Underfloor heating help

[dlt27]

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]

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]

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]

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]

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]

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]

Thats great thanks..

 

[Leesparkykent]

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

 

[dlt27]

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]

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]

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]

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...

 

[dlt27]

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

 

[dlt27]

Is it like this..

 

[Leesparkykent]

 

[dlt27]

.

 

[dlt27]

That looks a bit better than mine. Thank you again. All makes sense now.

 

[Last plumber]

If you are altering this to an S Plan, you need to make sure you have an auto bypass installed. There may already be one but I thought I'd mention it, it should have one anyway really but not everyone installed them on a Y plan

 

[dlt27]

Ok. Thanks