Hello I am new to this.

I purchased and installed a Hunter programmable thermostat [Auto Saver #44550] to go with My Lenox High Efficent gas furnance. Long story short after installing the thermostat it did damage to the tune of $700.00. [Damaged my ignation control and my gas value] My furnace company said I needed an isolation reley before I installed the thermostat and hope that it did not do any damage. A little to late for that idea.

Hunter fan company which produced the thermostat said it was not their fault. But the furnace company they always put a isolation reley with a programmable thermostat.
How would I know to install an isolation reley?
After the fact the people at Lowes and a True Value Hardware did not know this.

Is this correct? Help!
Thanks!
TodLee

 

I have never heard of this.

I think you had a wired crossed or wrong, and shorted out the controls. or didn't turn of the power when you wired the new stat.

This furnace a single stage or two stage?

If they put in a relay, how does the stat get it's power??

 

Hi Jay11J,

Before I started I had a frenid with me and we made sure the power was off.
I am 99.99999% sure we did not cross any wires because the week before he had installed a Hunter programmable thermostat himself and he has more experience than me.
The furnance was working but erraticlly.

The last time I tried I took the thermostat to Lowes and they said to [check if it is the furnance or the thermostat] by over riding the thermostat by toching two wires together with the thermostat off of the wall. Before attempting, I called Hunter and with them on the phone and the thermostat off the wall I touched two wires together with the power on to the furnance and got nothing. That's when Hunter said it was the furnace.

I even called Lenox who manufactured the furnace with the model# and serial# and they said the same thing "WE ALWAYS INSTALL A ISOLATION RELEY WITH A PROGRAMMABLE THERMOSTAT'' I asked can you show me or tell how I can verify this? He said only if I was a certified thec. working for a company. He however said I can use him as a witness.

How can I tell if mine is a single or two stage furnace w/out calling someone.
Thank you for the reply.
TodLee

 

TodLee,

I once had to install an isolation relay on a Lenox system to control the cooling mode. Once I started investigating the problem I realized the t/stat would drop just enough voltage to the "cool" wire to cause the contactor to drop out. I installed the relay (one of the ice cube types) and wired as so (AFTER all power is removed from the system....make sure the 24v side is dead also):

"Cool" wire from t/stat to coil side of relay (normally #85 or 86 terminal)
Ground the other side of the coil
Hot wire (24v) to terminal #30
24v "cool" wire to compressor to #87a (N/open)


I don't see any reason the same wiring wouldn't work with the heat mode. A word of caution though....I think most gas valves work on approx 3.5 volts so the relay would have to feed the gas valve the correct voltage....NOT 24v!

Hope this helps.

 

That is still new to me about this relay.

I just put in a Honeywell Vision Pro on my supervisor's furnace. and he has the Lennox G61v.

I must say, I do hear alot of horror stories on these off hand t-stat like Hunter. I have not seen it for myself tho..

 

I agree with you about the Hunter t/stat....never experienced any problems installing/using Honeywell. A quick voltage check at the t/stat will reveal if the heat mode is being signaled and the same check at the gas valve. I'd bet the t/stat supplied 24v to the gas valve/related controls causing the damage, thus the reason for the isolation relay.

 

Thanks for the information.
I can't belive I am the only that has had this problem.
I asked this same question to www.AskTheBuilder.com {Tim Carter Cincinnati, Ohio} "He tells people NOT to install thoses things themselves....
The electrical components in a modern furnace are VERY sophisticated."

I did not know Hunter thermostats have had some horror stories.

I feel Hunter has some obligation to notify the consumer about installing thermostats on modern furnaces. I guess the next move is to small claims court.