240v electric baseboard heater & thermostat

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Old 12-04-15, 05:37 AM
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240v electric baseboard heater & thermostat

Decided to change both due to low heat output from rusty unit and the thermostat not working properly. Thermostat not sensitive so it stays on until room gets very warm acting like an on/off switch rather than a thermostat. Only one heater on this line.
Old thermostat is one pole with one hot passing straight to heater therefore always hot. Shouldn't it be two pole which I replaced it with. Or was that an approved method? The reason I ask is because I suspect thermostats in the house may be wired that way,
Thanks.the other 4
 

Last edited by paulmess; 12-04-15 at 07:33 AM.
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Old 12-04-15, 06:12 AM
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Decided to change what? Did you change the heater, the thermostat or both? Where is your thermostat located? Is it on the wall or at the end of the baseboard heater?

There are several different types of thermostats. Some are single pole and some are double pole. You alluded that the thermostat is turning the heater on and off but you just don't like how it controls the room temperature. Since it's turning the heater on and off it sounds like the thermostat is wired correctly. When wired incorrectly the thermostat often goes "poof" and trips the breaker the instant you turn power on to the circuit (ask me how I know ).
 
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Old 12-04-15, 06:18 AM
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Not getting your logic.
A thermostat is a form of a switch, it's just automatic.
There should always be power coming to it, it's not going to be using any power until the contacts close and the heater warms up.
If you removed a single pole heater thermostat that's what you should have replaced it with.
 
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Old 12-04-15, 07:26 AM
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Two separate issues

1. When I set the thermostat to 68 degrees (or any other temp higher than the existing temp) it would call for heat and continue to call for heat until I turned it all the way off even if the temp reached 75+. The new one cycles on and off as designed hence problem resolved.

2. Please excuse my terminology if not correct. In the junction box that the thermostat was installed on their are two supplies in and one out. One hot is switched by the thermostat. The other bypassed the thermostat. The two hots are then connected to one cable which is routed to the baseboard heater. The two whites (neutrals) are capped off and not in use.

The old thermostat is actually two pole but only one was in use.
 
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Old 12-04-15, 07:30 AM
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Wall mounted thermostat. I replaced both thermo and heater with new units. It is working.
 
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Old 12-04-15, 09:52 AM
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The baseboard heaters are 240v. A single pole thermostat only breaks one leg of the power. Technically the heater won't create heat since it doesn't have the needed 240v but it's also technically not dead.... as from a servicing point of view.

Sounds like you've got everything under control there.
 
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Old 12-04-15, 09:55 AM
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The two hots are then connected to one cable which is routed to the baseboard heater. The two whites (neutrals) are capped off and not in use.
You said this was a 240 volt heater, there is no neutral in a 240 volt circuit. Most likely the whites are the other leg going to the heater and that leg isn't being switched.
 
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Old 12-05-15, 07:36 AM
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Ideally both lines or wires or conductors going to the 240 volt heater should be "switched" using a double pole thermostat. (I supposed you could call the lines legs since they connect to opposite legs of the 120/240 volt service.)

Practically you will often find just one line so switched.

1. The thermostat is single pole.

2. The thermostat is double pole but is used to control two heaters on two different circuits.

3. Only one of the llines comes and goes via a "switch loop" single cable to the thermostat that is beyond the heater; the other line goes directly to the heater only.

Even when a double pole thermostat switches both lines going to a single heater, in most cases the two lines are not switched on or switched off together at exactly the same moment as the temperature changes. The importance of switching both lines is so the heater is dead when you turn the thermostat to the off position.

To avoid frying a double pole thermostat due to a mistake making connections, you may try wiring up just one pole and test it for proper operation with the heater, before hooking up the other pole.
 
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Old 12-05-15, 08:36 AM
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2. The thermostat is double pole but is used to control two heaters on two different circuits.
You cannot use a two pole electric heater thermostat to control heaters separately.

On a two pole thermostat.....
One set of contacts is made as soon as the stat is turned on.
The second set of contacts are the cycling contacts.
 
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Old 12-06-15, 07:45 PM
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... The old thermostat is actually two pole but only one was in use. ...
Did it ever work correctly, cycling on and off? Maybe, since day one, the pole being used had the contacts that were made as soon as the thermostat was turned up at all and then stayed on.

Now, on another note, I'll swear that I had a 2 pole line voltage thermostat both of whose poles cycled. Now I'll have to go find it. It's still in the box, never used.
 
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