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msngr321 · Mar 23, 2012, 10:00 AM

I wish to control the temp. in a small insulated area (4'X4') with a Hunter 24v thermostat. I have purchased a Omron G2R 24v relay to control line voltage (120VDC) to simply turn off and on power to a heat lamp. I can't seem to get the contacts to operate in the relay with the thermostat. What else do I need and what is the wireing diagram for this setup?

ballengerb1 · Mar 23, 2012, 11:57 AM

So the heat lamp is the only source of heat, right?

tkrussell · Mar 23, 2012, 01:27 PM

Have one wire from 24 volt power source, I assume you have a small 120 volt ac to 24 volt ac transformer, to stat, then to coil of relay, have the remaining contact on coil run back to remaining connection of the 24 volt source.

Be sure the coil voltage rating matches the 24 volt source.

msngr321 · Mar 24, 2012, 09:16 AM

Originally Posted by tkrussell

Have one wire from 24 volt power source, I assume you have a small 120 volt ac to 24 volt ac transformer, to stat, then to coil of relay, have the remaining contact on coil run back to remaining connection of the 24 volt source.

Be sure the coil voltage rating matches the 24 volt source.

The heatlamp is the only heat used to heat the (4'X4') space. My thermostst is powered by two 2AA batteries, same as used to control home AC. I have followed the (two wire heat only instructions) that came with the thermostat but I can't get it to open and close the points in the relay (which in turn would turn off and on the 120v power to the heat lamp. What am I doing wrong?

msngr321 · Mar 24, 2012, 09:32 AM

The heatlamp is the only heat used to heat the (4'X4') space. My thermostst is powered by two 2AA batteries, same as used to control home AC. I have followed the (two wire heat only instructions) that came with the thermostat but I can't get it to open and close the points in the relay (which in turn would turn off and on the 120v power to the heat lamp. What am I doing wrong?
My thinking is ,if the 24v thermostat will control the AC for a home, why not for the smaller space (4'X4'). So I bought a 24v DC -120v/220v AC relay for the 24v thermostat to control as an off and on switch that would be turning on and off the heat lamp at a set temp.
Thanks so much for your first response, tkrussell.

stanfortyman · Mar 24, 2012, 12:12 PM

Do you really think the two AA batteries are providing the 24v needed to operate the coil in the relay?

The AA batteries are to run the thermostat only, NOT the load it is controlling. The thermostat is basically just an automatic switch.

You need a 24v power source, such as a transformer like TK mentioned. The thermostat will control this 24v source to power the coil of the relay, the contacts in the relay will control the heat lamp.

The wiring diagram is on the relay itself. You just have to wire the coil power through the thermostat like we have been saying.

ballengerb1 · Mar 24, 2012, 12:43 PM

Stan is correct, two AA gives you either 1.5 volts or 3 volts, enough to make the chip in the stat work, not the 24 volts.

msngr321 · Mar 24, 2012, 06:01 PM

Thanks Guys:
I am not knowleggable about voltage and such. That is the reason I came to you. You have been very helpful I will add a transformer and try it again. Thanks again.

msngr321 · Mar 25, 2012, 02:54 PM

I would still need to know what kind/type of transformer I need to look for to finish my project. Again my thermostst is operated by two AA 1.5 batteries and I have a five pin 24V relay. What should I ask my electrical supply house to get the correct transformer?
The relay has two pins for 24V and three pins for choice of open or normally closed contacts.

stanfortyman · Mar 25, 2012, 05:23 PM

If you hard wire the transformer to the relay the coil would be energized all the time. The thermostat will break one line between the trans and relay.
The diagram on the relay will tell you which terminals will be N-O and N-C. You want N-O, so when the t-stat makes it will energize the relay coil and close the "normally open" terminals.