Alpha programmer +Y plan

[rabtess]

Alpha24R boiler +Honeywell Y plan.
I have had problems with CH OK but no hot water. After much investigation (including replacing the cylinder stat - unnecessary) I seem to have found that the fault is the programmer.
With both heat and HT calling, the programmer is live on both HW-on and HW-off wires from the programmer. It seems obvious that this is wrong but as the wiring and control system is so complex would some kind and knowledgable person confirm that these two wires should not be live at the same time.
I am assuming that HW-off should be live when the cylinder stat is satisfied (water hot) and HW-on should be live when the stat is calling (water cold).
I may now have to track down the Alpha 2 channel programmer or wire in an external programmer - any advice on this?

 

[stem]

When you make the tests, are you testing the outputs from the programmer with the wires disconnected? If not the live you refer to may be coming via the wire and not actually from the programmer.

 

[ianmcd]

If HW is on at programmer and cyl stat is satisfied then both HW on and HW off at programmer will be live, if the cyl stat is calling for heat then only the HW on should be live

 

[rabtess]

When you make the tests, are you testing the outputs from the programmer with the wires disconnected? If not the live you refer to may be coming via the wire and not actually from the programmer.

Yoy may have put me on the right track. I tested the output at the junction box, having disconnected the cable so there seemed to be no other source. However, to be sure and acting on your advice, I opened the boiler, loosened the programmer and removed the spade connection for HW-off - it was very difficult to remove. No current at the programmer terminal or the wire I removed. Total mystery In desperation, I reconnected the wire (HW-off) to the terminal. Now no current - something had changed. Reassembled the boiler, switched on again and the system seems to be working OK with no power on the HW-off terminals.
I don't know what happened or why it is now working. I know that electronic items are very sensitive to leakage of voltage and perhaps something like that was the problem here.
I am now waiting to see if it remains OK.
Thanks for all your help.

 

[rabtess]

If HW is on at programmer and cyl stat is satisfied then both HW on and HW off at programmer will be live, if the cyl stat is calling for heat then only the HW on should be live

Interesting piece of information - thanks. See other reply - the problem may have been fixed - or not
Thanks anyway

 

[ianmcd]

It may just have been that some Hot water was used, the supply at the HW off when the HW on is demanding is a back feed from the satisfied contact on the Cyl stat this is normal