# how to thermal heat switch



## gghrt000 (Jul 12, 2014)

while I was painting a while ago, I did not bother to remove or cover the thermal heat switch now bearing the fruit. Once all the job done half-painted those switches are an eyesore. I am wondering whether these are removable. I looked around no screws it looks like it might be removeable to stretching the side and bottom a bit. But before I do, I just wanted to ask around.

https://www.dropbox.com/s/winttl8onifog7p/IMG_20140712_175852.jpg
https://www.dropbox.com/s/winttl8onifog7p/IMG_20140712_175852.jpg


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## bud16415 (Jul 12, 2014)

Yep the cover snaps off. What you should have done was cover it with painters tape before you started. 


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## kok328 (Jul 12, 2014)

pop em' off and soak them in hot water.  the paint should come off with a little scrubbing.


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## gghrt000 (Jul 20, 2014)

ok i got them popped off. I also slid open the revolving know and what is behind was a main unit into which 5 wires 2red+2black and one ground wires plugged in. Yesterday went to homedepo and what they have is completely different shapes and sizes than mine. Mine is quite old revolving knob switch probably original installed unit when it is built back in 1990. The ones in store was much more advanced programmable units. I am not sure those will work. I will do some research on this one. If I find a suitable unit in terms of wiring and approximate size, I would much rather replace the old unit as it is looking very dirty now. 
THis is what i see for wiring harness diagram behind the plastic casing (also pic included)


NON-INDUCTIVE RATING 
D22 125/250/277 VAC
22AMPS DOUBLE POLE
WIRING DIAGRAM

2 red wire going  from STAT to LINE
2 black wire going from STAT to LOAD


Thanks,


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## gghrt000 (Jul 20, 2014)

actually i find a bunch of them in the homedepot. the ones resembling mine with rectangle shapes has a 120/240 rating instead of 125/250/277VAC with the current one. Wonder if this make a big difference. 
http://www.homedepot.com/p/Cadet-Do...-White-T410B-W/202502063?N=5yc1vZc4ltZ1z135q8


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## nealtw (Jul 20, 2014)

That will work, just make sure it is double pole when you pick it up.


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## Wuzzat? (Jul 21, 2014)

gghrt000 said:


> NON-INDUCTIVE RATING


Which implies that the load is resistive - no coils, no motors, no tungsten filaments, all of which wear out switch contacts rapidly.

At 240 v, 22A gives you a max load of 5300w.  If your heater nameplate shows less watts you can go smaller on the switch and maybe save some bucks.  16A, 3800w seems to be next smaller choice.


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## gghrt000 (Jul 21, 2014)

i see, i will have to take a look at the heater. there are two one in the living room and another in the bedroom. Since i live in a cali state, rarely need to use the heater, during winter I turn it on so much never even close to max. It is probably going to be ok then..


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## Wuzzat? (Jul 21, 2014)

Yes, intermittent use at below max heat = long switch life.


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## nealtw (Jul 21, 2014)

Check the size of the breakers

Yes, intermittent use at below max heat = long switch life.

Switch is either on or off, so max heat whenever it is on.

Breakers maybe a little light for the amount of amps because they are continues use and no big start like a motor.


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## Wuzzat? (Jul 21, 2014)

My bad.  Didn't look closely at dial markings.


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## nealtw (Jul 21, 2014)

I did get to read it before you pulled it.:rofl:


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## Wuzzat? (Jul 21, 2014)

nealtw said:


> I did get to read it before you pulled it.:rofl:


Yeah, I assumed it was 0 to 100% power using a bimetallic element, like a stove control.


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## nealtw (Jul 21, 2014)

Yeah, no, if you set it at 72 it may start at 70 and turn off at 73 but they are just on, off. Older stoves worked the same way
http://applianceassistant.com/Range-Stove-Repair/How-Electric-Ovens-Work.php


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## gghrt000 (Jul 22, 2014)

Ok I am just getting ready to install. I will look through later threads after installation . 
It appears from cover back diagram two red lines are from LINE and two black is to the LOAD which is the actual heater. Does it matter if either two of the blacks are switched or two red lines for LINES are switched???

On the newer one, there are marking L1 L2 T1 T2 however no such markings whatsoever anywhere on old one. Only thing I can see on old one is red/black color coding. This should be a last help! Thanks,


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## nealtw (Jul 22, 2014)

Usually 1 red and 1 black come from the breaker and the same go to the heater. With some kind of continuity tester you can find which is the heater. A meter a test liught , make something out of a flash light.


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## Wuzzat? (Jul 22, 2014)

gghrt000 said:


> two red lines
> two black
> either two of the blacks are switched or two red lines for LINES are switched???


As many times as I have treated the same color wires the same, by now certainly I would have had some bad outcomes if the same color meant different things.


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## nealtw (Jul 22, 2014)

[ame]https://www.youtube.com/watch?v=KtJMpJGGLJo[/ame]


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## gghrt000 (Aug 4, 2014)

thanks nealtw, watched the video it gave me an important reminder to turn off the fuse, i was going to do it on live wire!! 
After looking at video i also found important difference between old and new one.
On old one, both red ones are going to LINE and two black are going to THERMOSTAT.
I can see because two reds are connected to black and white one lumped together from the wall. 
That is also what the diagram on the old thermostat's cap shows:






Now NEW one completely different and is similar to video, one black (L1) and one red (L2) one going to LINE and other black (T1)  and red (T2) one going to LOAD. I can see it is marked on the unit and this is how I am going to connect the unit: 

L2 - red (line) - white from LINE
L1 - black  (line) - black from LINE

T1 - red (load, thermostat) - white from LOAD
T2 - black (load, thermostat) - black from LOAD.


i hope this will not blow up the building..!!


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## nealtw (Aug 4, 2014)

Have you been able to figure which pair is line and which is load?


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## gghrt000 (Aug 4, 2014)

i think so, it does not identify on the wall itself but looking at the diagram inside the cap, whateever two wires from one of the wall holes that are connected to two RED  wires must be the LINE...(if you look at the pic above with the old thermostat cover)
If i had a voltmeter I'd rather measure:
between two LINE wires, there should be a voltage difference and between two LOAD wires there is none? 
There is no other way around it.


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## nealtw (Aug 4, 2014)

Usually line will be 1 red and 1 black and load will be 1 red and 1 black, they should come into the box paired like that. With the breakers turned off there is no continuity between the 2 load line wire and there is between the load wires. You can make a tester out of a flash light. If you have an old style flash light that the back end comes off hold one wire to the battery and the other to the metal strip that goes to the switch and turn on the flashlight. When the lightcomes on, you have continuity and you have found the load pair.


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## gghrt000 (Sep 14, 2014)

Guys i finally installed all 3 units into my wall, and tested 2 of them working since one of the heater is shot. I had to turn all the way you to 75 degrees for the heater to start heading up. I presume it is because hot day?? That let me to believe perhaps it is aware of current ambient temperature?? Also I might need to touch on the wall around the visinity a bit as I have been scrubbing dragging the wires and stuff along the wall as I am working. Last of  all thanks giving me a invaluable info.


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