help with pressure problem

[philstannard]

Hi hoping someone can help!

I have a pressurised central heating system which heats my radiators and hot water cyclinder, via an oil run boiler. The system is 3 years old, this summer i drained the system fully as i was removing numerous radiators to decorate. I have since refilled the system and am experiencing a major problem. I set the pressure at 1.5bar as recommended by the original fitter of the system, but this pressure falls by at least 0.4 bar a day, thus i am filling the system daily via the filling loop to keep water in the system and to keep the pressure up. I have checked the system for water leaks and as of yet am unable to find any. I placed an empty bottle under the release pipe which comes from the pressure vessel but this has remained empty. I have to keep bleeding the upstairs radiators and the one which is nearest the bolier/pressure vessel. I am concerned due to the large pressure drop and the amount of water i must be losing?

Any ideas?

Thanks

Phil

[Gav]

start by bleeding rads bottom to top (downstairs to up), look at the blow off( on the outside of building) to see if there is evidence of water

[philstannard]

I've bleed all the radiators and have been checking the blow off since the problem began and there is no sign of any water.

[John Stumbles]

Have you got inhibitor in the system? If you're bleeding the system then not only is pressure dropping but air or other gas is getting in. The gas could be due to corrosion. Of course if you're losing fluid _and_ refilling it then the original corrosion inhibitor will be getting diluted. If it was a certain cheap brand it probably wasn't effective in the first place (google...).

Does the pressure rise greatly when the system is hot? You've done the right thing to check for discharge via the PRD.

Do you have copper CH pipes buried directly in floor screeds or passing through brick walls without protection around the copper? They could be corroded and leaking - especially if you've disturbed them by working on the system replacing rads.