Advice on a JG UH3 Wiring Zone and how to stop the UF pump running when the HW timer kicks in

[hantsgaz]

Hi all. First post. I have a JG UH3 wiring zone and I've noticed that the UFH pump always comes on when the HW 'circuit/thermo' is triggered. Hence - rather than just heat the water in the tank - I also heat the UF circuits.

I can't see a way to avoid this - it may be the way the circuits work on the UH3 (as in the pump always comes on) .....

So wondering if anyone has any insights on this? My HW timer is wired to Zone 1 on the UH3, via a thermostat on the HW cylinder (providing the SL- I guess). It may be that I just need to add some actuator valves to the UF circuits to stop them being heated - but the pump will still run. So wondering if that is a solution and it's ok? I'd prefer to stop the UFH pump running completely - but if it's OK to just fit actuators then I'll do that. Many thanks.

 

[Deleted member 120897]

Is the ufh zone a separate zone from the hot water?

 

[hantsgaz]

Is the ufh zone a separate zone from the hot water?

Hi - yes it is. I should also have said that the pump comes on regardless of what thermostat or timer triggers the boiler into action. So even the when the rads (again on a different zone) come on, the UFH pump is active. Thanks.

 

[ShaunCorbs]

Move the pump to the ufh port valve orange connection

 

[EvilDrPorkChop]

Without sounding daft, there's a dedicated UFH Pump connection on the JG UH3 wiring centre.....

 

[hantsgaz]

Move the pump to the ufh port valve orange connection

Good call. The pump has an earth connection that's currently connected to the earth terminal of the pump on the wiring centre and the UFH zones don't have an earth. Should I just leave the earth cable where it is then? And I connect the pump's live to the SL of the UHF zone I guess?

 

[ShaunCorbs]

Yes that’s fine

 

[hantsgaz]

Without sounding daft, there's a dedicated UFH Pump connection on the JG UH3 wiring centre.....

Yes and that's where my UFH pump is currently wired. However, no matter what sensor/thermostat triggers the boiler into action (e.g. rads, hot water, UF heating) the UFH pump comes on - which is issue I'm trying to resolve. E.g. if the rads are triggered (via timing or temperature) the system also heats the UF zones as UFH pump comes on. Same if I just want to heat the water in the tank - the UFH pump comes on.

 

[EvilDrPorkChop]

Yes and that's where my UFH pump is currently wired. However, no matter what sensor/thermostat triggers the boiler into action (e.g. rads, hot water, UF heating) the UFH pump comes on - which is issue I'm trying to resolve. E.g. if the rads are triggered (via timing or temperature) the system also heats the UF zones as UFH pump comes on. Same if I just want to heat the water in the tank - the UFH pump comes on.

Then wiring the pump into the UFH zone valve will make no difference, as the wiring centre will open the zone valve when it runs the UFH pump.

Are you using zones on the UFH wiring centre for the rads and HW? If so you either need to wire them separately or buy a newer wiring centre.

 

[hantsgaz]

Then wiring the pump into the UFH zone valve will make no difference, as the wiring centre will open the zone valve when it runs the UFH pump.

Are you using zones on the UFH wiring centre for the rads and HW? If so you either need to wire them separately or buy a newer wiring centre.

Then wiring the pump into the UFH zone valve will make no difference, as the wiring centre will open the zone valve when it runs the UFH pump.

Are you using zones on the UFH wiring centre for the rads and HW? If so you either need to wire them separately or buy a newer wiring centre.

Answer to your second sentence first: I have my rads on one zone (z8), HW on another (z1) and two UFH zones (z2&3).

First sentence: Hmm, ok. Trying to process this and have to confess I don't follow what you are implying here. Probably as I'm not sure what the UFH Valve is doing / does as the Gr and Or terminals are bridged at the mo (I guess factory fitted) and nothing is wired to the L, E or N terminals. Thanks

 

[hantsgaz]

Yes that’s fine

Just realised (due to other post) what set of terminals you were talking about! There is an UFH Valve zone too (I was thinking you were referring to the Thermostat zone) - and the UFH Valve Zone has L, E, N, Or and Gr terminals! Currently the Or and Gr are bridged - I'm guessing factory fitted. So were you suggesting just moving the pumps L wire to the Or terminal on the UHF Valve 'zone'? Thanks.

 

[ShaunCorbs]

Do you have an ufh zone valve as it sounds like either you don’t or it’s not wired there / correctly

You should have 3 2 port valves

 

[hantsgaz]

Do you have an ufh zone valve as it sounds like either you don’t or it’s not wired there / correctly

You should have 3 2 port valves

No I don't have an UFH valve or actuators.

 

[ShaunCorbs]

No I don't have an UFH valve or actuators.

So it’s not on its own separate circuit hence why your having issues needs re plumbing with 3 x 2 ports eg hot water, ch, ufh if you have a cylinder

 

[hantsgaz]

So it’s not on its own separate circuit hence why your having issues needs re plumbing with 3 x 2 ports eg hot water, ch, ufh if you have a cylinder

 

[hantsgaz]

That's basically my set up. Less the cross-throughs. Hopefully that makes sense now. All different components (e.g. rads, HW, UFH on separate zones). But no UFH Valve.

 

[ShaunCorbs]

Do you have rads as well or just ufh?

 

[hantsgaz]

That's basically my set up. Les the cross-throughs.

Do you have rads as well or just ufh?

Yes - rads on z8. UF on z2&3. HW on z1.

 

[ShaunCorbs]

Can’t have hot water on z1 as these all bring the ufh pump on

How are you controlling hot water ?

 

[hantsgaz]

Can’t have hot water on z1 as these all bring the ufh pump on

How are you controlling hot water ?

That's what i thought originally - the way the UH3's circuit board is programmed - all the zones bring the pump on.

 

[ShaunCorbs]

Do you have a timer on the hot water ?

 

[hantsgaz]

Can’t have hot water on z1 as these all bring the ufh pump on

How are you controlling hot water ?

The same way as the diagram shows.

 

[hantsgaz]

Do you have a timer on the hot water ?

yes

 

[ShaunCorbs]

Vis a jg room stat ?

 

[hantsgaz]

Vis a jg room stat ?

No. A Drayton LP711

 

[hantsgaz]

Just realised I crossed out the rads thermostat on the previous diagram.

Also there is no B2 wired connection from the HW timer (Drayton LP711).

 

[EvilDrPorkChop]

Basically you can't do what you're wanting to do with that Wiring Centre. You either need to rewire the HW & Rads separately from the UFH wiring centre or upgrade your UFH wiring centre to a model that allows you to have HW and select if zones are part of the UFH circuit (Think the new JG Speedfit one will allow you to do this)

You also need actuators or a motorised valve on your UFH circuit.

 

[hantsgaz]

Basically you can't do what you're wanting to do with that Wiring Centre. You either need to rewire the HW & Rads separately from the UFH wiring centre or upgrade your UFH wiring centre to a model that allows you to have HW and select if zones are part of the UFH circuit (Think the new JG Speedfit one will allow you to do this)

You also need actuators or a motorised valve on your UFH circuit.

Thanks -thought that might be where I'd end up. I get the actuators part, but if I fit those - what extra does the motorised valve for the UFH heating circuits give me? Thanks.

One other question if I may - what does the Yes/No switch on the wiring centre actually enable? I don't quite understand the words 'if set to no zone 8 is isolated' part. Isolated from what - the rest of the boards functions? The full text on the board reads 'If set to yes Zone 8 enables the boiler, pump and valve. If set to no Zone 8 is isolated'. Thanks again.

I wish the previous owners left the UH3 manual! Can't find that online anwhere!