Gravity hot water, pumped heating.

29 Mar 2011
Reaction score
West Midlands
United Kingdom
Hi, has anybody out there got a wiring diagram for the above system WITHOUT a 2 port valve and WITHOUT a cylinder stat. Any help would be greatly appreciated. It's just a back boiler, 3 amp switched supply, pump, room stat and a twin channel timer switched to the gravity mode.
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This shows wiring for a gravity hot water with pumped central heating system. The programmer would get its mains supply from a 3A fused connection unit (FCU)

The cylinder thermostat turns off the boiler when the hot water is up to the required temperature and the central heating isn't calling for heat. This saves energy and prevents pointless 'cycling' of the boiler. For the cost of the cylinder thermostat (£20) it's worth it. If you do leave it out, then just connect the hot water live supply straight to the boiler, and without any connection to the room stat.

The programmer will need to be one suitable for use with a gravity system, ie on that does not allow selection of central heating only.

BTW. You would have been better putting this post in the "Plumbing & Central Heating" forum, rather than in "Decorating & Painting"
Thanks for your response. It was my first post and accidently posted it in the wrong category. I understand it would be better fitted with a cylinder stat but this is a retro-fit clock only (all current wiring runs to a Danfoss 3060 in the lounge and the only piece of kit that is more than 2 feet away is the stat!) and I can't run a cable from the cylinder to the current position of the clock easily. I have completed the job today with a LP241 with a gravity jumper and a wiring center. Thanks again.

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