is it okay to close the gate valve on radiator pipework?

29 Oct 2007
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United Kingdom
i had a problem with the central heating, the one in the back bedroom and also in the kitchen and bathroom would not get very hot they are on 8mm pipework return and flow, the downstairs front room and the backroom are on 15mm return and flow

the flow pipe would always be hot but the return would only be luke warm i tried balancing the system with no luck

so i ripped out the floorboards in the back living room near the radiator, i noticed the 22mm flow and return pipes which were then connected to 15mm flow and return pipes and a gate valve connected to the 15mm return and flow pipes the gate valve was fully opened, the gate valve and the radiator is directly against the boiler which is in the kitchen so i closed the gate valve as soon as i had done this the kitchen, bathroom and back bedroom radiators were becoming much hotter

upstairs radiators are connected on 8mm but i believe they are also partially connected on 15mm under the floorboards

is it okay having the gate valve fully closed? because now all my radiators are just as equally hot, would this affect my CH system or boiler in anyway?

the only thing i have realised now is that i have noticed a hissing/humming sound coming from the radiators but if i open the lockshield valve fully then the noise slightly dissapears and radiators are still equally hot

please could you advise if the above is okay
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This gate valve has been fitted as a by-pass. Close this then open it about 1/4 to 1/2 a turn. This should be ok.

It is there for the pump to have somewhere to pump if you have TRVs and they all shut together
hi gas4you, i have fully closed the gate valve and put the floorboards and the laminate flooring back down again!!! :rolleyes:

would this be a problem? would it affect the boiler or pump in anyway? whats the humming noise coming from the radiators?
Could be too much resistance from the rads and the pump being too restricted.
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Replace the gate valve with an automatic bypass and set it correctly. it may not solve the problem, but you need a bypass anyway and it will improve the working of the system even if there are other issues.
Did you feel the gate lift or did you just take up the slack.

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