united technologies 1158-120 fan timer board

[timd]

Hi there,

I've got an Olsen oil furnace that has a united technologies 1158-120 fan timer board. Only the R and W wires are connected to the thermostat so all I have is a heating setpoint.

We just had a Regency F3500 wood stove installed, and I've been researching the best way to wire up a switch to turn on Fan mode which according to the manual looks like a $5 switch between R and G.

I guess I'm looking for validation on that, please.

And then I guess the second thing I'm looking for is advice on the slightly less homebrew version. Is there any reason I couldn't directly wire in a Nest downstairs right by the furnace, and then put a Nest remote temperature sensor upstairs? My thoughts are that the cable routing path to the only 2 wire thermostat upstairs goes in such a fashion that I'm not going to be able to run a new 5 wire cable without opening the wall.

Thoughts/comments are greatly appreciated.

Link to the furnace manual: https://inspectapedia.com/heat/Olsen-Airco-HML-C-HMLV-C-Oil-Furnace-Manual.pdf

Cheers,

Tim

[Admin]

The fireplace fan should work when you connect a switch to R and G.  They do make 24 V switches that will open and close on temperature and that may be a more efficient way to control the fan.  Usually the fireplace comes equipped with the on off switch and when you install the optional fan kit, it will come with the thermodisc, but here is the part,

https://www.fire-parts.com/products/large-110f-43c-fan-heat-sensor

With the oil furnace, the Nest thermostat can work with only two wires and will charge its battery anytime the system is heating.  Otherwise, you could install the Nest thermostat close to the furnace and add a common wire between the furnace control board C terminal and Nest C terminal.