HI SILLY QUESTION REALLY


Postby daveyjones » Wed Sep 22, 2010 5:32 pm

hi someone asked me the other day if my system is a gravity system how do i know lol sorry for rubbish question and also in my friends flat he is relacing the combi filling loo is it just any i buy and do i just turn water to the proerty off and relieve ressure at the boiler??

thanks
david
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Postby plumbbob » Fri Sep 24, 2010 8:22 pm

Gravity refers to the way the hot water cylinder is heated.

Fully pumped systems have 22mm flow and returns from the boiler and both the hot water supplies are pumped.

In a gravity system, the central heating is pumped as above, but the boiler has an additional two 28mm pipes connected which uses the principle of hot water rises (gravity) to heat the DHW cylinder.


The pressure in a combi is for the heating side only and has no connection whatsoever with any other water usage. You only drop the pressure if you need to work on a radiator.

Anything else, just turn the main stop tap off.
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Postby htg engineer » Sun Sep 26, 2010 4:02 pm

'The pressure in a combi is for the heating side only and has no connection whatsoever with any other water usage. You only drop the pressure if you need to work on a radiator.'

and the non-return valve on the filling loop, if you do not at least and isolate the boiler, you'll get very wet.


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