Troubleshoot heated floor wiring

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Old 02-08-20, 07:58 PM
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Troubleshoot heated floor wiring

I have 4 areas in my new to me house that have heated tile. Only 2 of them work. I have verified the thermostats work as needed since they each send 120v to the load circuit when turned on. I also swapped the working thermostat plates from the working to non working rooms with same result. My problem is I pulled the panel from the wall and in my bathroom that doesnt work I found 2 different element leads with a blue and brown wire each. The way they are currently wired is the thermostat hot is hooked to a brown AND a blue wire, and the neutral is hooked to a brown and blue as well. I cant tell the brand of elements that I have but from what I researched it should be White load wire to the blue element wires and the black load wire to the brown wires.

So to double check my research I pulled out a working rooms thermostat and found even more confusion, 4 element leads and again blue/browns mixed to the hot and neutral wires AND 2 brown wires that have stripped ends not going to anything. As far as I knew this room was working 100% but now I wonder how they are supposed to be wired.

I will check the resistance in the non working bathroom to see if I can get a reading at all or if they are a broken circuit, the tag on the element leads just say 120v@50hz but not a value to test for.
 
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Old 02-08-20, 08:10 PM
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Welcome to the forums.

Strange tag...... 120v@50hz. We have 60hz power here. It's not really a problem it just tells us that these cables were probably supposed to be sold in area where 50hz power is used. That would also explain the brown and blue wiring which is not commonly used here in the States.

You'll need to check all four wires in an area. You need to determine the colors of the heating coils based on resistance. You should find that two of the wires are one loop and the other two are the other loop.

Based on the connections found..... you may find the two brown wires show resistance and are one loop while the two blues are the other loop. Be sure to mark the way they are currently connected.

As far as I know..... the colors don't mean much. There is no hot/neutral polarity.
 
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Old 02-08-20, 08:28 PM
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I am sorry I misread the tag, it says 120v 50/60hz so that was my mistake. being heating elements I didnt expect there to be a polarity but I thought it was odd to mismatch the wires.

I tested my non working bathroom elements (2) for continuity. I tried all 4 wires to eachother and only one pair didnt show an open and it was a blue/brown combo from the same element but the resistance was way high at 1600k so I think i am SOL on this room.

Now I need to figure out why I have loose wires in a room that does work.
 
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Old 02-08-20, 08:44 PM
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That resistance is way too high.
An approx value in a large room is under 200 ohms.
An approx value in a smaller room should be under 2k ohms.

I'm seeing conflicting information. White and black signifies a 120v system while brown and blue signify a 240v system. I don't remember brown and blue indicating high voltage.

You have four wires coming from the floor. Two should be power and two should be an in floor sensor.
Is the power tag just on one of the pairs ?
Is that the pair that is completely open ?
 
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Old 02-08-20, 09:10 PM
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So I tested a little more on the working room to get a little more info of how it should be working. Coming into the outlet there are 4 sheathed white wires, I assume each is a different element.. They each contain a blue and a brown wire, so there are 8 wires coming from the floor elements.
2 live White and black wires coming into the controller/thermostat. The controller has a relay inside that energizes the 2 black and white load wires going to the elements.
I tested each sheathed wire pair for resistance and the 4 sets of wires are open to eachother. However, I did find that there is continuity between pairs of same color wires. So one brown to brown is 40 ohms, the other brown to the remaining brown is 40 ohms. same thing with the blues. and yes there are 2 unrelated black wires that is the floor sensor, they work fine.

So now I am starting to understand why each black and white wires had both brown and blues connected to them. I wish I had a good way to upload a picture. The element wires have no markings at all, the tag was on the Honeywell thermostat controller wiring, I realized that as I untangled the 14 wires from the box, so no it wouldnt have resistance specs on it.

I dont know if this is any help at all but we did buy this home from a Russian lady that had family Russian contractors build the home for her outright, so it may not have been constructed in 07 exactly how standard contractors would build. Maybe thats why I have colors that are not standard in the US.
 
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Old 02-08-20, 09:25 PM
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I pulled the non working bathroom box apart again to see if it were the same.
2 sheathed white wires, each containing a brown and a blue for the elements
2 black for the floor sensor
an incoming black and white power supply to the thermostat
an outgoing black and white load from the thermostat to the elements.
I tried to see if it was the same as the working room and it is not, the brown to brown is open and so is the blue to blue. one of the pairs of blue/brown is open and the other still reads the same of 1600k between the blue and brown pair. I think this room is no good unfortunately.
 
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Old 02-08-20, 09:33 PM
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I would expect a white sheathed cable with a brown and blue wire in it would be a loop.
You are saying that is not the case that there is resistance between two browns and two blues .

These floor cables must be installed carefully and checked several times during installation to watch for problems. More than likely.... they were installed and never checked during the process.
 
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Old 02-08-20, 09:55 PM
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I also would expect the same but yes I for some reason have resistance between same colors of different sheaths. So yeah I wish I knew the brand/model to know what is correct. I hooked the working room set of wires back up so the resistance pairs are on a hot and a neutral wire and the floors heat up great so its wired correctly i guess. either that or I set a fire in my crawlspace
 
 

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