underfloor heating - Y plan

[angeldunk]

Hello All, this is my first post here.
I am struggling to understand how to intergrate my UFH system with current central heating system

Have a Icos system he 24 (sealed) boiler
Speedfit one zone UFH pack
Just bought a 2 zone programmer (honeywell)

my plan was to extend to current Y system. I have attached the wiring diagram I think is right.

There is a myson MPE322 3 port valve and the plumber has just fitted a honeywell V4043H.

With this system will the UFH work independent of house CH and HW?

Any suggestions or help for a plumbing idiot would be great

Untitled

• angeldunk
• 21 Mar 2010
• 2

 

[Boilerman2]

It depends how the installer has integrated his pipework, I would expect he has piped a F&R direct to the UFH Manifold, via the 2 port V4043, it will take a person with pretty good control wiring skills to integrate the two circuits, the last one I did, involved making up a control box near the boiler to house a couple of Relays to provide independance for Heating (Rads) Heating (UFH) & Hot Water, but without visiting the site for a survey it would be impossible to guess the outcome of this one

 

[Boilerman2]

I've just had a closer look at your schemetric, it is possible that you will get a back feed via the orange wire on the Mid pos Valve which will cause problems with the existing cirucits, (I think this is why I had to fit a box of relays, to provide isolation from back feeds)

 

[picasso]

if the 3 port is/was parked on hot water only, the ufh wont recieve any flow when the 2 port opens and switches on the boiler.

 

[matt1e]

I've just had a closer look at your schemetric, it is possible that you will get a back feed via the orange wire on the Mid pos Valve which will cause problems with the existing cirucits, (I think this is why I had to fit a box of relays, to provide isolation from back feeds)

looks alright to me so Don't think that will be a problem,

if the 3 port is/was parked on hot water only, the ufh wont recieve any flow when the 2 port opens and switches on the boiler

Picasso how can you tell that without seeing the pipe layout?

Op yes the ufh will be independant

Matt

 

[picasso]

yea as usual I realised the 2 port could be installed before the 3 port as a blocking valve way to late to edit my post,

 

[kevindgas]

it rarely works !

use 3 x zone valves and do away with the mid position valve
it is usual to use 2 pumps on this type of set up 1 primary supplying all 3 zones and the 2nd running the UFH circuit the UFH also should have a mixer valve to prevent overheating

 

[Norcon]

it rarely works !

Any reason why it rarely works?
The speedfit one zone will have circulator and mixer.

 

[DeltaT]

With this system will the UFH work independent of house CH and HW.......................When the UFH is selected on it's own, where's your Sw/L for the boiler coming from?? The cylinder stat detail: what are the C NC & NO??

Depending on the valve locations, what's to stop HW circulation when selecting UFH only??

 

[matt1e]

With this system will the UFH work independent of house CH and HW.......................When the UFH is selected on it's own, where's your Sw/L for the boiler coming from??

its coming from the live terminal via the ufh 2-ports internal switch

The cylinder stat detail: what are the C NC & NO??

well brown is definitely common you would hope white is satisfied and yellow demand

Depending on the valve locations, what's to stop HW circulation when selecting UFH only??

What an awfully good point!, never noticed that myself looks like we are back in "a 3-port always having a port open" territory once again (apart from this time I totally agree with delta-t)
looks like you may have to go the 3 x 2-port route

Matt