Adding a Second thermostat for OWB... yes I know

[k_kindig11]

Ok guys, I know there's a lot of posts here on this but I can't seem to find the answers I need. I just finished installing a Central Boiler 6048 and now have the thermostat situation left. I want to add a second thermostat to control just the OWB. I'd like to control just the "fan" from the furnace with the 2nd thermostat. I've read that I can tap into the Fan On/Auto switch. Basically cut the wire, run each end to the additonal thermostat to control the fan but do I just put one of those wires on the W and the other on R? If so, what about a power to the additional thermostat? My existing thermostat has these wires.

G Fan
Y Cooling
W Heat
RC A/C power
R Furnace power

My additional thermostat is only a 2 wire.

W Heat
R Furnace power

What is the best way to connect the additional thermostat to run the fan at a certain temp, then have the existing thermostat as a propane backup heat set at a lower temp?

I tried wiring the 2nd thermostat as stated in the central boiler manual (jumper wire from G of existing stat to W of additional stat, and jumper from R of existing stat to R of original stat) This turns on my blower properly but it also turns on my A/C compressor so that obviously won't work.

Any help would be appreciated.

 

[Dogsout]

I have hot water radiator heat in my house so I had it set up so that I could run just the house pump off of a thermostat when heat was needed. The OWB runs 24/7 so that there is always hot water in the exchanger if the house needs heat. I was not near smart enough to figure out how to hook this up myself so I had it done by a local heat/cool company. If you can get it figured out it is a great system as my house is set at 70* all the time and my back up LP furnace is set to come on at 60* should the OWB malfunction.

 

[stevetheboatguy]

My simple solution was to just turn the air conditioning breaker off. And disconnect the yellow wire from the #1 tstat. I just reconnect it in the spring.
Hope this helps.

Steven

 

[k_kindig11]

It seems I may be got it. I took the G (fan) wire off the existing stat and hooked it to the W of the additional stat (instead of using a jumper wire). I then ran a jumper wire from R to R on the two stats. Everything heat wise works as it should. AC does not come on when in heat mode. Then when I switch to AC mode, the AC comes on like it should. The only thing I need to experiment with is what the secondary stat needs to be set at during the summer when running AC so I don't have the fan running when the AC is not. I'm going to look into different scenarios tomorrow but for now, it's midnight and my bed is calling.

 

[Firestarter]

this seems to have worked for me. I shut the 2nd thermostat off when i turned the air on seemed to cycle fine.

 

[Guswhit]

I had that similar problem with mine a few years ago. Company I bought it from directed me to put in what he called "a peanut switch". Never heard of it, couldn't figure it out, finally ran a wire out to a light switch by the furnace to isolate the airconditioner-simple on in summer, off for the winter when the other thermostat was calling for heat. Would have to look at manual now to recall which wires I tapped.

 

[Backus]

Just cut the green wire and use each end on your new stat