# Help solve an "argument" about a DPST thermostat for my ceiling heat?



## McClary’s Electrical (Feb 21, 2009)

Blind Frog said:


> My electrician buddy was admiring my new Honeywell LineVolt Pro 8000 (TL8230A1003) as we prepared to install it. This is a DPST model (two red/two black). I told him I would like to find similar models for my SPST units (One red & one black wire) for my smaller rooms. He said that since I got the thermostat at a great price, I should just do all the rooms with the same DPST model. He said I should simply pigtail both reds and both blacks (Line & Load) and then tie into the existing wiring. I told him this either could NOT be done or it would shorten the life span of the stat. He says I am an idiot. We have a pitcher & pizza riding on it.


Hes right.


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## Blind Frog (Aug 23, 2012)

AAaargh! Hey, McCLary, since this is a LARGE deluxe pizza at stake, I hope you don't mind if I hear this from a couple of others. (I have heard BOTH responses):thumbsup:

Thanks for the input, though...I THINK!!!


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## Hippie (May 12, 2011)

Blind Frog said:


> AAaargh! Hey, McCLary, since this is a LARGE deluxe pizza at stake, I hope you don't mind if I hear this from a couple of others. (I have heard BOTH responses):thumbsup:
> 
> Thanks for the input, though...I THINK!!!


Sorry, you will be buying that pizza


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## Shockdoc (Mar 4, 2010)

Ask him if he likes pepperoni on that pizza ?


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## Blind Frog (Aug 23, 2012)

This IS shocking! Knowing my pal, he will make me watch him eat it! One more vote for him & I will concede and buy the beer & pizza.....I guess!

Thanks all - so far!


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## nolabama (Oct 3, 2007)

Hope you like the same kinda beer. Lol.


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## Blind Frog (Aug 23, 2012)

Youfolks sure seem to be enjoying this!! OK...tell me this...theoretically, should the thermostat LAST LONGER when wired this way or is it better to break the legs and wire the good side in if the wired side ever goes bad at a later time?


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## Dennis Alwon (May 9, 2009)

Breaking both legs will not constitute a disconnect for the heaters and that is a requirement. You can add breaker locks to the breakers or you need to use DP thermostat and break both legs


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## Dennis Alwon (May 9, 2009)

BTW-- I want some of that pizza


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## Shockdoc (Mar 4, 2010)

Without breaking both legs you'll always have voltage present at the heater when off. Is it a violation I don't think so.


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## dronai (Apr 11, 2011)

This was a brilliant move to get a DIY question answered !!! :thumbsup:


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## Chris1971 (Dec 27, 2010)

dronai said:


> This was a brilliant move to get a DIY question answered !!! :thumbsup:


Agree.:thumbsup:


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## Blind Frog (Aug 23, 2012)

Thanks dronai! & chris1971. I will enjoy the pizza in YOUR honors!

Shockdoc - I agree. It is NOT a code violation. It DOES violate Honeywell, though, who claim it won't work this way. (Think MORE MONEY MORE MONEY!!) LOL


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## Cujo (Feb 4, 2012)

Blind Frog said:


> AAaargh! Hey, McCLary, since this is a LARGE deluxe pizza at stake, I hope you don't mind if I hear this from a couple of others. (I have heard BOTH responses):thumbsup:
> 
> Thanks for the input, though...I THINK!!!


I hope you like deluxe.


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## sprdave (Jan 12, 2012)

Just to clarify, are you guys being sarcastic?... I think Frog is on to something.... I'll look into it when I get a chance

Edit: I guess Im just ruining the fun


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## sprdave (Jan 12, 2012)

First question, is there:
1) a red and black for line, and a red and black for load? or
2) two reds for line, two blacks for load (or visa versa)

If 1) pigtailing both reds and both blacks together is not going to work. 

I remember when I installed some double pole thermostats there was certain way to wire a single pole load, it's not what you initially think.


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## wcord (Jan 23, 2011)

sprdave said:


> First question, is there:
> 1) a red and black for line, and a red and black for load? or
> 2) two reds for line, two blacks for load (or visa versa)
> 
> ...


Yes there is a certain way to use only one pole.
I am not familiar with the model discussed, but the simple Honeywell stats i do know.
One pole is a definite off switch so that when the stat is turned off, not thermostatic off but physically turned, the pole is open. When you turn to the temperature desired,the pole closes.
The other pole is controlled by the sensor in the stat. So when the stat calls, the circuit is made.

When we wire cottages, and the cottage will be shut down for the winter, if we use single pole stats, the heaters would come on at about 4 to 5 degrees C, even though the wall stat is turned all the way down. Only with a 2 pole stat is the unit truly off when turned all the way down.

So for the OP, you win the pizza. Your buddy's way of splicing the 2 poles together, would have made the heaters run without a room temperature control, as the one pole would be calling all the time


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## kbsparky (Sep 20, 2007)

If you want to use a double-pole thermostat in a single-pole application, wire the poles in series. Since the normal operation of the stat only breaks one side, this will ensure that the temperature of the room is properly controlled by the stat.

But, some of the newer models require 240 Volts input to operate its internal electronic mechanisms, and this method will not work in such instances.


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## wcord (Jan 23, 2011)

Dennis Alwon said:


> Breaking both legs will not constitute a disconnect for the heaters and that is a requirement. You can add breaker locks to the breakers or you need to use DP thermostat and break both legs


Here is a major difference in CEC and NEC, at least here in Manitoba.
We are allowed to install single pole stats on baseboard or fan heaters(at least in Residential). And we dont need breaker locks.


