electric base board heater question

[forgeblast]

Hi we have electric baseboard heat with a wood stove supplement.
The heater in our one room is not turing off at the temperataure that the thermostat is set at. It just keeps on until it is very very hot. I replaced the thermostat and it it still doing the super hot on. Any suggestions or has anyone had to deal with this?

 

[Highbeam]

Does it ever shut off? I just wired one of these in over lthe last couple weeks and they are very simple. You either have the thermostat wired wrong (hard to do), your thermostat feels cold due to poor location (more likely), or you are doinking with the stat for a different heater (unlikely but would be funny).

There just isn't much to these things.

 

[BobRip]

Many years ago I found several of these stats that were not adjusted correctly inside. I had to adjust a set screw. But two in a row. Probably not. It sounds like it's wired wrong.

 

[mbohuntr]

Try rotating the thermostat until it turns off, you should hear an audible click. If your not turning off at any setting, the T-stat is either wired wrong, of faulty. If the t-stat turns off, but the heater doesn't. you may have a bad relay in the heater.

 

[randy41]

Has it ever worke properly? Like last winter?

 

[BobRip]

Try rotating the thermostat until it turns off, you should hear an audible click. If your not turning off at any setting, the T-stat is either wired wrong, of faulty. If the t-stat turns off, but the heater doesn't. you may have a bad relay in the heater.

The click check is a good idea. I have never seen a relay in one of these heaters. I guess it's possible.

 

[mbohuntr]

You have to have a relay/switch somewhere, the t-stat is 12-24vdc, and the heater is likely 220 ac using around 30 amps. If your not familiar w/ electrical equipment, don't mess w/ it. chances are the relay is solid state and doesn't look like a traditional relay. There is also a thermocouple in there. Have an electrician look at it once you determine that it's not the t-stat.If you haven't messed with the wiring, it's time to call in the pro. I'm not sure whether they use a SCR, or Triac, but they use more than enough current to kill you!



Silicon Controlled Rectifier (SCR)

 

[kenstrac]

Line voltage thermostats either have 2 wires or 4 wires the 2 wire thermostat does not say off 4 wire thermostats say off on them and are wired with romex wire
low voltage thermostats have very small wire going to them and have a relay that could be mechanical, solid state or mercury.
what one do you have?

 

[mbohuntr]

Are the line voltage t-stats the ones mounted on the unit? I've never encountered one... Never Mind, I looked it up... Neat! and dangerous for the careless do-it-yourselfer...

http://www.honeywell-thermostat.com/line-voltage.html

 

[RonMar]

I have never seen a low voltage thermostat(and it's required relay for this high current application) used with a baseboard heater. I have only ever seen 2 wire line voltage thermostats. They use a bi-metalic strip that changes shape with temperature changes. the knob changes the mechanical relationship of the metal strip with the actual switch mechanism to set the on and off temperature that the thermostat attempts to maintain.

The click is the switch either opening or closing. No click, means no contact change of state. Most usually have a set screw and lock nut to "calibrate" the mechanism so the switch function and indicated temperature/knob position agree with the actual room temperatures. If it is working properly, it should click when the knob indicator mark reaches the actual room temperature on the thermometer scale. I had one that wouldn't always turn off when the knob was rotated to the lowest position. You had to push on the knob to get the unit to click off.

The wiring is simple. One hot leg goes directly to one of the two wires on the heater. The other hot leg goes to one of the 2 wires on the thermostat. The second wire on the thermostat goes to the other input wire on the heater. There is also a thermal snap switch in the heater itself that opens the circuit if the heater overheats.

 

[kenstrac]

Single pole thermostats do not have off written on them since you are only shutting off 1 leg and the other leg is still hot,double pole thermostats shut off both legs and are marked off this is a UL requirement.
low voltage thermostats tied into relays are used when people do not want to here the clicking of the thermostat or the load is to large for the line voltage thermostats or when different day night temps are needed or other energy saving programing.

 

[forgeblast]

I Had a simple thermostat installed before it started going a lilttle crazy. It would turn off when i lowered the thermostat but it would not keep the temp that i set it at. So i bought a digital thermostat that would allow me to set it for night and day temps. Im still having the same issue with it.
We used a space heater all last year to keep the room warm.

I called an electrician, he will be coming out in the next week. he also said it may be a bad relay in the heater.
Ill keep you posted to let you know what it is.

 

[Highbeam]

My experience is like Ron Mars. These are line voltage stats with no relays. I have used three kinds of stats. There is the old fashioned bimetallic spring ones which are being phased out, then there are the modern stats that have a battery and some internal electronic temp sensing device but no digital display, and then there are the third ones which I like the most that also have a battery and no bimetal spring but they are programmable for multiple temps and times.

They all click when the 220 load is activated. All have been two wire stats that required load and line to be on a particular wire which I never understood why but complied.

Note that these common two wire stat setups will leave one hot leg energized at the heater so you can get a 110 shock if you fiddle around in there while vacuuming the element or whatever.

Let us know what the electrician shows you. I'm betting the stat is busted.