Drayton Wiser Gravity system

28 Sep 2023
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United Kingdom
I was about to change my Drayton LP722 to a Wiser model but just discovered the Wiser does not cater for gravity systems.

Although the water heating is theoretically gravity, because of the distance and height difference between boiler and hot water tank it needs to be pumped to circulate enough. I have a thermostatic valve on the hot water tank and always just used the central heating settings to provide heat to both water and radiators. In summer, when the heating is not in use, the hot water is heated by electricity.
So basically I don't need any actual control of the hot water, it just gets heated as a by-product of the central heating.

The wiring on the backplate has two switched live connections, HW (boiler) and CH (pump).

On my old controller there was a link that could be set for gravity systems, which would switch both these connections on if CH was called for, thus firing the boiler and switching on the pump.

On the Wiser, would connecting both HW and CH wires to the CH terminal work (as I don't need HW control) or would this be too much of a current draw and necessitate a relay of some sort?

Your thoughts would be gratefully received.
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No you need to add either two zone valves (S Plan) or one mid position valve ( Y plan) if you want to use the Wiser system
Thanks, one thing I should have said is that the boiler is in a detached garage, some distance from the house. I am trying to use the existing wiring so not sure how to provide the power to the boiler if I have to keep HW and CH feeds separate. As I mentioned, the old controller would power both terminals when CH was called for.
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Have you thought about other systems?
I believe it should be controllable from a Hive with a setting change, or Nest, with some wiring changes...

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