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## Dennis Alwon (May 9, 2009)

Shockdoc said:


> Without breaking both legs you'll always have voltage present at the heater when off. Is it a violation I don't think so.


I disagree--it can be a violation. Read my post above yours.



> 424.19 Disconnecting Means. Means shall be provided to
> simultaneously disconnect the heater, motor controller(s),
> and supplementary overcurrent protective device(s) of all
> fixed electric space-heating equipment from all ungrounded
> ...





> 424.20 Thermostatically Controlled Switching Devices.
> (A) Serving as Both Controllers and Disconnecting
> Means. Thermostatically controlled switching devices and
> combination thermostats and manually controlled switches
> ...


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## sprdave (Jan 12, 2012)

I was just recalling wiring double pole thermostats and the poles do NOT operate simultaneously like a switch/contactor. The one pole is an on/off, that opens when the thermostat is clicked to off. The other is thermostatically controlled like a single pole thermostat. So the poles had to be wired in series if wiring for single pole, if they were wired in parallel then it would just be on/off control. 

That was for a manual thermostat, the one OP has is electronic, which creates other potential problems with this... the thermostat isn't going to have a constant 240v supply for the electronics. When the contacts are open it will get 240v, but when they close it will see next to 0v. Without knowing more details on this thermostat, I can't really say if there is a way for it to work or not.

And the other problem is, the way OP is described, it sounds like they would take the line from the box and connect it to the two red wires, and connect the load to the two black wires...which is not going to work. That's just connecting the line to the two contacts on one switch/pole and the load to the two contacts on the other switch/pole.

So conclusion would be, I don't think there is any way for it to work, definitely not the way described in OP. (go ahead correct me) :boat:


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## Blind Frog (Aug 23, 2012)

sprdave - AHA!!! Now we are getting somewhere! I may not be buying pizza after all. Here is what I have: 

My wall box current has black, red, white, and copper wires coming in. The whites are pigtailed together and run out to the load. Copper is grounded. Neither touch the thermostat. The black box wire runs to black. The red box wire runs to red. It is normally open

The NEW thermostat (Honeywell) I am discussing looks like this:










So now.....I ask again - for the pizza - can this DPST thermostat safely be wired, to code, into the box (which is currently set up for SPST).

I never said this was an easy puzzle.


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## user4818 (Jan 15, 2009)

Blind Frog said:


> sprdave - AHA!!! Now we are getting somewhere! I may not be buying pizza after all. Here is what I have:
> 
> My wall box current has black, red, white, and copper wires coming in. The whites are pigtailed together and run out to the load. Copper is grounded. Neither touch the thermostat. The black box wire runs to black. The red box wire runs to red. It is normally open


You're clearly not an electrician.


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## user4818 (Jan 15, 2009)

wcord said:


> Here is a major difference in CEC and NEC, at least here in Manitoba.
> We are allowed to install single pole stats on baseboard or fan heaters(at least in Residential). And we dont need breaker locks.


I like that code rule. :thumbsup:


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## wcord (Jan 23, 2011)

Blind Frog said:


> sprdave - AHA!!! Now we are getting somewhere! I may not be buying pizza after all. Here is what I have:
> 
> My wall box current has black, red, white, and copper wires coming in. The whites are pigtailed together and run out to the load. Copper is grounded. Neither touch the thermostat. The black box wire runs to black. The red box wire runs to red. It is normally open
> 
> ...


Whats the problem? You have L1 and L2 coming into the box and T1 , T2 leaving.
Just hook up the new stat as a 2 pole stat. In THIS case, you would split the spliced whites and connect thru the stat.

I agree, you are either a green apprentice or not an electrician


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## sprdave (Jan 12, 2012)

Blind Frog said:


> sprdave - AHA!!! Now we are getting somewhere! I may not be buying pizza after all. Here is what I have:
> 
> My wall box current has black, red, white, and copper wires coming in. The whites are pigtailed together and run out to the load. Copper is grounded. Neither touch the thermostat. The black box wire runs to black. The red box wire runs to red. It is normally open
> 
> ...


I never said it couldn't POSSIBLY be done (sorry if I implied that), there may be the wiring there to wire it as a normal double pole thermostat. I don't think we have enough details to know that, but sounds like there is more wires in the box than the two connected, so it's quite possible.

I was talking about the way described in the OP won't work, which was the question.


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## Blind Frog (Aug 23, 2012)

OK....final clue:

Here is the existing wiring:









And here is the new thermostat diagram:









Can I safely wire the new thermostat to the existing wiring without the power being on all the time?


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## user4818 (Jan 15, 2009)

Blind Frog said:


> Can I safely wire the new thermostat to the existing wiring without the power being on all the time?


Go away.


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## Blind Frog (Aug 23, 2012)

Peter D said:


> Go away.


:no:


Not likely until I can find someone capable of solving this "simple" problem. It seems to generate multiple opinions with each asking.



Besides....a deluxe pizza is involved!



obscurum per obscurious


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## dronai (Apr 11, 2011)

Why is this allowed ? Go to HVACtalk, there really nice over there.


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## stuiec (Sep 25, 2010)

Blind Frog said:


> :no:
> 
> 
> Not likely until I can find someone capable of solving this "simple" problem. It seems to generate multiple opinions with each asking.
> ...


how 'bout: nuces nucis? :laughing:


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## dronai (Apr 11, 2011)

Blind Frog said:


> OK....final clue:
> 
> Here is the existing wiring:
> 
> ...




:laughing:


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## Speedy Petey (Jan 10, 2007)

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