existing Y plan system,adding a second zone for UFH HELP?

[flybrazil]

Hi lads, Im a Gas Safe registered engineer, awaiting aproval to join the Combustion Chamber......
Please can anyone help?
1-There is a Worcester Ri heat only boiler on an open vent system running on a Y plan.
2-Mid position valve its a switchmaster (blue one)
3-heating control its a potterton P2000 double chanel and heating stat on the wall.

I've added a 2 port honeywell valve to create a second zone, straight from the main flow from the boiler.
That goes to the UFH control stat/programer as well as pump/mixing manifold of the UFH.

Problem is that the boiler has the bloddy pump overun facility as a safety feature, and everytime the UFH comes on, also it puts a demand on the existing Y plan heating system, thus, overriding the original house's controls and by kicking the pump.

One think to remember is that, whenever the demand on heat its OFF on the existing heating system, the mid-position switchmanster valve its open for heating.

I cannot figure it out how to stop the heating being on in the main property, when im only putting a demand on the UFH at the newly build extension?

Can anyone one please send me some clues?

Much appreciated

 

[DP]

Replace the three port and also fit a bypass. Three port to be replaced with two two port valves

 

[dcawkwell]

I assume the underfloor will have a separate timer
therefore this will be wired via the underfloor zone valve to the orange wire of the 3 port valve.
So demand from either the house or the underfloor will make the orange wire live and switch the boiler on.
If there is any pump overrun and the house heating is off it will dump
to the cylinder.

Seems ok to me.

 

[picasso]

View media item 30852
you need a blocker valve installed before the 3 port, I will need to have a think about the wiring.

 

[Dan Robinson]

Two port valve between mid-position valve and by-pass with wiring intercepting the y-plan call for heat should be fine.

 

[Dan Robinson]

As per picasso's drawing. Sorry didn't see it... Posting from an iPod tonight.

 

[picasso]

The orange from the 3 port connects to the brown of the 2 port blocker valve, and the orange from the 2 port is the sl for the boiler, this way you can have the ufh / rads / hot water running independantly.

 

[flybrazil]

thank you all for the clarifications, much appreciated.

 

[flybrazil]

I assume the underfloor will have a separate timer
therefore this will be wired via the underfloor zone valve to the orange wire of the 3 port valve.
So demand from either the house or the underfloor will make the orange wire live and switch the boiler on.
If there is any pump overrun and the house heating is off it will dump
to the cylinder.

Seems ok to me.

it makes perfect sense now

 

[flybrazil]

The orange from the 3 port connects to the brown of the 2 port blocker valve, and the orange from the 2 port is the sl for the boiler, this way you can have the ufh / rads / hot water running independantly.

tropo bello....belissimo!!!!