just had some work done on central heating yesterday (pump replaced, 2 auto bleed air vent things fitted in loft, and 2 radiators desludged). Anyway the pressure on the gauge is dropping slowly, and had to add more water from the filler loop this morning.

Cant see any obvious leaks, but heating has been on so any slight ones are probably evaporating as soon as the water leaks out.

Anyway, i’m sure someone once told me that little leaks often seal themselves after a few days (? due to residues left after water evaporates from the leak), or is this a load of rubbish and should i get the plumber back straight away?

thanks

first port of call should be the expansion tank.

I have a service contract with British Gas and I was very glad I did – it took about 5 visits in the end to fix the same sort of problem. Basically, fixing the initial problem seemed to tweak other seals and they were just a nightmare to stop leaking…

Its possible its auto bleeding air out of the system in phases, reducing volume and hence pressure. Are all radiators bled?

It should obviously stop bleeding once all the air in the system has escaped via the auto bleeders. Are all the rads getting hot?

If its not air leaving then it’s water. Check all the joints that he’s worked on for dampness.

Have a look to make sure you;ve not got air in the system. It could be auto bleeding. It might be worth manually bleeding all the radiators.

You could turn the heating down and let it run as this may give you more chance to find the leak.

After this I would get the plumber back. If it is a leak and you can’t find it the next thing you may find is damp marks on the ceiling.

i’ll have a good look at all the joints tonight before the heating heats up and bleed all the radiators then keep an eye on the pressure before ringing him back.

How do those auto vent things work? Just looked like a lump of brass with a black plastic ‘bung’ in the side and a little plastic screw cap on the top (which was loose, i assume this is to let it auto vent?)

yep. leave it loose to vent.

They look after themselves, although I have a couple that suffer from hard water deposits.

They let the air out of high points as it collects there when the system is circulating.

However if air is stuck at another high point then it may take some time for all the air in the system to get out.

I found a slight leak in my magnaclean yesterday. Since the pressure was reduced I took the chance to clean it. By ‘eck it pulled a mahoosive amount of iron filings out of the water. Tightened it up again and repressurised, bled the radiators, did it again and it now seems OK.