Using a Thermal Break for a basement heated floor - Recommendations from NuHeat
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Eurob
master tile and stone installer
If 1/4 is the maximum allowed for the thermal break , the maximum you will get is probably around R1 to R1.5 .
With those numbers , the Laticrete 170 -- 1/8 + thinset 254 or similar -- could also work . The170 has no R value attached to it , but I think it was close to R .9 or 1.0 .
Install the 170 with thin set -- 254 R works good , then skin it , heating wire , etc
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ShowerDude
Showers
loose wire is gonna need to be fastened to slab via tapcons ramset or similar , i like a thinset embedded mat over wedi .....i realize you like nuheat as do i just not the fastening sytem of the loose vire version.......but there are low profile mat systems that can be cut on site and esily manipulated... Laticrete just one of many.....
Vegas_sparky
Digital Billy
I'm getting ready set my floor now. I did 5mm Easymat on slab, heating wire, then SLC. I've been warned about SLC not working over the mat. Its been down for two weeks, and feels solid. I have a great control to measure temperature differential. As it stands there is a 3°F surface temp difference between the raw slab, and area with mat/SLC. When standing, or laying on the matted area it just doesn't feel as cold as a slab. There is a perceptible difference. You can lay on the prepped area and it doesn't suck the heat out of you. Im guessing thats because your body heat is only affected by the thermal mass of the SLC layer, and the mat is isolating the slab pretty well. Time will tell. Time to tile.
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Vegas_sparky
Digital Billy
Tile is set. I broke out the + spacers, and mixed together some Prolite and Versabond, cause it was in the garage. I'm a hack.
JohnfrWhipple
BATHROOM DESIGN & BUILD
The tile fairy is coming for you Vegas. And she can be mean......
Just saying.
On a side note I heard from a "Little Birdie" two days back that Nu-Heat is going to allow the use of Ditra Heat. The same "Little Birdie" said the reason Schluter specifies the Megger test is because the factory that makes the cables skips this step. Where Nu heat does this testing before the cables are sold.
Anyone else hear this?
This info was not told to me by anyone at NuHeat or Schluter but from a person who can sell me either. Who knows if he is right. Should not be that hard to find out. I bet Jim Knows or can ask at work.
Jim? Does the company making the heating wire for Schluter in fact not megger test the cables like Nu Heat does? If so why? Is it a cost reducing measure?
Just saying.
On a side note I heard from a "Little Birdie" two days back that Nu-Heat is going to allow the use of Ditra Heat. The same "Little Birdie" said the reason Schluter specifies the Megger test is because the factory that makes the cables skips this step. Where Nu heat does this testing before the cables are sold.
Anyone else hear this?
This info was not told to me by anyone at NuHeat or Schluter but from a person who can sell me either. Who knows if he is right. Should not be that hard to find out. I bet Jim Knows or can ask at work.
Jim? Does the company making the heating wire for Schluter in fact not megger test the cables like Nu Heat does? If so why? Is it a cost reducing measure?
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Vegas_sparky
Digital Billy
Why's the tile fairy coming for me? What did I do?
I had done brief testing of the master bath floor heat during construction. Two weeks ago I trimmed it out, and left it off when I came back to Vegas. The relay base was bad, and it didn't shut off. Wife called and said it was hot. After 5 hours the floor temp was 87°F. That's a warm floor. I swapped out the stat this past weekend with the DS bathroom, and it cycled correctly. 5 mins on the phone this morning, and a new stat is on the way. Good service like that is hard to find anymore.
I had done brief testing of the master bath floor heat during construction. Two weeks ago I trimmed it out, and left it off when I came back to Vegas. The relay base was bad, and it didn't shut off. Wife called and said it was hot. After 5 hours the floor temp was 87°F. That's a warm floor. I swapped out the stat this past weekend with the DS bathroom, and it cycled correctly. 5 mins on the phone this morning, and a new stat is on the way. Good service like that is hard to find anymore.
JohnfrWhipple
BATHROOM DESIGN & BUILD
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Jadnashua
Retired Defense Industry Engineer xxx
Why it's a good idea to use a megger with any floor warming system
- on the roll...this lets you get a reference point for YOUR device (they're not all the same) so you know what you started with
- after you install it into the mat...this verifies twisting and pulling it didn't do something to the wires
- after final installation...before hooking it up to the thermostat to verify you're still good to go while the thinset is still likely possible to remove a tile if required, but mostly for confidence you've completed the job well before proceeding.
