Can I add underfloor zone before the pump on a S plan system

[markwilt]

Hi

I am going to change from a Y plan to a S plan to add underfloor heating to a conservatory.
I plan to change the mid position valve to 2 single zone valves in the airing cupboard then add a third zone valve control the underfloor heating.
All plans I have seen say you must put the underfloor zone valve after the pump but as the underfloor heating has its own pump I do not understand why I cannot T off before the pump as the boiler it in the kitchen is next to where I the underfloor heating pump is going to be.

I have got a horstmann h37xl 3 channel programmer & 3 zone valves so ready to go but would like to save myself some work if possible.


Can somebody please explain which way I have to complete it.


Thanks

Mark

 

[stevetheplumber]

i cant see why not as you say it has its own pump only concern would be the ufh pump robbing the flow to the main pump but balancing could rule that out i assume this is the easrier option so why not try it worst way you have to put it back the other way only other problem could be wiring if you want to run ufh without main pump comming on possibly you might need extra relays

 

[bill577]

it wont work, the pump on ufh systems is in a closed loop some of the time but you will be sending a run signal to the boiler meaning that the boiler will fire with no circulation in the primary circuit, install it as its meant to be installed , save your self a lot of grief.

http://heating.danfoss.com/PCMPDF/VVUDA202.swf

 

[diamondgas]

As above .... ufh pump circulates the ufh circuit only and relys on a supply of heat from the heating circuit!

 

[tamz]

Do whatever you think best. It will still work.............a bit.