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Rick Mather
Rick Mather, HVAC Technician
Category: HVAC
Satisfied Customers: 3634
Experience:  35 years experience, HVAC
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I am trying to replace my Honeywell LR1620 thermostat and an

Customer Question

I am trying to replace my Honeywell LR1620 thermostat and an 8030? thermostat with programmable ones. We have 3 Lennox units. Each unit is 2 twinned Pulse 21 Gas furnaces. They always run together. One furnace starts and then the other does. If the 2nd furnace does not kick on, the first one will shut down. Each unit has its own thermostat. Do you have any suggestions on which thermostat, or what specs I need? Thank You so much.
Submitted: 7 years ago.
Category: HVAC
Expert:  Rick Mather replied 7 years ago.



I think this control might be what your looking for to control the two furnacesand if you call them maybe they could do all three for you

Customer: replied 7 years ago.

The thermostat you are suggesting is a two stage thermostat. We currently have two LR1620's and one that looks just like a standard round honeywell. I could only find the this number: T87F2808 2 8030. I did not take it apart other than removing the ring. They are heating and cooling thermostats. From other research I have done, I think they are single stage thermostats.


The furnaces are twinned to run as a single unit. They both run, or neither one runs. We have three sets of twinned furnaces. I have tried to get several local HVAC guys to come look, buy our area is in a huge growth spurt, and no one we trust has the time for a little job.


Are our current thermostats single stage, or are they two stage?

Expert:  Rick Mather replied 7 years ago.
I don't know if your are present thermostats are two stage or not but Iwould suggest that you run them has two stage that way when its mild out your not wasting fuel. Maybe you look up a control contractor and still them what and how you want these to run I know Johnson Conctols has what they call ABC contractors for just places like yours
Customer: replied 7 years ago.

I live in Gillette, WY. I do not believe we have any Johnson Controls here. I will check. I know I have seen them here, but they are from out of state. Our mild weather heaters are usually to put on another layer, or take one off. I was under the impression you have to have a two stage furnace to have a two stage thermostat. From what you have said, I am assuming this is a false assumption.


Thank you so much for your help. Hope you have a blessed day!

Expert:  Rick Mather replied 7 years ago.
Well you can run two furnaces from a two stage thermostat if wire correctly with isolation relays and that might work for you
Customer: replied 7 years ago.
I am sorry, I am not making myself clear. The two furnaces run as one unit. They are wired to the thermostat as one unit. They either run or are off. They act together as one furnace. They are not, and will not be wired with isolation relays. If one or the other furnace does not ignite the burner, neither one will run, they just shut off. They will not run independant of each other. I do not want to get a thermostat that has features we can not use. Can you recommend a single stage thermostat to use?
Expert:  Rick Mather replied 7 years ago.
Rick Mather and other HVAC Specialists are ready to help you
Customer: replied 7 years ago.
Thank you.
Expert:  Rick Mather replied 7 years ago.
Thank You and God Bless

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