DIY Doctor UK DIY Forums

hi,

new to this forum,

Please could anyone suggest how i can easily wire 2 pumps to run on a underfloor system and rad system using a 3 port valve,
at the moment i can only get the second pump to run all the time...have thought of using a relay..to select the second pump,

i am pumping the underfloor system and the rad system from each side of the 3 port valve with a comman rtn,

any thoughts would be helpful,

Many thanks

chris

I would have thought single pump and two zone valves might have been better, easier and more conventional. Sorry that doesn't actually answer your question though.

Cheers

yes..i did consider doing the system that way, but because the underfloor heating mainifold had a pump combined into the system, i went with a 3 port valve and 2 pumps...

wouldnt be a problem to change but most prob will set up a relay to work the pumps..
systems working fine as it is...so just needs tweaking...

thanks for your reply anyway..

I don't think the underfloor heating will work unless the second pump is installed because the resistance in the pipe will restrict the flow.

I can't quite visualise how a third zone can be added to what is essentially a two zone only system. Sorry, but I don't understand your description of how you have plumbed the underfloor heating now. I can't be sure, but from how you describe it, there is a risk of damage to the pump????

Connecting electrically should be simple, but it depends on how you want to control the second pump. Obviously, it needs a timer, a thermostat or both. What have you in place to use?

hi plumbob...thanks for your reply,

Underfloor heating is working fine...no probs as is the rad circuit,

flow from a 10kw heat exchanger is running through a 3 port valve...hot water down to the underfloor, with pump and blending valve...

second port from the 3 port is running the rad circuit...with a gunfoss alpha variable speed pump on this circuit..

comman rtns...back to the heat exchanger...fully sealed system...pump on the flow of the rad system...zone 1 if you like, pump on the flow into the underfloor manifold...zone 2...

so both systms can run independandly of each other... or together...alpha pump will shut down on the flow if its needed..

its only a electrical problem that im looking at as both the power for the pumps from the wiring centres etc are live on both cycles...

easist way is to put a relay on the elecrical pump feed and use this to switch from the programmer...

maybe a single pump would be more straight forward...with 2 zone valves...

systems working fine delivering good heat with no probs at all,...no a straight forward system as using a large thermal store with solid fuel and other inputs...

thanks for your time..

cheers

chris