Loss of Pressure - doesn't rise significantly when hot

[pjbzen]

Have a relatively new Viessmann boiler & new pump with pressurised central heating system. It was converted from vented system 2 years ago. About 10 radiators most of which are pretty new, pipes are about 30 years old.

Never seems to have really worked well, took ages to get hot and recently has started to lose pressure. When cold at 1 bar drops to about 1/4 bar over a couple of days.

Have checked all rad's and visible fittings, been under the floor and checked 90% of the pipework (10% difficult to get at - but no visible signs of leaking)...

The PRV valve isn't leaking.

I have noticed that when the system gets hot the pressure doesn't seem to increase as I've read it perhaps should?

If its at 1bar cold with boiler running up to about 75 degrees pressure might be at about 1.2bar or so? does this point to anything in particular?

Thanks

 

[ShaunCorbs]

Do you have to keep topping the pressure up (keep adding water via the filling loop) ?

 

[pjbzen]

yes top it back up to 1 bar cold every couple of days

 

[jtsplumbing]

Then you have a leak somewhere, have a look outside see if anything is dripping from safety discharge pipe.

 

[ShaunCorbs]

yes top it back up to 1 bar cold every couple of days

Can you see / noticed any valves/ trv leaking or any stains on any rads if not looks like you have a leak on your pipework

 

[thompsonbrown]

Topping up a sealed system is definitely a leak somewhere.