Adding UFH to Y-plan system

[mjl117]

Hi
I've had a single storey extension built with underfloor heating (about 35m2)
The plumber assured me that the UFH would have it's own "zone", but from my understanding of reading about Y-plan, S-plan etc this isn't the case based on the design of my system.

Previously I had a Y-plan (sealed) system which fed either the radiators or the hot water cylinder.

When the underfloor part was added a new 2-port valve was installed on the feed from the boiler as per the image below:

Do I need another 2-port value before the 3-port?

Or should it be converted to an S-plan? If so, does that 'just' mean adding 2x 2-port values for the radiators/cylinder in place of the 3-port valve?

I'm going to speak to the plumber, just rather have some basic knowledge before I do!

Thanks

 

[Madrab]

Not needed - the 2 port controls the UFH zone and that should be controlled by it's own thermostat(s)

The 3 port will be controlled by the HW cylinder stat and the radiator stat.

Y plan systems are now really considered to be obsolete and once the 3 port S-motors goes (theydon't last due to the way they work) then an S plan would certainly be a step in the right direction. Yes - 2x 2port valves, one on each leg to the CH/HW and a bit of re-wiring and the possibility of a bypass being needed.

I take it the blue arrow to X is pointing in the wrong direction? What is X anyhoo?

 

[mjl117]

Thanks, the X is a mixer (or last least what I assume to be a mixer)

I have two thermostats. A Nest to control the radiators and hot water. A Heatmiser to control the UFH.

The Nest is currently switched off (i.e. no demand) and I've just turned the Heatmiser up which is now demanding heat. This has resulted in the radiators coming on.

 

[Madrab]

The Nest is currently switched off (i.e. no demand) and I've just turned the Heatmiser up which is now demanding heat. This has resulted in the radiators coming on.

Ah ok, apologies, of course that's because the 3 port always has a port open.

To shut down the CH/HW side of things totally then yes just modify it to a an S plus so ideally you will have 3x2 ports by the end of it. No point in putting just one in and keeping the 3 port as it would just get overly complicated for no reason.

 

[picasso]