-grade bathrooms on uninsulated slab, I'm planning on electric radiant. Less for heating the room (there will be radiant ceilings and a towel warmer), and more for conditioning the chilly floor. Hence the 'low watt' need. I was planning to use Cerazorb insulation beneath it (R1.5).

Ideally, the thinner the better, and one that is free-form for running wires would work better than the pre-assembled mats.

if anyone has a better insulation option than the cerazorb, I'm also interested to hear about that, too.

Thanks!

Comments

  • PC7060
    PC7060 Member Posts: 963
    edited February 2022
    Schluter heat system over DITRA heat decoupling layer. Ditra heat has nubs the wire gets snapped into which simplifies installation.  


    rossn
  • hot_rod
    hot_rod Member Posts: 19,275
    The Sun Touch mats can get installed in a thin set, grooved plastic trowel application
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    rossn
  • btrem49
    btrem49 Member Posts: 2
    I have the plastic mesh type in my lower bathroom. I goes on directly below the thin set under the tile.. it is low voltage with a wall control.. It warms the tile and then the room. It is about 15 years plus and no issue whatever. Looks like a orange waffle snow fence but goes on the underlayment. No water and anything to break.. The tiles have take it just fine.. no cracks or issue.. warm on the feet.. The places it doesn't cover we don't walk on. My only heat in the room. In N.E that says it all. Home Depot or Lowes has similar. Vets discount and your set to go...
    rossn
  • rossn
    rossn Member Posts: 59
    All thanks so much.

    I think that for my situation, doing a cable that clips into the matte will allow me to not have gaps in my heating, given the shape of the room. Both Schluter and Sun Touch appear to have this.

    Since I am just looking to condition the floor (not heat the room), I was assuming that using a lower watt product (like 9w/sf) would be more efficient. But, maybe I am not thinking about that incorrectly, provided there is a tile temp sensor. In that case is it safe to assume using a 12w product will consume the same energy as the 9w product?
  • archibald tuttle
    archibald tuttle Member Posts: 1,033
    rossn said:

    All thanks so much.

    I think that for my situation, doing a cable that clips into the matte will allow me to not have gaps in my heating, given the shape of the room. Both Schluter and Sun Touch appear to have this.

    the prewired matts are actually pretty easy to shape around corners. you can cut the matt strategically and the heating wire is only one point of contact so you can turn 90 or 180 pretty easily. you can get the matts in varying lengths to provide enough cover even for odd shapes. i'm not knocking the independent wire with base approach but when you compare cost and availability. I didn't have to splice although I think it's possible. IIRC the splices might be thick enough you want a little divot in the subfloor but otherwise you prime it down with some thinset and then just go easy with notched trowel setting the tiles on top.
  • rossn
    rossn Member Posts: 59
    Thanks for that additional context... I will definitely take that into consideration and look into it further. Now, one advantage of the ditra-heat-duo is that it has an additional thermal break beneath, which is good in the situation of an uninsulated slab (would still have additional insulation beneath).

    Is there a situation by which concrete is poured over the matts or independent wires, if I had the depth?
  • archibald tuttle
    archibald tuttle Member Posts: 1,033
    i never would put on an uninsulated slab. i just did a bathroom on an uninsulated slab. added 1.5" xps foam and 3/4" pressure treated plywood, best (two thicenesses opposite grain) even better not to crack large tiles from motion. if you're piping from scratch you can allow for the floor height. in this case, bathroom was already piped into the slab so I used the flange with internal allen screws to tighten in place.

    https://www.zoro.com/oatey-toilet-flange-4-pvc-whiteblack-43539/i/G0333509/
  • heatexpert89
    heatexpert89 Member Posts: 1
    edited March 2022
    You would definitely want to insulate the slab or the heat will go downward regardless of the system you choose. STEP Warmfloor is a extra low-voltage (24V) product that is 3/64" thick and would work well in your application. Typically wattage is 4-6 watts per sqf.