UFH8 or UFH8N system

[Rocboni]

I recently wired a heating system with a UFH8 manifold and an unvented cylinder.... easy.

Well it threw up a few problems.

Initially I had the time clock live feeding the UFH16, ugh zone valve connected to the valve connection and fired the boiler with the volt free on the pcb LS and LR. Circ pump was from the pcb too.

Unvented cylinder was wired as you would normally, time clock and cylinder stat operating valve, valve firing boiler. High limit stat wired in too.


Heating and hot water worked fine.

Customer then complained that the stats were dead when the heating time clock was off. Which I didn't see as a problem but they wanted to look at the little digital read outs on the stats.

I returned and permanently fed the manifold, but putting the switch live from the time clock through the volt free to fire the boiler.

Problem is there was always a demand for heating so the zone valve was open, pump was running and boiler fire was on, it just wasn't firing the boiler as the time clock wasn't on.

If the hot water came on obviously water started circulating round the heating loop.

In the end I had to turn the ufh valve on with the programmer and fire the boiler and circulation pump with the orange and grey. Leaving the manifold live.

My thinking is they should have supplied me with the uh8-N or is there somthig I am missing that allows me to use all the pcb connections!

This was a plumbers house so he supplied all all the kit.

 

[DefyG]

A diagram of what you have done might help.
Sounds like a sort of S plan but over complicated it.
Are the room thermostats programmable for the UFH? as a pre-programmer is not usually required. As UFH generally never switches off a permanent feed to the manifold is always required and keeps the stats displays active.
Manifold connections for boiler (SL), pumps and valves are usually pretty obvious and some even colour coded so difficult to see how a mistake might be made there.

 

[Rocboni]

Agree its difficult to see how it can be done wrong, I'm no idiot but sometimes you miss the obvious.

 

[DefyG]

Agree its difficult to see how it can be done wrong, I'm no idiot but sometimes you miss the obvious.
View attachment 102557

That is the wiring diagram that came with the kit I presume but not the way you have connected it according to original post. I dont quite see where the volt free contacts are needed (LS & LR are not volt free), and why you need to switch the ufh valve through a programmer when there isnt a programmer in the wiring diagram, and boiler and pump through grey and orange?