Radiant Heat Questions (sensor, thermostat, etc)

piscesgirlDecember 6, 2012

Looking at putting radiant heated floors into our very small master bathroom. Only need ~20 sq ft to cover an area that is ~36" x 82" in size. Have a few questions I am hoping someone can help with.

1) Mat coverage: We will have a vanity that is lifted 7" off the tiled floor on 4 legs. Can we have the radiant heat mat go under the feet, as that is where the typical toe kick would be and I don't want the area to be cold.

2) Thermostat: I have read that you these are interchangeable across brands (e.g. SunTouch mat with Honeywell thermostat) Is this accurate? What do I need to look for to be sure I am getting the appropriate thermostat to coordinate with my mat (volt, etc.). Any recommended or suggestions as to what to look for when shopping for thermostats?

3) Sensor: I have read on the boards about having a second sensor installed. Are they referring to an extra floor temperature sensor? Will we need an extra power lead as well? Is the sensor linked with the mat brand or the thermostat brand or neither? I am just curious since I am thinking of using different brands for mat and thermostat. I also don't see extra sensors sold for every brand.

4) Alarm: Each brand appears to have their own branded Loudmouth alarm monitor or something similar. Are these necessary? If so, are the brands interchangeable, since the price points vary a bit by brand.

5) Mat Wire spacing: I noticed Warming Systems brand spaces at 3". From what I can find NuHeat states between 1.5" -1.75", and other brands list 2.5" or don't state the spacing at all. Is there a noticable difference between spacing widths?

6) Brands: It appears that for mats, except for wire spacing, warranty and price...the brands all appear to be very similar. Anything I am missing? Is there something else I should be evaluating (electric use for example, although for a 20sqft mat I don't anticipate it being very high).

Based on the boards it appears most people have used NuHeat (most expensive) and SunTouch, with a few other brands like Warming Systems (least expensive) and Warmly Yours. Has anyone ever used the Laticrete mats? I haven't seen anyone mention them on the boards, but I figured I ask since they appear to be reasonably priced (but I don't see an extra sensor option).


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1) I would want the wire to go a bit under the vanity, like 4". I have heard that people can feel the change of temp from the wired area to the unwired areas. If the toes touch unwired areas they would feel cold floor.

2) I got the thermostat that was sold at the website where bought my wire, Warmyourfloors. The name on the box is "Warmyourfloor

3) I installed 2 sensors. One will be hooked up as directed and the other just tucked into the box awaiting the call, if ever needed.

4) I used a digital multimeter instead of the "loud mouth". I spent about $30 on it if I remember. Got it at Lowes. It can be used for other things too.

5) I used WarmWire system from SunTouch. It is not the mat system. It is spaced every 2.5" in my installation. There is a warning not to get the wires too close, so there is a minimum distance to maintain.

6) As mentioned above I got WarmWire 240v for my 35sf needs. I bought it from Warmyour Floor at www.warmyourfloor.com

This is how I figured my wire needs:

After subfloor fixed to the need for my slate, the ply was primed for the SLC that will go over the wire:

The wire was covered with a plastic lath that I got at The Tile Shop. This was to add some strength to the SLC, I don't know if it is working or not:)

2 Sensors leading out of the wire area, you can see them coming from the lower left over to the right toward the wall:

    Bookmark   December 6, 2012 at 3:48PM
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Here is the setup we're doing. We also have small bathroom and the coverage will be about 20 sq feet. Our shape is not straight rectangle so we've decided to do wires instead of mats. Yes, you can interchange mats/wires and thermostats between different manufacturers, it's the fact no manufacturer will admit.
We will be putting Cerazorb for thermal insulation, RPM mats (perfect for wires, you can google it), Suntouch Warmwire (simply because the length of their 20 sq ft package is within a few feet of what we need, Warming System's package for 20 sq ft was cheaper but lengthwise was much smaller). I've bought Watts Radiant Loud Mouth Monitor, Aube Floor Sensing Thermostat TH115-AF-120S and extra sensor (total of 2) on Ebay, all much cheaper than straight from manufacturer. The thermostat doesn't have built-in GFI, which is fine, we will connect it to existing GFI circuit. Your case might be different. We will placing wires 2" apart, I think 3" is too wide as many mats offer.
I think it's OK to put mats right under your feet at the vanity since it's raised, the rule is to keep it 2-4" from vanity if it's on a floor.
Thermostat: you can get any thermostat as long as it has a floor sensor.
Extra sensor is not necessary, but recommended in case 1 sensor fails. I would recommend getting extra sensor the same as original sensor that comes with thermostat.
Alarms can also be interchangeable, again not necessary but helpful.
The mats/wires do appear to be very similar. I'd recommend getting ones with good warranty and good customer service. I don't think Nuheat mats are significantly better than Warming Systems other than that may be they have more wires per mat.

    Bookmark   December 6, 2012 at 4:15PM
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Thanks eduring. Few questions:

2) Do you recall whcih thermostat you got and just curious as to what made you choose that particular one.

3) Regarding your sensors...these are floor temp sensors correct? Just want to make sure I am ordering the correct thing.

6) You mention you got a 240v for your 35sqft needs. I was under the impression that for small sqft needs that 120V would work just fine. Should I look at 240V instead? What is the advantage of 240V over 120V? Is it just electrical efficiency (i.e. lower electric bills)? Is there extra electrician costs associated with going with a 240V? Just evaluating whether we should go 120 or 240.

Do you mind me asking how long it took for you to install the cable and strap system? I am wondering how much longer it takes versus a mat install. Curious as to whether it is worth the minor difference in cost, which is ~$47-$65 (depending on whether I purchase the $18 mat install kit for SunTouch)

This post was edited by firsthome on Thu, Dec 6, 12 at 16:29

    Bookmark   December 6, 2012 at 4:28PM
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thanks elk2000!
So based on your message the sensor is paired with the thermostat? So I could get a laticrete mat and a suntouch thermostat with extra suntouch sensor (just as an example. Is that correct?

Thanks so much. you are right...the manufacturers don't hint at all that brands are interchangeable. Makes a huge difference in some cases.

I can get a 20sqft Laticrete mat for the same price as cable wires, so I am leaning toward the mat route. I just now need figure out what thermostat.

I have not clue about the GFI. I will have to ask our contractor what he is planning on doing. Our contractor quote was for labor only so I need to research what we want and order everything. It has been very educational to say the least. When we are ready to redo our hall bathroom this will all be a piece of cake...if I can be so lucky :)

    Bookmark   December 6, 2012 at 4:40PM
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elk2000, I saw your post listed here:

I am looking at Warming Systems and Heat Tech as well. Both include thermostats, but the Warming Systems thermostat is a non GFCI thermostat. Did you ever find out whether it OK to just connect it to already existing CFGI circuit or whether you need to install a dedicated line for floor installation?

    Bookmark   December 6, 2012 at 10:08PM
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I think you can get an extra sensor from a different manufacturer, but just to be on a safe side I would make sure that 2 sensors are exactly the same.
I see no reason not to pair Laticrete mat and Suntouch (or any other) thermostat. Many different brands are using same thermostat which is, I believe, Honeywell.
If you already have a dedicated GFI circuit then you may connect your thermostat to it. You just need to calculate the total wattage already used on that circuit plus the wattage of your floor. If you have about 20 sq ft, that's about 12-15 wt per sq foot, so your floor will be using about 300 watts. Your continuous wattage, 80%, allowed by the circuit will be either 1440 watts (for 15 A) or 1920 (for 20A). So, make some calculations and see if you do need or don't need an additional GFI breaker.

    Bookmark   December 6, 2012 at 11:35PM
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