Y plan system, CH only comes on when HW also on.

[St0rmer66]

Hi All. Well, I have established there is indeed a 240vAC signal on a pin 1 under the following conditions:- Both HW and CH off, and CH only on. Under other conditions (CH + HW, HW) the voltage on pin 1 drops to zero. So it's either a break in continuity or the wrong wire.

Nothing wrong - that's exactly how it should behave. So rule out the programmer.

 

[D_Hailsham]

Hi All. Well, I have established there is indeed a 240vAC signal on a pin 1 under the following conditions:- Both HW and CH off, and CH only on. Under other conditions (CH + HW, HW) the voltage on pin 1 drops to zero. So it's either a break in continuity or the wrong wire.

Can we be clear about this?

CH OFF and HW OFF = 240V on pin 1
CH ON (and HW OFF) = 240V on pin 1

If I have understood that correctly, it's the expected result.

HW ON and CH ON = 0v on pin 1
HW ON (and CH OFF) = Ov on pin 1

If I have also understood that correctly, it's as expected.

So there must be a broken/missing wire between programmer and junction box.

Have you managed to find out what the spare red wire, junction box - right, does?

 

[chillyfly]

Good news! I followed the black wire in the junction box by the valve along the twin core cable back to the roomstat downstairs. (The signal from the roomstat was coming in on the same cable) and lo and behold, after removing the front of the roomstat and unscrewing it from the wall box, there was a black wire dangling, with a bare end not connected to anything. And just next to it was another black wire, also bare ended, and also hanging loose, that had 240vAC on it when the CH was selected on, that dropped to zero when the HW was turned on also! Result! The two are now connected and insulated, and I now have a perfectly functioning Y-plan system again!

And a spare 3 port valve!

If the previous owners are correct, it has been like that for the last 14 years.

Thanks again for all the help. A simple wiring fault all along, with no signal to turn the HW off, as you suggested.

 

[DP]

Good news! I followed the black wire in the junction box by the valve along the twin core cable back to the roomstat downstairs. (The signal from the roomstat was coming in on the same cable) and lo and behold, after removing the front of the room star and unscrewing it from the wall box, there was a black wire dangling, with a bare end not connected to anything. And just next to it was another black wire, also bare ended, and also hanging loose, that had 240vAC on it when the CH was selected on, that dropped to zero when the HW was turned on also! Result! The two are now connected and insulated, and I now have a perfectly functioning Y-plan system again!

And a spare 3 port valve!

If the previous owners are correct, it has been like that for the last 14 years.

Thanks again for all the help. A simple wiring fault all along, with no signal to turn the HW off, as you suggested.

I must be thick.
I thought with HW on, CH would work as well, but no CH with HW off
What has the full travel of mid position valve got to do with room thermostat? Also, there should be three wires (and earth if it is required) on majority of room thermostats that have an anticipator fitted. Connmections to said roomstat would be N, Eth, Live and Switched Live
I am well confused now

 

[chillyfly]

Didn't mean to confuse by talking about the roomstat. I was trying to find the break in the HW off signal. The other wire in the same piece of electrical flex at the junction box was wired to the roomstat, so I suspected I might find the other end of the black wire there too. Another black wire to the controller HW off signal was there too. Neither were wired to the roomstat and we're never meant to be, I guess it was just the easiest way to wire the controller pin 1 to the valve, by joining the two ends by the roomstat.

 

[DP]

Chilly fly I am still confused but if your controls work now, well done

 

[D_Hailsham]

Good news! I followed the black wire in the junction box by the valve along the twin core cable back to the roomstat downstairs.

Well done! But I bet you wished you had traced that wire earlier.

 

[chillyfly]

Good news! I followed the black wire in the junction box by the valve along the twin core cable back to the roomstat downstairs.

Well done! But I bet you wished you had traced that wire earlier.

I sure do! At least it's working properly before the chap installs Hive...