Wiring external furnace to L53

[OakSavannah]

I have an electric house furnace as my aux heat source in my kiln. Doing a new install of a L53 and all of the wiring diagrams show the control unit sending 120V power to a relay.  The furnace just needs contacts closed - think of your house furnace and the wall controller. Is there a way I can hook up my furnace to the L53 to simply close the contacts to turn it on? If not then I suppose I can rewire the furnace with a 120V to 240V relay to accept the 120V signal. Thank you.  

[btulloh]

Either put a 120v relay on the furnace or a 24v transformer on the output of the L53. 24v transformers are cheap and available at any hardware store, electrical supply, or hvac supply. You'd be looking for a bell transformer (doorbell) or hvac transformer for controls. 

[OakSavannah]

Hadn't thought about the 120V - 24V transformer route. Simple, I like it.  Thanks.  

[K-Guy]

That house furnace will probably cut-out at 104°F as they usually have thermal overloads built in for safety.

[doc henderson]

I have not tried it but looking at an electric clothes dryer heat element kit for about 30 bucks and temp cut off closer to 150° and easily changed.  I was looking at it for a hot box to sterilize.

[OakSavannah]

Thanks all - as far as the thermal overload on the furnace it is 160 and I've had it right up to 160.  Used this kiln for the last few years but had an Arduino solution I created for controlling heat/compressor but got tired of being a programmer and dealing with home dehumidification units so installing a L53.  For the L53 controlling the furnace and just closing the contacts, I found a solution.  The heat relay in the L53 is a 4 pole 4 throw and only one line is being controlled on it.  I took the 2 24v thermostat wires and put them on either side of one of the vacant poles.  

[doc henderson]

I think the key is not to run the compressor at the high temps or it can overpressure, and throw another switch in the unit.  but you may be way ahead of me.  hope it works for you.  

[K-Guy]

For the L53 controlling the furnace and just closing the contacts, I found a solution.  The heat relay in the L53 is a 4 pole 4 throw and only one line is being controlled on it

The way the heat circuit works on the L53, the heater cuts out when the compressor starts, so that it can used on a 15 Amp breaker. Once you get your unit call me at 800-777-6953 and press 6 when the system answers or ask for Stan.