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Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 19494
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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I've got reznor gas furnace m# US-75 I needing wiring

Customer Question

Hey I've got reznor gas furnace m# ***** I needing wiring diagram on how to hook up. Can you help
Submitted: 11 months ago.
Category: HVAC
Expert:  Rick replied 11 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

Are you sure about that model number? I'm coming up empty on specs for that number

Customer: replied 11 months ago.
I see mistake I made. UA-75
Expert:  Rick replied 11 months ago.

Ok, this model was discontinued 40 years ago. There are no manuals or wiring diagrams available. If you're sure it's in working order maybe we can figure this out if you can give me some pictures of the wiring connections. You can post pics here by clicking on ADD FILES next to the SEND button

Customer: replied 11 months ago.
I'll try describe it best I can. It has a yellow a black and a red wire that runs through conduit to limit switches. A white and a black wire through conduit to fan motor. A white and a black wire to transformer they all come into junction box. The white from transformer and white from motor tied together. The black from transformer tied to yellow from limit switch. The black from limit switch tied to black from motor. Red from limit switch is alone. On the outside of transformer has a white wire running to gas valve connected to brown wire going into heater. Another terminal on transformer has bare black wire. Last plug on gas valve has a bare black wire connected to another brown wire that runs inside heater along with brown wire I mentioned before.
Expert:  Rick replied 11 months ago.

The best I can make out from your description would be to connect your line in black to red and white to the whites. It sounds like there are 3 terminals on the limit a line in and 1 out to the fan the other out to the transformer. Also since this is a used unit and the only leads not connected in the junction box are red & white which would indicate they were originally tied to the line in. Your thermostat leads should connect in series with the transformer lead not directly connected to the gas valve.