HW always comes on with CH on Siemens RWB29

[Barneyjoe]

Hi Folks,

Recently replaced old controller (very noisy Drayton SM2 rotary dial) with RWB29 and quite happy. I noticed this morning though, that when I tried to advance just the CH, the water always comes on as well. I checked the interwebs and reset the controller as suggested to no avail.

I am sure this wasn't the case with the old controller and they both use the same standard backplate.

After a reset, I changed prog so CH came on at a different time to HW. When CH switched on, the HW came on again even though it should have been off.

I have set the dip switches for 5/2 gravity fed system.

Any ideas?

 

[twgas]

Gravity HW must be on when using heating, unless you have a valve on the HW return

 

[denso13]

For a gravity system it is normal that with the CH on the HW will also be on. Are you sure you have a gravity system? It doesn't matter if it is gravity fed but rather if the HW system works by gravity. Do you have any zone valves on the system?

 

[Barneyjoe]

Mick and Denso,

I am sure that wasn't the case on the old Drayton, but I think I'll have to re-install it and check. It might be that the system is pumped and I'll check the settings on the old one.
I think you might be onto something so I'll check this out. Thanks for redirecting my thoughts!

 

[Barneyjoe]

Simples! Thanks for that. I reset the dip switch to a pumped system after comparing the old unit settings and it worked. Should have thought of that before installing so thanks again for pointing me in the right direction.
Brendan