Pressure dropping to 0 on new combi boiler

thor

I have an 14 year old Vaillant ecomax boiler(don't know if it is combi or condensing type) and it's pressure drops to zero in a matter of a few weeks despite there being no visible leaks. The funny things is that I can't be bothered repressurising it anymore as I have found that it makes no difference to the running of the CH system. It must be nearly a year now that even though the pressure guage has been showing below 0 bar, the hot water and CH have been working flawlessly.

macman

Ash5ley wrote: »

The plumber came today and turned off a couple of vales to check if pressure will drop.

There is no water in the pressure relief valve outside.

The water will be on the ground below the discharge pipe, not 'in the valve'. You need to tape a plastic bag over it to make any discharge visible before it evaporates.
Has your RGI checked the EV pressurisation? If not, it's time to get a new one (RGI, not EV).

Annie1960

macman wrote: »

As stated in post 2, it could equally be venting from the PRV overflow pipe, go outside and check. Or the EV may be faulty and need repressurising. There is no basis for your installer to assume it's a leak on the CH circuit until he has checked the first two out, which would take just a few minutes.

These appear to be the most common causes, and when my combi pressure kept falling recently these were replaced. The problem remained exactly the same.

Turned out it was a blocked flexible hose in the boiler. Once this was replaced, the boiler worked fine.

shays_mum

We had a a similar prob when we installed our new boiler. Numerous engineers visits later, even my friend who's a BG engineer could not find out what the problem was. In the end after pulling the floorboards up, we discovered 2 separate leaks around the house.
Soon as they were sorted, everything was ok.
Hope you get it sorted soon op!

crazylady100

I have just seen this old thread as I have been having similar problems with my boiler losing pressure and the boiler engineer couldn't find where the leak was. We thought it might be under the tiles in the hall but the last thing I wanted was to start ripping the floor up to find the leak with all the expense and disruption that goes with that.
It turns out that the cost of finding the leak was covered on our insurance policy under what they call Trace and Access (trace the leak and access it). There are companies that specialise in this work and they find the leak by using a special heat camera and by introducing a special gas to the system which they then sniff out with a detector. We used a company called The Leak Team and they were able to pinpoint the leak to a pipe under the corner of the lounge, which is carpeted and therefore easy to pull back and fix. Much less disruption than hacking up the hall tiles and they found the leak on the first visit, which was such a relief after all the tooing and froing we had had already with plumbers etc.
I recommend that you check your insurance policy to see if you are covered for this sort of work. Having said that the company I used were so confident they would find the leak they said there would be no fee if they couldn't!

pollypenny

Our pressure fall was caused my over-energetic hoovering.

I'd bashed one of the pipes, causing a crack just below the floor. It was by my bed and my book pile.