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Postby ALAN NICOL » Tue Jun 30, 2009 10:32 am

i'm just going through an upgrade of my central heating system,i'm doing it bit by bit to get things working correctly before moving on to the next stage.
so far we've installed a new combi boiler to the upstairs of the house,and are getting a good hot water supply to the taps.
before moving onto replacing all of the old rads. we've connected the heating flow/return to supply the rads.after some jiggling around we think we've sorted out the pipe flows from the old system.
We get hot water to 2 upstairs rads,the flow from boiler gets hot,the return takes a very long time to get warm though..all other rads stay cold.system has been bled.
when draining off the water from ground floor tap,eventually hot water comes through,but when drain is shut,does not appear to carry on flowing.
One problem seems to be the single new rad in the hall has the trv on the outflow,this needs changing...but would it stop the water flow ?
Is it possible we've connected the flow/return to the wrong pipes,and would balancing the 2 hot rads,force hot water downstairs ?

any suggestions would be appreciated.
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Postby htg engineer » Tue Jun 30, 2009 7:37 pm

It doesn't matter which end of the radiator the flow and return go to - even with most modern TRV's - if you have 2x flow or 2x return going to one radiator it'll not work.

You could try turning off all but one working radiator and one that is struggling to see if it works (the reason I say 2 instead of the normal 1 - is that if you have piped it up wrong the pump will be pumping against itself)

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