Ufh Zone mystery

[tennisnut]

Hi all,
Hope someone can shed light on my problem.

I've got two separate ufh zones coming off the manifold heating the lounge and kitchen respectively. Both run via wireless JG thermostats. Today I put the heating on for the first time after the summer, and only one zone will work at any time, even though both thermostats are calling for heat.

I switched the lounge one on first, heating up fine. Later switched on the kitchen, no heat. Light comes on on the receiver, so the signal from the thermostat works fine, but the zone light on the wiring centre won't come on, actuators don't respond. If I switch the lounge thermostat off, the kitchen one will then work no problem, but the lounge won't come on at the same time. What the heck is going on?

Any advice would be massively appreciated.

 

[simond]

Can you shed any light on the make and type of manifold wiring centre?

 

[tennisnut]

Thanks for your reply.
It's a JG UF3, PIC attached.

 

[simond]

Are you sure one of the thermostats is not a timer, because that would knock both out?

If you are sure that the zones aren't working correctly, the only way to check is to open up the UH3 (not UF3, by the way) and loop out both thermostats to create a demand.

 

[tennisnut]

Thanks Simon,
Though I'm afraid you've lost me.

My lounge and kitchen have separate wireless thermostats, and up until this spring (when I turned the heating off) I was able to operate both zones completely independently, but concurrently. So the lounge might be demanding heat to 22° while the kitchen was set to 20°.
Now they still work fine independently, but both zones will no longer fire up at the same time. I can only heat the kitchen while the lounge thermostat is not demanding heat and vice versa, so if both rooms are colder then desired I have to chose between heating one or the other.
One very confused lady here...

 

[picasso]

Try changing the batteries on the sender units, might not work but worth eliminating them as a cause.

 

[tennisnut]

Thanks for the reply.
In the two wireless thermostats you mean? If so, I did this yesterday, but has made no difference.