In-floor Heat

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  #1  
Old 02-01-08, 03:04 PM
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Angry In-floor Heat

Wow...has this project ever been a crazy process. I recently remodeled my lower level and hired most of the work out. My greatest area of difficulty has arisen from the in-floor heating system. It is a pretty large area and took all of two Easy Heat DFT 2215's. My electrician and I ran a fresh 30 amp 220 v circuit from the panel using some ungodly thick wire that was a real drag to pull through joists. So, here's the problem...the tile contractor took it upon himself to lay and pour over the heat kits (yup...a little out of the realm of his expertise) with the understanding my electrical contractor would handle the hook-ups. Sounds simple enough. The first problem was realized the day the electrician came to wire the two thermostats (one for each kit) into the new 240 volt line we pulled over. We realized that the tile setter laid the two temp sensors side-by-side in "zone 1". What to do? The floor was already finished and we waited 1.5 months before firing up the heat to give everything ample time to cure. We ended -up wiring the two thermostats separately as planned and each unit has its own temp sensor, unfortunately they're both located in the same zone. The system worked well for about the first week with both zones heating equally until "zone 2" started popping its GFCI. The manufacturer says that we probably should have run two dedicated circuits but he really din't know for certain. We all agree though that if the sensors indicate the same temp and calls for heat then both thermostats should send current at the same time and that alone shouldn't pop the GFCI on the stat. I'm planning on swaping the zone 2 thermostat out for a new one to check if it might be faulty. I doubt it is because of the temp sensor not being where it should be for that zone. I guess my question for anyone reading this is to figure out if anyone knows of a single thermostat capable of running two DFT 2215's - each of which draws 2,576 watts at 240 volt 10.7 amps and 21.6 ohms (x2). I'm at the point that I don't even care if it is a siple knob-turn dial versus the electronic display. Also, the current two thermostats I'm using are made by FloorStat and are model PB112-240GA (500650) capable of 240 VCA, 60 Hz, 15 amp, 3,600 watts and a 5 mA GFCI.

These in-floor heating systems are really great but I'm finding that nobody seems to know enough about them to offer any real advice.

Any advice or input is so welcomed you cannot believe it.

Thanks,
Cold feet in MN
 
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Old 02-01-08, 03:40 PM
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Originally Posted by briford View Post
the tile setter laid the two temp sensors side-by-side in "zone 1". What to do?
Break out a tile in the center of zone two and a channel of grout. Install another temp sensor (or two) in the zone two location and reinstall the tile and grout.

until "zone 2" started popping its GFCI.
Have you measured the resistance in the cable? Is it possible the cable was damaged during installation? Does the GFCI trip right away or only after some time?

I'm planning on swaping the zone 2 thermostat out for a new one to check if it might be faulty.
That would be my next recommendation. You can even use known-good t-stat #1 to avoid buying a new one.

I doubt it is because of the temp sensor not being where it should be for that zone.
Unless perhaps the second heating cable was overheated and damaged because the thermostat wasn't there. I think this is unlikely, but it's possible.

anyone knows of a single thermostat capable of running two DFT 2215's
I think these t-stats are supposed to come from the manufacturer; they aren't general-purpose interchangeable from different companies. Did you check with the FloorStat folks to see if they have an adequate model?
 
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Old 02-01-08, 04:18 PM
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Originally Posted by ibpooks View Post
Break out a tile in the center of zone two and a channel of grout. Install another temp sensor (or two) in the zone two location and reinstall the tile and grout.

I know that this may have to be done...I'm just trying to skin the cat in as many other ways as possible - and I guess I'm not 100% convinced that this must be done.


Have you measured the resistance in the cable? Is it possible the cable was damaged during installation? Does the GFCI trip right away or only after some time?
The resistance is good - it requires 21.6 ohms and both zones came in right on the money. Sometimes zone two runs for a few days and warms the floor before triping - no rhyme or reason.


That would be my next recommendation. You can even use known-good t-stat #1 to avoid buying a new one.
Yes, I've thought about this too - I would hate to disturb the perfectly good one. I did switch the LCD control panels from one to the other and zone 2 was still poping. It may be in the base unit inside the receptacle, so yes, I should switch the bases out.



Unless perhaps the second heating cable was overheated and damaged because the thermostat wasn't there. I think this is unlikely, but it's possible.
I agree that it is possible and I pay close attention to the temps when in use. Zone 2 has never been hotter than zone 1 (85 degress).


I think these t-stats are supposed to come from the manufacturer; they aren't general-purpose interchangeable from different companies. Did you check with the FloorStat folks to see if they have an adequate model?
I did speak with one of the engineers (probably a janitor) and he said I can use any stat I wish as long as it conforms to the specs of the DFT 2215.

Thanks for your insight Ben - we'll see what happens.
 
