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[hondaracer2oo4]

Ok so I have gotten my new system installed and I am trying to figure out how to control everything with a single thermostat. So I have a water to air hx in a plenum with my blower. That is a zone which has its own pump to feed the hx, the pump comes on when the fan comes on.

Then I have my oil boiler which is on its own loop and pumps into the primary loop. The oil boiler power is powered through a Ranco 111000 which I have the probe on the incoming line from the owb and when it drops to 140 it makes the connection and lights up the oil boiler. 

So currently I control the Fan and the pump in the plenum with a Honeywell RA89A1074. This is a Single pole Single throw. It has 24 volt transformer and switches the load via signal from the thermostat.

I would like to control the aquastat on the oil boiler with my one thermostat, the thermostat will call for heat and kicks on the fan and pump in the plenum as well as telling the oil boiler to fire which it can as long as the temp on the incoming owb water has dropped to 140. I tried hooking up the thermostat wire to both the aquastat on the oil boiler and the honeywell controller and the oil boiler backfeeds the honeywell control and causes it to run the fan in the plenum constantly.

My solution is to use a Honeywell R845A which is a single pole double throw control. One Pole you have to use line voltage and then the other pole you can use either line voltage or 24 volt. If I hook up thermostat wire to the 24 volt pole side and run it to my aquastat on the oil boiler will this work correctly? I just need to signal the oil boiler to fire or pump the loop when the thermostat tells the fan plenum to run.

[slimjim]

Ok I haven't finished my first coffee yet so I'm a bit foggy but it sounds like you are using the TT wire in parallel on the fan and boiler, it would need to be run in series. If that doesn't work then does your control at the fan have an isolated end switch?  I'm planning to leave the fair on monday morning are you ready for your boiler yet?

[hondaracer2oo4]

I am sort of ready, I need to move some logs out of the way and cut and remove the hardy out of the way. I plan to get back from camp Sunday night so I could get that stuff done Monday morning if needed. When did you think of bringing it by?

[hondaracer2oo4]

As far as the in series wiring goes, do I only run the white wire over to the boiler since I already get the 24 volt power from the honeywell on the forced air blower?

[hondaracer2oo4]

I got it figured out. I did have to isolate the fan control Honeywell RA89A1074 from the oil boiler aquastat. The way I did it was I used a RIBU1C relay. The signal side of the relay utilizes 24 volts to make or break the connection. I then ran the aquastat T T connections through the normally closed side on the relay(more on that in a second). So now the Thermostat in the house calls for heat which kicks on the Honeywell RA89A1074. The Thermostat continues the signal down the line to the RIB relay which then makes the connection for the aquastat the same as if you had it hooked straight to the thermostat but now the two controllers are separated. I initially hooked it up so that the aqua stat was run through the normally open side of the relay which I thought would mean when the thermostat called for heat it would close the connection and allow the aquastat to kick on. For what ever reason it was just the opposite. I switched it over to the normally closed side and everything works as it should. Thanks for your help Richard.

[slimjim]

I didn't do anything but you are welcome, we need to move a few stoves around before I can get to yours but I'd like to do it perhaps tuesday or Wednesday, would evening be better for you?

[hondaracer2oo4]

I can do either day, day or evening works. What boiler did you bring up to fryeburg?

[slimjim]

I'm running yours and I have another new one sitting in front of it that we pulled the access panels off from so people can see how easy it is to maintain, if you feel like making the trip up then give me a call, I've got some extra passes!

[hondaracer2oo4]

Cool. Thanks for the offer but I'm not going to make it. I'm driving to camp now, I'll be going by your place in about 30 mins.

[slimjim]

Ok have a safe trip and enjoy the nice weekend!