Radiant floor heating..

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Warmsmeallup

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Location
Upstate, NY
We install electric radiant, and that's all we do. You can use a 4" box and it would give you lots of room to play but we use single gang deep boxes and they work fine if you work clean. All the line voltage systems require a GFI tstat. The low voltage systems use the same tstat as the Nuheat systems use (Honeywell) but with no GFI.

The most important part is being sure that you do or have done a Heat Loss Calculation for the space you're heating. A "floor warming system" that fits a 10 x 10 area may not be enough heat (in watts psf) for the space. The Heat Loss Calc will tell you what is being lost naturally and then you install a system that far surpasses that number. We use 50% higher as a standard. i.e. if the space looses 5000btu's of heat an hour, install a system that produces 7500 or greater. This is done by spacing the elements closer together or, in Nuheats case, ordering the mat that meets the load. Though that would be a special order.

You could also use a low voltage cable system that meets the requiremenst and space the cable accordingly.

Personally speaking, we never install a line voltage system as primary heat. The line voltage element, by it's very design, will stop functioning "at some point". And as mentioned, I wouldn't want to be the guy who installed one that went bad before the warranty period is up and have to prove it was the element. That is relatively impossible to do. The mfr wants the element back to view what went wrong. Go ahead, take the floor up and remove the element without damaging it! (Do you have a week and very small archeologists chisel?? :thumbsdown:)

So, we install low voltage when it's primary heat or we don't install it. The low voltage element is a single #14thhn wire that uses the rating of the wire to create the resistance heat. If you don't over amp it, it doesn't burn out. Unless someone damages the element on install, you may have to replace a transformer or tstat in 10 years but that's the worst. We have never had an element go bad and the mfr hasn't either for 28 years. They also have another bronze screen element that can be installed directly under hardwood. Nail through it, no problem! But that's another thread.

Heat loss calculation!!!

One last thing; install 2 floor sensors and don't connect one. If one goes bad, you have a backup without having to tear up an area to replace it. They are nothing more than thermisters. Thermisters go bad too!
 
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PetrosA

Senior Member
Warmsmeallup, I'm intrigued by the low voltage floor heating system. I found heatizon.com, although I'm not sure that's what you're referring to. The downside I see is you need a large area dedicated to mounting a pretty massive transformer and controls, plus (in the heatizon scenario) #2 CU "cold leads." Based on that, I'm guessing the material costs are probably about double that of what I usually install. Any thoughts on how the systems are to install from a practical standpoint? How much "tech" room do you need for a 8x12 (heated area) bathroom floor to mount the gear and where are you usually mounting it? Do they have a kit that installs in a wall cavity?
 

svh19044

Senior Member
Location
Philly Suburbs
I talked to a contractor that specs the warmly yours floor heat, and they DO cover labor and material for floor if there is a problem. It's a 25 year warranty.

You really are making an issue out of a non issue in terms of your concern over failure. I still don't know if I would want it as my primary heat source though, as I have always just considered it supplemental.
 
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PetrosA

Senior Member
I talked to a contractor that specs the warmly yours floor heat, and they DO cover labor and material for floor if there is a problem. It's a 25 year warranty.

You really are making an issue out of a non issue in terms of your concern over failure. I still don't know if I would want it as my primary heat source though, as I have always just considered it supplemental.

I agree about treating it as supplemental, but there are customers who want it... Another potential problem could be if you don't have enough floor space to heat a given area (high ceilings, lots of windows, etc) at the minimum spacing and/or without heating the floor to 130 degrees ;)
 

renosteinke

Senior Member
Location
NE Arkansas
I note that NuHeat is positively anal in their instructions as to megger teating the mats at multiple points during the installation, and doccumenting the readings.

I can understand their point .... they want to guarantee their quality product, but they're also well aware of all the things that can damage the cable during installation. Ever look at a well-used trowell? Those things can develop razor-sharp edges with use. The tiles themselves can be heavy and have sharp edges - especially the nicer marble ones.

The whole point of the megger log is to identify exactly who ruined the mat, and to make them pay to fix it at the cheapest possible opportunity in the job. NuHeat wants you to discover the mat is 'bad out of the box' long before it has the final tile set atop it.

I really like the alarms for the mats during the job. They remove a lot of doubt.

