Wood Boiler Thermostat & Pump Wiring For Forced Air

LegendsCreek

I am hooking up my workshop to my wood boiler. My workshop runs off of an oil boiler that is forced air.

I bought a water to air heat exchanger, and have installed it in my plenum, and am going to be hooking up the water lines next week. My question is about how I should wire it.

I am going to install a secondary thermostat for my shop as the wood boiler will be come the primary heating source and backup will be the oil boiler which will be controlled by the current thermostat which will be set lower and only turn on if the wood boiler stops heating.

I want to set it up so that the taco pump I am using to circulate the water will be triggered by the thermostat when it calls for heat, and the thermostat will not only turn on the Taco circ, but also turn on the fan in the oil boiler, but not burn oil. I do not want constant circulation on this zone of my boiler as my house will be constantly circulating the boiler water and I don't need 2 zones constantly circulating.

I am pretty handy with these things and am looking for some help figuring out the best way to do this. Any help is appreciated! Thanks

SWEI

Does the hydro air coil include any controls? If not, I'd probably start with something like this and then work out the hold-off logic on the burner.

Ironman

I install out door wood boilers (among many other things) and I have a control setup the will do it seamlessly using your existing thermostat. Forget that 2 thermostat method that wood boiler manufacturers try to push; it's seriously flawed.

P/M me if your interested.

hot_rod

Got a piping sketch? You don't want to flow through the wood boiler when the oil fired one is fired. We may have touched on that already?

LegendsCreek

The heat exchanger coil I bought has no controls on it at all. I am not opposed to wiring it all to the single thermostat if that is easier.

Hot rod, I am using thermostatic valves to prevent the oil fired water to go to the boiler. Last thing I want is my house boiler keeping my wood boiler warm! Huge waste of oil.

Ironman

LegendsCreek said:

The heat exchanger coil I bought has no controls on it at all. I am not opposed to wiring it all to the single thermostat if that is easier.

Hot rod, I am using thermostatic valves to prevent the oil fired water to go to the boiler. Last thing I want is my house boiler keeping my wood boiler warm! Huge waste of oil.

I don't quite see how thermostatic valves would prevent back heating the ODWB, but they would not be necessary with my setup.

LegendsCreek

Apparently, if the water temp gets below a certain temperature in the wood boiler, it shuts down transfer between the OWB and the heat exchanger. I have tested it and it does work. My oil boiler controls have a lower temperature point than what my OWB is set at, so it only fires oil if the water temp gets lower than the temp needed to close the thermostatic valve, so heat transfer shouldn't be possible once the wood boiler gets too low in temp.

Ironman

What stops the circulator under those circumstances?

LegendsCreek

Nothing. The circ will keep moving the water between the wood boiler and the house, but it won't go past the valve towards the heat exchanger. The same thing happens on the other side with the wrap around pump. It will keep moving water between the oil boiler and heat exchanger, but none of the water will be transferred past the thermostatic valve.

Ironman

LegendsCreek said:

Nothing. The circ will keep moving the water between the wood boiler and the house, but it won't go past the valve towards the heat exchanger. The same thing happens on the other side with the wrap around pump. It will keep moving water between the oil boiler and heat exchanger, but none of the water will be transferred past the thermostatic valve.

Got a diagram?

LegendsCreek

I can't find a diagram online. How strange. My neighbor lent me his diagram so I knew how to install it (they didn't give me one). I will see if I can take a scan of it.