Problem with boiler - loosing water pressure

anna2319

Hi everyone,

I'm new on this forum although I've used the website on a regular basis. I can see are loads of posts on this site and a lot of people sees it every day. I wonder whether anyone had a similar problem and could help me ...

We have a Worcester Bosch combi boiler at our home. It's approx. 4 years old and there was never any problems with it. However, we've noticed that there is a problem with water pressure. Basically it just dropped to the red area to 1 bar so we've topped it up with water to recommended limit. Surprisingly it took only approx. 10 seconds to get to the right level. Once it's been done, the pressure went down next time the boiler was on. We've been topping up the water every single day now and it's the same every time.

We've checked all radiators - no trapped air. Also no leaks anywhere. We've checked the pipe that goes outside the house as well.

Does anyone has any idea what could cause this problem? I looked on other forums and found out it might be the Pressure Relief Valve, but why does the pressure go up so quickly when we add some more water?

Fluff15

If you are sure there are no leaks, then it may be that the expansion vessel needs recharging or replacing. Generally there would be a leak from the overflow pipe or boiler if the PRV is letting by.

Ask around for a local, reputable gas safe engineer to have a look.

SGM1

Depending on how large the system is it won't take long to put some pressure in. If the expansion vessel is flat, which is most likely the cause of the problem it's not a true reading anyway. You would want to get this looked at quickly, if the PRV starts to let by they can be a nightmare to clean/change. If there is no water dripping for the overflow outside it is fine at the moment, probably the vessel just filling with water so will need tobe recharged

Agrajag

Yes, it sounds like the expansion vessel is failing, so when the water heats up, the pressure in the system increases a lot (normally would be dealt with by the expansion vessel). Instead some water is released out of the overflow pipe.

This will not be a huge amount of water (it takes very little to reduce the pressure, so you may not see it happening. A great tip is to attach a plastic bag to the end of the overflow pipe (with an elastic band). Then if water is being released, it will be collected and visible.

If this is happening, call a plumber, tell them what you have found, and suggest the expansion vessel may need replacing (so that they can bring one with them if possible).

Seronera

Correct everybody. Get the Pressure vessel checked and recharged. Just hope its not the PRV on a Worcester Bosch. Their designers play this game called 'Hide the PRV in the least convenient place...right round the back..facing the wall. Its part of their bonkers design philsophy.

Seronera

SGM1

Agrajag wrote: »

Yes, it sounds like the expansion vessel is failing, so when the water heats up, the pressure in the system increases a lot (normally would be dealt with by the expansion vessel). Instead some water is released out of the overflow pipe.

This will not be a huge amount of water (it takes very little to reduce the pressure, so you may not see it happening. A great tip is to attach a plastic bag to the end of the overflow pipe (with an elastic band). Then if water is being released, it will be collected and visible.

If this is happening, call a plumber, tell them what you have found, and suggest the expansion vessel may need replacing (so that they can bring one with them if possible).

I'd be very surprised if it needs replacing already. Probably just recharging, don't want to give ideas to people that can cost you a fortune