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Old 02-01-08, 05:01 PM
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Originally Posted by briford View Post
My electrician and I ran a fresh 30 amp 220 v circuit ...
Using the 80% safety factor, that gives you 24 amps available constantly and you need 22.22 ... and I will show you that number in a minute.

Originally Posted by briford View Post
...the tile contractor took it upon himself to lay and pour over the heat kits ...
... tile setter laid the two temp sensors side-by-side in "zone 1".
A great reason for DIYing whenever possible! And whenever I simply *must* hire someone, I stand nearby and watch every move so I can more easily troubleshoot the work later.

Originally Posted by briford View Post
The system worked well for about the first week with both zones heating equally until "zone 2" started popping its GFCI.
Assuming your electrician has checked to be sure the heating wire is still open to ground, you might need a different-sized GFCI. I do not know the possible values at the moment, but not all thermostats have the same GFCI rating and some of them have no GFCI at all (and the GFCI is to be installed somewhere else in the circuit).

Originally Posted by briford View Post
The manufacturer says that we probably should have run two dedicated circuits but he really din't know for certain.
There are a *lot* of things those folks do not know for certain other than to point off in another direction!

Originally Posted by briford View Post
We all agree though that if the sensors indicate the same temp and calls for heat then both thermostats should send current at the same time and that alone shouldn't pop the GFCI on the stat.
Correct.

Originally Posted by briford View Post
I guess my question for anyone reading this is to figure out if anyone knows of a single thermostat capable of running two DFT 2215's - each of which draws 2,576 watts at 240 volt 10.7 amps and 21.6 ohms (x2).
240 volts and 21.6 ohms actually come out to 2667 watts and 11.11 amps, and you can see that for yourself here:
http://www.angelfire.com/pa/baconbacon/page2.html

Altogether, your two matts can draw over 5200 watts at full voltage and I do not know of any thermostat that can handle over 4000 (even though a linked system can). But if you decide or need to replace the thermostats while working on the GFCI problem, you can learn a little more about them here:
http://www.aubetech.com/products/lis...amille=1&app=6

Originally Posted by briford View Post
These in-floor heating systems are really great but I'm finding that nobody seems to know enough about them to offer any real advice.
Yes, and the ones who *think* they know ...

Ah, never mind.

I hope some of this might help you get things worked out.
 
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Old 05-01-08, 05:47 PM
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Gfci Trip Trip Trip Update 5/1/08

My quest continues! Here's what's happened so far, but first-off I'd like to thank everyone for their input. I appreciate your thought and willingness to sink your teeth into someone elses debacle.

Ultimately, I've learned three things - 1) make sure the installer installs a temp sensors in ALL zones, not just one without a relay. And 2) run dedicated circuits to each system or zone. My guy ran a 240V 30 AMP single to run both units drawing a total of 22.22 AMPS. AND 3) Very few people have any clue how these systems work! Still too new to the market I suppose.

I swapped out the thermostats and the same zone still trips. I did buy a new 500680 relay. I wish I could get my hands on the Aube with the 30 mA GFI as opposed to the 5 mA USA code standard, but I cannot find anyone willing to sell me one here in MN. Furthermore, the engineer says it will only last a few years before it starts to trip as well - assuming the problem is indeed buried in the floor.

Everyone agrees that both systems on one circuit is a no-no and could be what's triping the GFI somehow - even though I completely disconnected the good zone and tested the bad zone all by itself - and it still trips out.

The manufacturer had me check the ohms readings on both units - the good one and the bad one. They both still check out fine - 22.5 each.

He also had me spend a month of my life tracking down a Megohmmeter. Wow! What a nightmare. My electrician didn't have one...my HVAC guy let me borrow his but it didn't work because it didn't range low enough (used more to test motor windings etc.)...I finally BOUGHT the right one for $150 and am reading BOTH the GOOD and the BAD zones at .14 and .15. I'm waiting to hear back from the engineer at WarmTiles to find out what that means. I believe the insulation is good.

They're supposedly going to mail me some sort of testing equipment [to use with my electrician] to try and isolate a "leak" somewhere under the floor. That oughtta be good - Ding and Dong are back at at again.

I've talked with a few other electricians and one guy told me to remove the relay with the GFI and replace it with a basic two-pole relay for $30. He said that because the system is installed in a family room there is no need for the GFI. I'm tempted to follow his advice but I don't want to compromise the future integrity of the system down the road and furthermore the manufacturer doesn't think it would work anyhow.

This is really mind blowing for me to have to go through all of these steps to get this figured out. Next time I'll make sure there's only one person in charge - and it won't be me! Ugh.
 
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Old 05-01-08, 06:42 PM
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Please keep us posted, I'm very interested to hear how this comes out... have no useful suggestions, unfortunately.
 
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