Gravity fed system - Is Heating Only possible?

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Below is a description of my Central Heating system:
- Gravity fed system
- Baxi Bermuda Back Boiler 552
- coil type double feed indirect cylinder (Dublotank 100)
- Salus EP200 programmer twin channel
- Sunvic TLM2253 wall thermostat
- Sunvic MK1453 3 port valve with DM5601 actuator
- RJ2802 Relay Wiring box
- Grundfos UPS 15-50 pump

Recently I had to replace Sunvic MK1453 3 port valve and the DM5601 actuator (the whole story why is available from //www.diynot.com/forums/plumbi...more-dm5601-or-mk1453-or-ep200-faulty.347556/)

Until now I assumed that with my system, heating only was not possible (i.e. hot water is automatically turned on when the heating is turned on). But after repairing the RJ2802 Relay Wiring box, I noticed that no wire were connected to the HW Off (i.e. pin 18 ) of the junction box.


Therefore I connected a wire between pin 1 (i.e. HW Off) of the Salus EP200 programmer and pin 18 of the RJ2802 Relay Wiring box. I would have thought I should now be able to have heating independently from hot water, however from the programmer I am still unable to select heating only. Each time I turn the heating on, hot water is also activated.

With a gravity fed system, shall I be able to select "Heating Only"?

There is a jumper at the back of the EP200 programmer, it is currently set as Gravity. Shall I move the jumper to the "Fully pumped" position? What are the implications if I do so?
 
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I connected a wire between pin 1 (i.e. HW Off) of the Salus EP200 programmer and pin 18 of the RJ2802 Relay Wiring box.
You also need a wire between terminal 2 of the HW stat and terminal 11.

Shall I move the jumper to the "Fully pumped" position?
Yes

What are the implications if I do so?
It will work. :LOL:

You have a fully pumped system, not a gravity HW/pumped CG system.
 
Thanks for the quick reply. I have moved the jumper of the EP200 to the "Fully pumped" position, did a reset of the programmer and now I can turn on Heating Only.
 

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