Gas and wood boiler set up questions

[Engelkefarm]

Hey im sure this question has been asked alot but im looking to set up a gas and wood boiler in my greenhouse. I want both units to work together if wood gets low gas will kick on. Im alittle unsure on how to set up circulators to work together. If one circulator is running will water flow thru the other that is off? I have radiant floor with a unit heater to dump any extra heat. The plan is to come out of cold manifold into wood boiler then into gas boiler up to the unit heater (aiming for a temp of about 120-140 into unit heater) after unit heater put a 3 way mix valve to reduce temp to around 80f. Does this sound right is there a better way of doing it? Something like the diagram but with addition of the unit heater

 

[Engelkefarm]

Hey im sure this question has been asked alot but im looking to set up a gas and wood boiler in my greenhouse. I want both units to work together if wood gets low gas will kick on. Im alittle unsure on how to set up circulators to work together. If one circulator is running will water flow thru the other that is off? I have radiant floor with a unit heater to dump any extra heat. The plan is to come out of cold manifold into wood boiler then into gas boiler up to the unit heater (aiming for a temp of about 120-140 into unit heater) after unit heater put a 3 way mix valve to reduce temp to around 80f. Does this sound right is there a better way of doing it? Something like the diagram but with addition of the unit heater

Hey im sure this question has been asked alot but im looking to set up a gas and wood boiler in my greenhouse. I want both units to work together if wood gets low gas will kick on. Im alittle unsure on how to set up circulators to work together. If one circulator is running will water flow thru the other that is off? I have radiant floor with a unit heater to dump any extra heat. The plan is to come out of cold manifold into wood boiler then into gas boiler up to the unit heater (aiming for a temp of about 120-140 into unit heater) after unit heater put a 3 way mix valve to reduce temp to around 80f. Does this sound right is there a better way of doing it? Something like the diagram but with addition of the unit heater

 

[Engelkefarm]

Also there are 2 inputs in back of boiler i only need one should i just cap the other one? They both feed same tank

 

[kjahnz]

Your drawing looks like you want to plumb the boilers in 'series'. I had that for a year or two, now I have primary secondary layout with closely spaced "t"'s which works nicely.
I think you should have proper cold water protection plumbing drawn into your sketch. Others with way more knowledge than me, should chime in shortly.
I think you could get away with one pump for both boilers, but your mixing valve and emitters should have it's own pump.

 

[Engelkefarm]

What was the reason for replumbing your system?

 

[kjahnz]

When I used the wood boiler, the propane boiler was radiating heat the same temperature I was generating from the wood boiler. That over heated the utility room in my basement, where the propane boiler is located.
Then when I was using the propane boiler, I was heating the wood boiler, that is located in my detached garage.
It may be ok for you, since both boilers are in the same building. I knew that having more control of the two boilers would be more efficient in my case. Hope this helps.
Look a little further into the number of pumps you plumbing schematic will require. I think your mixing valve needs water drawn through it to properly mix hot and cold water.

 

[davem3261]

Check out the sticky for primary secondary piping for boilers. I used one of nofossils diagrams and it works percectly.

 

[Engelkefarm]

Will do thanks

 

[Engelkefarm]

Any suggestions ?

 

[F4jock]

Any suggestions ?

If your only concern is backflow through the circ pumps, put a check valve in the pipes at the intake of each pump so you can't backflow. I assume that they'll shut down if their system isn't working. If you are coming off a common suction and want to get "techhie" get something like an Asco solenoid valve for each, plumb it into either the suction or discharge pipe of each pump and wire it in parallel with the pump motor. That way you'll isolate each pump when not in service and prevent flow through them as well.

 

[Engelkefarm]

The circulators have built in check valve i can always add a inline. I just get confused with diagrams. Some show thermal protection others do not. Im no expert my first plan was to keep looping water. Wood boiler-gas boiler-unit heater- radiant floor. Now im leaning towards circulating between both boilers when water is "ready" up to temp a second circulator will kick on and send water into unit heater and then to radiant floor