we recently had one of our radiators taken off the wall to replaster behind. When it was taken off, it leaked a lot of water due to a broken valve. The guy doing this work said our central heating was unusual as it was gravity fed. He replaced the valve but said when we want to put our heating on we should make sure there's water in the system first or the boiler will have nothing to work on and may break.

So my question is - how do I get water into the system in a gravity fed central heating system where one radiator has emptied itself? Thanks Claire

  • Most systems are self-filling but you need to bleed trapped air out of the top of each radiator. Not certain about yours. – keshlam Oct 6 '16 at 8:26
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    Gravity or pump-fed it doesn't matter. The thing that matters is what kind of expansion tank do you have: Is it classic open-type mounted at the top of the house or a modern diaphragm/membrane type mounted near the furnace? Open types usually have a floating valve just like a toilet tank and self-fill as keshlam said. Or you put in a hose and fill it manually from tap. Circuits with diaphragm tank usually have a crossfeed valve that connects your heating circuit with mains, so you just open it for a short time. – Agent_L Oct 6 '16 at 10:28
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    Any plumber should be able to show you how to refill your system. To me, "gravity-fed" just means there's no circulator pump, so the only thing moving water around is the density difference between hot and cold water. Just to be clear - is this a hot water system or a steam heat system? – Carl Witthoft Oct 6 '16 at 17:28

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