I currently have a two-wire system (R/W) going to my thermostat. The furnace is an oil heat system with a blower to force air. There is currently a Honeywell R7284 Oil Primary Control where the thermostat wires are running to, both labelled at T T.

Current thermostat wire hookup

I tried looking at the manuals for the system but I'm a little out of my depth as I've not had to mess around with an oil system until I purchased this home, but would like to modernize a bit and add a Wifi Learning Thermostat for convenience.

The cable run up to the wall is pretty straightforward and simple, so I'm hoping one of those other terminals is able to act as a C-wire to provide constant power. Some of the other posts mentioned an F F terminal but mine has a 3/2/1 instead.

Thanks in advance.

1 Answer 1


I found the manual here: https://jacksonsystems.com/wp-content/uploads/2020/04/R7284-Installation-Manual.pdf

Judging from the sample wiring diagrams and the troubleshooting instructions for "Low voltage xx% low"

 terminal 2 is   C
 terminal 3/T is R
 terminal T is   W

It's possible that the installer knew this, but also possible that they just guessed right.

It is not specified how much current is available to drive your smart thermostat load.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.