How will it last, over time? While you can visit the Middle East and find tile floors from the time of Solomon, the simple fact is that most tile floors last only ten years or so .... only until the house is remodeled on a whim. I've seen folks completely redo the baths and kitchens in brand new, never occupied homes. Go figure.

What if the heat fails? Well, bathrooms are usually somewhat sheltered, with only one 'outside' wall. It's pretty easy to add a heat lamp or heating vent fan to the room. Plus, all that hot water in the shower tends to warm the room up.

Planning, in advance, for baseboard heat is a good idea.
 

Warmsmeallup

Member
Location
Upstate, NY
Warmsmeallup, I'm intrigued by the low voltage floor heating system. I found heatizon.com, although I'm not sure that's what you're referring to. The downside I see is you need a large area dedicated to mounting a pretty massive transformer and controls, plus (in the heatizon scenario) #2 CU "cold leads." Based on that, I'm guessing the material costs are probably about double that of what I usually install. Any thoughts on how the systems are to install from a practical standpoint? How much "tech" room do you need for a 8x12 (heated area) bathroom floor to mount the gear and where are you usually mounting it? Do they have a kit that installs in a wall cavity?

Yes, Heatizon is the manufacturer and they have kits for smaller areas (up to 110sf in a mortar, self leveling or concrete) that uses an 8" square box for the transformer and fuse. They run about 1/3rd more than line voltage, except against custom Nuheat systems. For larger systems (greater than 110sf or so), the control box is 17"w x 12"h x 9"d designed to mount directly to 16" o.c. studs and has it's own 30a breaker when used for interior or roof de-icing systems. The same dims match the controls for snow melting in the ground but no breaker. The #2 thhn are the "cold leads" that splice to the #10 or Zmesh heating elements. Though, after personal experiences, I would have found a different term for them...like..."warm leads" or..."cold leads until insulated" because they certainly are not cold when running! hmmm...:?

I agree, they are not inexpensive systems to sell. Most, if not all of our work is on high end homes or, where snow melting is being sold, how much damage came before us. It is my feeling that it is a true 25 year warranty though. Technically, the element isn't being worn out in its use and functioning. All the line voltage elements are. So they have to have a life span. Again, back to my explanation of the warranty; line voltage has to be proven that it was the element that went bad. HOW?? Dig it out of the floor without damaging it? Good luck there. And, as previously mentioned, if you megger the wire upon arrival, while being installed and after it's installed, it is their contention that it's not the element that went bad. But wait, if you did your job and meggered it all the way through, and 3 months down the line after the HO moves in it stops working, how could it NOT be the element? Or, let's say we installed the system, tested it, worked great when we left but then the tile guys come in...you can get a repair kit for the line voltage or, in Nuheats case you have to ay to bring in their repair guy, once repaired, you lose the warranty.

The low voltage elements don't "go bad". If the element is cut or nicked while being installed and "goes bad" before or after being covered, it can be tic traced and butt spliced back together. We've dome it by removing one 12" tile. Also, you can't damage the zmesh by nicking it! It's a screen so it already has holes in it. If you tear or rip the screen tripping over it on the floor, they have a splice repair kit. Both repairs maintain the 25 year warranty.

The cable system (they call it Tuff Cable) uses a #14thhn for small areas and #10thhn wire as an element for larger areas interior or for snow melting. The bronze screen element comes in two widths (9 + 12" wide) and is called Zmesh. It can be installed under any type of wood, floating floor, carpet or tile. Nail through it all you want. As long as you don't contact any other metal, it fine. Though I'm not as happy with Zmesh under tile. The transformers range in size from .5kVA up to 6kVA. The

Bringing back up the "Heat Loss Calculation", either can and we have installed as primary heat. As long as you know the perameters, the numbers don't lie.
 

B4T

Senior Member
I talked the customer into getting a kick heater.. the water lines are already there.. :thumbsup:

Sure.. people always say don't worry about it .. but EVERYTHING we install breaks down sooner or later..

The conductors will last (100)+ years.. but not the parts it controls..

Better for the plumber to explain to the HO why they have cold feet.. :D

Some of you know how my luck with computers runs.. it has a lasting effect.. :eek:hmy::rotflmao:
 
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