Twin Boiler Wiring

[pete.l]

Went to wire a boiler the other day, got there and found 2 identical boilers paralelled up, a pump and valve for the hot water and a pump and valve for the heating! Boilers require pump run on.
Thought of a modified 's' plan and relays to control the pumps but cant get pumps to run seperately. Any ideas??

 

[Guest123]

Hey Pete.

Could you not treat it as almost 2 seperate s plans??

As you have 1 zone valve for each then these surely would control each pump seperately with 1 switch wire from each to fire their respective boiler??

 

[pete.l]

Hi Lennytheloon,
No the plumbers want both the boilers to run together!!
Will revisit site armed with some extra relays and have a play.

 

[Guest123]

Hey.

I see what your predicament is now, I misread and thought that they were to be running seperately.

Yes a relay arrangement is the answer, two switched lives in to relay one for heating one for hot water and two switched lives out, one to each boiler.

The relay will stop any backfeeding between heating and hot water circuits.

Maybe another relay in the same fashion for the pumps too.

Cheers

 

[leenowell]

I have exactly the same situation but with several heating zones, UFH, secondary return loop etc. Each circuit has a 2 port motorised valve controlled by timers/ prog room stats and the relay side of these valves all return back to fire the boiler once opened. I have wired it all up to one of the boilers and it is all working fine. My question is.... Can I simply wire the second boiler in parallel with the first? I was thinking that the valves prevent any backfeeding anyway and the end result is that I need both boilers to fire if anything calls for heat?

thanks in advance

Lee.