Underfloor heating help

dlt27 · Dec 15, 2016

Hi, hope somebody can help. I am currently wiring a new wet underfloor heating system for builder. The plumber has fitted a 2 port valve and the pump that is part of the manifold.
The existing system is a y plan.
I was going to leave existing system how it is and fit a wireless programmable stat to underfloor heating. To keep it separate I was going to fit a contactor to the switch live to the boiler
Ie from switch live of existing y plan to first A1 of 2 pole contactor and switch live from underfloor heating to 2nd A1 of contactor. This way both systems are kept seperate.
Could anybody with more experience tell me if this would work or better still another way it could be done. Thanks again

Leesparkykent · Dec 15, 2016

It wont work as a Y-plan with an additional 2 port valve as the three port will always be open in one position so when the UFH is calling it will start to heat what ever side is open as well. You need 3 x two ports , hot water, radiators and UFH.

dlt27 · Dec 15, 2016

Leesparkykent said:
It wont work as a Y-plan with an additional 2 port valve as the three port will always be open in one position so when the UFH is calling it will start to heat what ever side is open as well. You need 3 x two ports , hot water, radiators and UFH.

That makes sense now you've pointed out because obviously if underfloor is calling either the rads or hot water will be getting hot water flow from boiler. I will have to inform plumber. Thanks

Leesparkykent · Dec 15, 2016

With 3 x two ports it just gets wired as an S-plan + with the additional UFH pump

http://ww2.justanswer.com/uploads/PL/PlumbersMate/2014-09-30_082503_splanplusaddingazone3.png

The UFH pump should ideally be connected to the orange of the UFH valve through a relay so its not triggered by the other oranges from the other two valves. Some drawings show it connected to the brown of the valve but this is a bit of a bodge as the valve hasn't actually fully opened.

dlt27 · Dec 15, 2016

Could anybody explain how it would be wired or what switches what with 3x 2 port valves. Would it be wired as s plan on existing and switch the switch live to boiler through contactor as I said in first post. Thanks

Leesparkykent · Dec 15, 2016

remember if the boiler has pump over run the primary pump is connected to the pump live terminal in the boiler and not the oranges of the valves.

dlt27 · Dec 15, 2016

Thats great thanks..

Leesparkykent · Dec 16, 2016

If you get stuck list the make and model of the components and I can knock you up a drawing

dlt27 · Dec 16, 2016

What I have found is the boiler is a good distance from the controls and the control box, pump and 3 port valve are in the loft. A bit of a shoddy install to be honest.
Surelly all 3 oranges of valves will go to sw live at boiler. Or are you saying there could be an internal pump in boiler as well.Sorry only I haven't done a lot of heating wiring. Thanks

dlt27 · Dec 16, 2016

Leesparkykent said:
If you get stuck list the make and model of the components and I can knock you up a drawing

I will let you know when I go back. I appreciate your help. Thanks

Leesparkykent · Dec 16, 2016

You have the main pump and UFH pump. you only want the main pump to run when either the radiators or hot water or both are calling for heat. If the UFH is calling for heat you want the main pump and UFH manifold pump to run. To achieve this the best way is for the oranges to connect to the sw live in boiler but the orange of the UFH valve to trigger the coil on the relay which closes and fires the boiler when the UFH is calling. The UFH pump will connect to the coil with the UFH valve orange this way the UFH pump doesn't run when either the hot water or radiator valve oranges become live. The bodge way with out using a relay is to connect the UFH pump with the brown of the UFH valve.

dlt27 · Dec 16, 2016

Leesparkykent said:
You have the main pump and UFH pump. you only want the main pump to run when either the radiators or hot water or both are calling for heat. If the UFH is calling for heat you want the main pump and UFH manifold pump to run. To achieve this the best way is for the oranges to connect to the sw live in boiler but the orange of the UFH valve to trigger the coil on the relay which closes and fires the boiler when the UFH is calling. The UFH pump will connect to the coil with the UFH valve orange this way the UFH pump doesn't run when either the hot water or radiator valve oranges become live. The bodge way with out using a relay is to connect the UFH pump with the brown of the UFH valve.

Hi Lee, not sure how to message you.
Boiler is worcester greenstar 11 HE 12/22 (no overun I don't think)
I understand what your saying and how to switch ufh pump with brown of valve( pumping against dead end until valve is open). Could you explain where to get and how to wire a relay in instead. Probably simple when you explain. Thanks for your time and patience. I have enclosed a crude picture...

[ElectriciansForums.net] Underfloor heating help

dlt27 · Dec 16, 2016

I know there will be 3 x 2 ports instead of a 3 port. Thanks

dlt27 · Dec 16, 2016

Is it like this..

Leesparkykent · Dec 16, 2016

Underfloor heating help

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