Adding wet under floor heating to a Y plan

[Top Cat]

Hi as i am a new guy i can't do a diagram so will have to explain.

Have just done a job for a plumber adding a wet under floor heating system to a Y plan heating system.

I have got a time clock operating a new 2 port Honeywell motorised valve.

When the time clock is calling for heat the valve opens. I have a permanent live on the grey wire and have linked the orange wire to the orange of the existing 3 port Honeywell valve.

This appears to work but am still having a few problems so do not know if it is electrical or plumbing.

Hope i have expained it OK.

Cheers

 

[PC Electrics]

Hi as i am a new guy i can't do a diagram so will have to explain.

Have just done a job for a plumber adding a wet under floor heating system to a Y plan heating system.

I have got a time clock operating a new 2 port Honeywell motorised valve.

When the time clock is calling for heat the valve opens. I have a permanent live on the grey wire and have linked the orange wire to the orange of the existing 3 port Honeywell valve.

This appears to work but am still having a few problems so do not know if it is electrical or plumbing.

Hope i have expained it OK.

Cheers

So, what problems are you having?

 

[Top Cat]

The boiler starts up and pump but under floor heating does not get hot, (although the pipes are hot up to the new motorised valve) it seems to be pumping the wrong way up the return and back down the flow and not through the motorised valve even though it is open. This seems to rectify itself when the main central heatig is turned on.

 

[PC Electrics]

Is the 'take off' for the ufh before the 3pv or after the 3pv on the heating side?

 

[Top Cat]

I think it is after but was not taking much notice as plumbing is not my strong point!

 

[PC Electrics]

In that case that's wrong. If the take off for the ufh is after the 3pv then the ufh cannot get any water untill the main heating is on and the 3pv is open on that port.

TBH the system should have been converted to an S plan plus. If the original section really must remain as Y plan, then you need two 2pv's anyway and the take off for the ufh should be before the 3pv with a 2pv to close off feed to the y plan because a 3pv never actually closes off (one port is always open, which port depends on the signals it recieves and what it was doing last).