I have installed a four zone system, but I have made what appears to be a school boy error. Basincally, I have three CH zones, upstairs, downstairs and conservatory, and a DHW zone, all connecting back to a common return. However, when the downstairs CH is selected, the upstairs rads slowly come on as well. I seems that at one of the upstairs radiators, the returning downstairs CH passes through the upstairs radioator via the return, thereby pressusing the supply side of the upstairs rads! Should I have fitted check valves on every radiator (or at sensible places on the return system) to prevent this? Can I get a combined non-return/lockshield for each radiator? Any ideas appreciated!
check valves in heating system?
- Thread starter D4dog
- Start date
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You should be looking at the piping and not check valves. 
Cant see anything wrong with the pipework. Zone valves on each supply leg, but common return. The only way to stop this would have been to have had seperate returns all the way back to the boiler - neither practical nor economic, surely?
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Logic would suggest that if the pipework was 100% correct, the system would function 100% correct. I have never seen a system that was piped up correctly where there was a need for check valves. Maybe Bahco is right.
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