Tell me, how would you verify you didn't do something to the heating wire during the install if you didn't test it. It's one thing to know it was delivered in good working order, it's totally another to know you didn't damage something during the install. And, by using your own megger, you have a good starting point...they are not all the same, and few come actually calibrated particularly well even when new, and who knows after they've been in service awhile. When was the last time you sent your electronic tool(s) to a shop to be calibrated? Probably never. So, a reading from the factory test may differ significantly from yours, thus, you get a reference first.
Most heating systems suggest you test it...personally, I think it should be more of a requirement, not a suggestion...a continuity test is one thing, but a nick in the insulation, and it could trip the GFCI, making the install useless...and, as the cement crystals grow over time, it may not happen immediately, so it's useful to know that the insulation is still intact.
This is all part of the philosophy held dear to Schluter...they are a very conservative company, and if you install things like they say with good workmanship, it works.
Schluter's installation instructions for DitraHeat are to use a megger three times:
- on the roll...this lets you get a reference point for YOUR device (they're not all the same) so you know what you started with
- after you install it into the mat...this verifies twisting and pulling it didn't do something to the wires
- after final installation...before hooking it up to the thermostat to verify you're still good to go while the thinset is still likely possible to remove a tile if required, but mostly for confidence you've completed the job well before proceeding.
Tell me, how would you verify you didn't do something to the heating wire during the install if you didn't test it. It's one thing to know it was delivered in good working order, it's totally another to know you didn't damage something during the install. And, by using your own megger, you have a good starting point...they are not all the same, and few come actually calibrated particularly well even when new, and who knows after they've been in service awhile. When was the last time you sent your electronic tool(s) to a shop to be calibrated? Probably never. So, a reading from the factory test may differ significantly from yours, thus, you get a reference first.
Most heating systems suggest you test it...personally, I think it should be more of a requirement, not a suggestion...a continuity test is one thing, but a nick in the insulation, and it could trip the GFCI, making the install useless...and, as the cement crystals grow over time, it may not happen immediately, so it's useful to know that the insulation is still intact.
This is all part of the philosophy held dear to Schluter...they are a very conservative company, and if you install things like they say with good workmanship, it works.
JohnfrWhipple
BATHROOM DESIGN & BUILD
You skirted the question with more cut and paste.
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Jadnashua
Retired Defense Industry Engineer xxx
Instead of being such a PITA, if you'd read their installation instructions (or take a class), you'd know that each roll comes with the factory value stamped on it from their megger test. See page 26 http://www.schluter.com/ditra-heat/media/DitraHeat-Handbook-2014.pdf otherwise, how could you record the factory value on the test sheet? Sounds like your fairy is more of a troll.
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Vegas_sparky
Digital Billy
Actually these were unopened bags that were not stored on the floor, you PITA. LOL
You need to be careful with terminology. A "megger" would refer to a Mega-ohm meter. This is quite different from a VOM (Volt-Ohm Meter) that you might have laying around. A decent "megger" goes from $500 up to several thousand dollars. Megger is also a company that builds mega-ohm meters and other devices.
The difference is that a standard VOM will tell you if the resistance is in range or if there are any shorts. A "megger" will test how good the insulation is by applying a high voltage and determining the resistance.
Any of the heating mats/cables have the same test procedure as the link that Jim posted. There is a factory resistance, a resistance straight out of the box, and a couple more measurements completed by the time you finish the install. It is no big deal and it should be done anyway even if a heating mat company didn't say you had to do it.
The difference is that a standard VOM will tell you if the resistance is in range or if there are any shorts. A "megger" will test how good the insulation is by applying a high voltage and determining the resistance.
Any of the heating mats/cables have the same test procedure as the link that Jim posted. There is a factory resistance, a resistance straight out of the box, and a couple more measurements completed by the time you finish the install. It is no big deal and it should be done anyway even if a heating mat company didn't say you had to do it.
Vegas_sparky
Digital Billy
They do require a 1KV meg test. The terminology they're using is correct.
There is an insulation test, but still doesn't look like they are on the same page. I'm not sure if John knows what a megger is as he recently asked about it and Jim seems more like he is talking the continuity tests (resistance of the mat). At any rate, most people installing the mat will not have their own mega-ohm meter, so it doesn't matter which you installed and whether it was measured at the factory if you couldn't accurately measure it yourself. That is why I'm trying to make sure that they are on the same page.
