"Electrician" Question for 220V baseboard heater wireing question

[trekster]

Sorry this is not light show related but I need help on a question.

I have a heater that is 220vac.  They have 2 types of thermostats.

one with an off position and one that you can only turn down to 40 degrees but not "off". SPDT and SPST

I have the one with 2 switches.

The one with the off switch shows both legs of the 220 being switched.  One for the "OFF" switch and the other leg is the temperature switch.

IF either switch goes to "off" the heater will turn off.

See picture one.

This method takes to sets of wire.  One romex going to the thermostat and one romex going from the thermostat to the heater.

I already have 220V at the heater.  I want to connect one leg of the 220v to the heater.  Then run the other leg to the thermostat (wired as picture 2) and back to the other 220v side using only one romex run.

Both switches are rated at 220-240vac 22 amps.  The heater is an 8 foot 220V baseboard rated at 12 amps.

I do not see why I could not connect it as the second picture (switches in series).  They are just two dumb switches?  If the temperature gets met the thermal part opens and the heater goes off.  OR IF I WANT TO turn the unit off all the way I simply turn the dial all the way down to the off position and the heater goes off.

Here is the full link to the thermostat.  You are not allowed to view links. Register or Login  (Note: The picture shown does not show the off position just below the 40 degree mark)

Help me out guys.

My 16X18 foot mancave is almost done.  But it is cold..........  LOL

Thank You

Ron

[t0cableguy]

One piece of romex going to that thermostat should be fine. 10/2 romex would be better but you can get away with 12/2 because the heater is less than 20a. I would connect the two that are easiest to bridge between the 1 and 2 sides. on an electric water heater it is wired that way essentially doing the same operation.

my diagram below is a little different but essentially the same. every person would do it differently..

the only real problem with this is that the circuit is always live through the heater. You wont get any heat but you will still have 110v at all parts of the heater even though the thermostat is set to off. be sure to turn off the breaker if you have to do any work to it. there is no neutral in a 220v circuit. it is essentially two 110v poles put together.

[trekster]

Thank you.  Its six of one and a half a dozen on the other between the two methods. (your pic and my pic)

Ron

[t0cableguy]

Right and if it works don't fix/change it. You might open a can o worms you didn't know was even there.

My co-workers would kick my rear end if I didn't change what I said about 220. 110 comes from splitting 220v in the middle of the transformer winding. The laymens way of thinking it's what I said above.

[wftxlites]

If the 110V circuits are out of phase. I think they are if you have 220V between L1 and L2 then if you put them in series you will get a BANG. 

If L1 and L2 are in phase then placing them in series is OK.

Just a word of CAUTION

[t0cableguy]

I don't want to get get technical but unless you have a 3 phase service, and you would have to have a gigantic house for that, nearly every home in Usa has single phase 220/240v. the neutral splits the transformer winding so you get 110/120v. A 220v breaker ensures that the single phase 220/240v is being tapped. Whether you short the 220 or the half leg 110v to the neutral you will get a bang.

Three phase is essentially the same but your voltage possibilities add 440/480v. The higher the voltage the smaller the conductors that are required to safely run the circuit and the more efficient the equipment. Bangs happen anytime those out of phase conductors come into contact.

In layman's terms, use a breaker rated for the smallest step above its amperage, use the right sized wire  for the breaker rating and if your electrician did his job correctly, your add-on will be easy. Make sure you turn things off to work on them at the breaker and you will save your life every time. Any time you have any doubt, call a real electrician.

Just my friendly disclaimer.

[t0cableguy]

The labels on the diagrams and the labels on the thermostat and have little to do with what phase is actually going through them. The heating element is the load/resistance between the two phases which prevents the bang. No bang will happen if the wires are all pigtailed together on the one side of the heater going to the remote thermostat, but you will not have any function from the thermostat, this defeating its purpose. 220v works just like 110v but you don't have a neutral. They are both live.