Combi-Boiler Pressure Drop

[greenrook]

Hello All, I keep having to re-pressurize my central heating combi boiler (about once a fortnight) and I remember there used to be some jollop available from plumber's merchants, which when introduced into a conventional c/h system via the header tank, would find small leaks and bung them up. Can you do this with a combi, and if so, how? Or any other suggestions? I'll be very grateful. -G-

[The Builder]

Before you pour any goo into the system, it would be worth having someone re-charge your pressure vessel. Of course there may be a small leak somewhere, but I would try this first.
The vessel usually has a small "schrader" valve sticking out of it. The same valve that you find in a car tyre or bicycle. A standard footpump will re-pressurise the vessel. If the charge doesn't hold, it's possible the vessel has ruptured and needs replacing.

[deggers316]

could be the pressure relief valve, is there any water dripping out of your outlet pipe which will be on the other side of your combi boiler outside,if there is nits the pressure valve not a long or expensive job around £30 fitted

[sherrardk]

Have you got a leaking radiator (I have, it's really sneaky about it).

[greenrook]

Thank you, Gentlemen all.
No, no leaks from rad valves or bleed valves, no suspicious wet patches anywhere else, and no dripping from the relief valve pipe outside. The pressure vessel is an exterior one, sitting on a nearby shelf, so I'll see if I can borrow a foot pump and recharge it somehow. Thank you all for your help. -G-