Jadnashua
Retired Defense Industry Engineer xxx
No, most people only do a resistance check, if that. The 'howler' that many people use is only a continutity test, and it certainly will tell you if you shorted something or have an open, but not if your insulation is damaged (but not currently touching anything to create a short circuit or an open), which is why they call out a megger. Most heating mat/wire manufacturers recommend you do this, but the only one I know of that requires it if you want the warranty, is Schluter. When you're dealing with a GFCI built-into the thermostat/control, there is no such thing as a little problem...it must be correct. And, while that test can be run with various voltage levels, they do list the specific requirements in the installation instructions. Some, by no means all, selling dealers have and will loan, or rent you one for your install. Schluter recommends that to them as a good thing to keep costs down, and help to ensure people actually do those tests. The things are reliable, lots of companies have made heating wire and mats for ages, Schluter does not make the wiring or the thermostat, they are made to their specs, though, for them. You usually do not have an issue, but why take the risk? The actual test is simple to perform and only takes moments (assuming you have or can borrow the tool). In some places, you need a building permit for the wiring, and some electricians have the tool, and those familiar with and helping to install floor warming, probably have the required testing tools.
Just like you should flood test your shower pan...you should use a megger on your floor warming to verify it is good to go. Yes, you could eliminate that step, and you may be fine, but the consequences of having it wrong can mean lots more work or a lot of dissatisfaction.
My first encounter with a megger was in the USArmy, where we used it to verify long data cables to radars and missile launchers. They've been around a long time, and are sometimes the only tool that can do the necessary job. You wouldn't expect your doctor to guess at your blood pressure by squeezing your arm or looking at the pulse in your neck...you expect him to have the tool required to do it correctly...same with installing floor wiring wires.
Just like you should flood test your shower pan...you should use a megger on your floor warming to verify it is good to go. Yes, you could eliminate that step, and you may be fine, but the consequences of having it wrong can mean lots more work or a lot of dissatisfaction.
My first encounter with a megger was in the USArmy, where we used it to verify long data cables to radars and missile launchers. They've been around a long time, and are sometimes the only tool that can do the necessary job. You wouldn't expect your doctor to guess at your blood pressure by squeezing your arm or looking at the pulse in your neck...you expect him to have the tool required to do it correctly...same with installing floor wiring wires.
Eurob
master tile and stone installer
The cost reducing measure is not from , not performing the test , but from quality of cables .
Maybe you should megger all the wiring in your house , John . LOL
I bet the spaghetti will benefit from it .
Jadnashua
Retired Defense Industry Engineer xxx
And, other than John's incorrect remark that the Schluter cables aren't tested in the factory, you know this how? Have you physically compared them? What tools did you use to determine that? Do you have the tools and knowledge to ascertain one type of insulation is different than another embedded in a mortar or slc or the qualities of the wire? I doubt it...that would require lots of expensive equipment, a laboratory, and a very good materials science background. I don't have access to that, I doubt you do, either. So, it sounds like an unfounded opinion, which you're free to express, but until it has some good foundation, should be taken just as that, an opinion.
Tell John he doesn't need to flood test his pans. Tell an installer of a floor warming system he doesn't have to test his installation. The majority of them will work...the goal should be to eliminate them all from failing. John would call someone who doesn't flood test a hack. Well, when it comes to installing floor warming, not testing it along the way falls into the same situation in my opinion. Schluter happens to feel the same way. It's no fun to have to tear out a finished install to find a problem, especially if it could have been resolved while it wouldn't cost much in time or money earlier on in the installation. Safety circuits (the GFCI) will disable the floor warming if it detects certain problems. The same things won't happen if your pan leaks. The costs to repair can be similar.
Eurob
master tile and stone installer
JohnfrWhipple
BATHROOM DESIGN & BUILD
Too Funny.
Jim gets so mad. I'm just asking because that is what a little birdie told me. I have not bought any Schluter heating cable.
I'll stick to Nu Heat.
After looking at the Ditra Heat product. Won't be using any of that either.
And then there is the issue about the sounds the thermostat makes. I heard they are noisy.
One, Two and Three Strikes
Oh and Jim - this is Pita... You are unsung the word wrong again.
Now you have gone and infected Vegas with your improper use of this delicious bread... lol
Jim gets so mad. I'm just asking because that is what a little birdie told me. I have not bought any Schluter heating cable.
I'll stick to Nu Heat.
After looking at the Ditra Heat product. Won't be using any of that either.
And then there is the issue about the sounds the thermostat makes. I heard they are noisy.
One, Two and Three Strikes
Oh and Jim - this is Pita... You are unsung the word wrong again.
Now you have gone and infected Vegas with your improper use of this delicious bread... lol
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