Adding UFH zone to a Y-plan system

[lchris21]

Fist of all hi all, first post. Stumbled accross you lot whilst googling away.

With the help of a few other online forums I'm trying to get clued up on the best way of adding a recently installed UFH system in a kitchen extension, to an exisiting Y-plan open vent system I have.

To cut a long story short, I'm putting in a new Vaillant Ecotec 418, and am going to use thier control system & programmer to provide the following:
HW and CH for the existing system controlled by a room stat and cyl stat.
New room stat to control the added UFH heating zone which will include an exisiting rad in an adjacent connected room. Basically a 3 channel setup, CH + UFH + HW............

Using advice already recieved I've arrived at the following, new zone via a two port valve, controlled by the new room stat. My thinking behind connecting the exisiting rad in the new zone before the UFH blending pump is that the UFH needs water of a lower temp, so the return water out of this rad should be ok??

Any advice greatfully recivied
Cheers

 

[unguided1]

Providing that your underfloor heating manifold has its own pump and blending valve you need to plumb it in to the primary circuit from the boiler.

If you plumb it in after the zone / three way valve, you may find that the under floor heating will rob heat from the rest of the system

 

[lchris21]

as in the pic I've attatched?

After the pump but before the 3 port valve ?

cheers

 

[unguided1]

I would go before the pump because there are gonna be times when your radiators and cylinder are satisfied therefore your existing pump will be turned off, but your underfloor may still be calling for heat

 

[Toddyplumb]

If you are going to all that trouble just remove 3port and fit 3 zone valves dead simple

 

[lchris21]

If you are going to all that trouble just remove 3port and fit 3 zone valves dead simple

another option I have not considered?

What advantage is there in fitting 3 x 2port valves?

 

[Magicplumb]

Do it as per your drawing, its the only way to do it. It will also need a zone valve to operate on its own. Using the orange and grey on the valve to switch the voltage free link on the boiler.

 

[lchris21]

I think I'm going to bite the bullet and covert from Y-plan to S-plan. Seems a little more flexible in the zoning option which means I can get the UFH on earlier than the rest of the house without firing up the main CH.

Think I'm going to go with Toddy.............

Am I being too simplistic here, but I'm assuming I just need to junk the 3port valve and sub in 3 x zone valves plus install some sort of bypass?

I really want to control the UFH zone separately from the main CH but cannot see how I can achieve this as the 3port will have to be open to allow the pump to circulate the water??

Right, off to research changing Y-plan to S-plan.......................the wonders of the tinternet

 

[Spudhater]

S Plan is the way to go, install auto bypass as well.
You want the UFH to come on a couple of hours earlier than main heating and go off 2 hours earlier.

 

[lchris21]

Righto, on to the controls
I'm thinking Honywell S-plan pack for ease of use, compatibility and good reputation. Not the smartfit which seems easy plug and play stuff, as they only seem to have two outputs for CH & HW valves? I need three!!
So, I need to get an extra 2 port valve for the UFH loop, plus a programmable room stat to control this?
Will I be able to integrate the extra prog room stat into the wiring center without too much
Cheers

 

[Toddyplumb]

Yes its easy to do . Or you can get 3 channel programmers , Horstman do one , check with Honeywell

 

[martin b]

Is it possible at all to tee into the primary flow before the pump to fit ufh? im working with a boiler downstairs and a pump and cylinder in the loft.