Bloody boiler

[gsgsgs]

I have a combi boiler, over last week or so it loses pressure (the pressure gauge drops). I can turn two taps that I assumes adds water to the system and the gauge goes back in to the green segment. I've had 24/7 (don't get me started on them) twice, they've replaced a reservoir but that hasn't solved the problem. Due to the time of year, work etc I'm struggling to be in until the new year for a 3rd visit from 24/7. The boiler works, I have heating and hot water, any Qlocal boffins know it it's OK to leave the way it is, in me filling it every day or so until I can be in.

[Blackrock]

I have a combi boiler, over last week or so it loses pressure (the pressure gauge drops). I can turn two taps that I assumes adds water to the system and the gauge goes back in to the green segment. I've had 24/7 (don't get me started on them) twice, they've replaced a reservoir but that hasn't solved the problem. Due to the time of year, work etc I'm struggling to be in until the new year for a 3rd visit from 24/7. The boiler works, I have heating and hot water, any Qlocal boffins know it it's OK to leave the way it is, in me filling it every day or so until I can be in.

I'm not a boiler / gas engineer but it strikes me that if you are having to get the pressure up all of the time by adding more water, then it must be leaking somewhere? I don't know how to fix it but have you checked all around the system (radiators, pipes etc) for leaks ?

[Rigsby]

I have a combi boiler, over last week or so it loses pressure (the pressure gauge drops). I can turn two taps that I assumes adds water to the system and the gauge goes back in to the green segment. I've had 24/7 (don't get me started on them) twice, they've replaced a reservoir but that hasn't solved the problem. Due to the time of year, work etc I'm struggling to be in until the new year for a 3rd visit from 24/7. The boiler works, I have heating and hot water, any Qlocal boffins know it it's OK to leave the way it is, in me filling it every day or so until I can be in.

It’s one of two things.

As you suggest, a leak, this could be a small weep that could prove extremely difficult to find if in an hidden location.
You should avoid the use of “leak sealer” additives if at all possible.

The second would be a failed / faulty expansion vessel. An expansion vessel is a empty vessel with a rubber membrane splitting it in two internally, one side charged with air the other holds water from the CH system.
As the water heats up it expands, water can’t compress so it pushes on the membrane and compresses the air on the other side, when it cools it returns to its previous state.
If the membrane has formed a small leak it will allow the water to pass into the section where the air is, reducing the system pressure and reducing the volume of area for expansion.

In some cases the air side can be recharged by using a bicycle pump, but if the vessel has failed it will need replacing.

[Rigsby]

Have a look on DIYnot.com and go to Forums, Plumbing and Central Heating section.

There is loads of really good help and advice on there, mostly from tradesmen.

[silver fox]

I have a combi boiler, over last week or so it loses pressure (the pressure gauge drops). I can turn two taps that I assumes adds water to the system and the gauge goes back in to the green segment. I've had 24/7 (don't get me started on them) twice, they've replaced a reservoir but that hasn't solved the problem. Due to the time of year, work etc I'm struggling to be in until the new year for a 3rd visit from 24/7. The boiler works, I have heating and hot water, any Qlocal boffins know it it's OK to leave the way it is, in me filling it every day or so until I can be in.

Had a similar problem some years back, that turned out to be a failed pressure relief valve, this is normally only to release pressure if the boiler over pressures, the water will or should vent outside.

[gsgsgs]

It sounds like the expansion vessel has been replaced, I called it a reservoir I guess the could be a leak but as far as I can tell there ar no damp patches.


Below the flue there is a small copper pipe with what looks like an elbow bend on it, when the boiler is running this more or less constantly drips.


Thank you for your comments.

[gsgsgs]

Thank you for your comments, I'll look at the website suggested and have another look for leaks.

[gsgsgs]

Had a similar problem some years back, that turned out to be a failed pressure relief valve, this is normally only to release pressure if the boiler over pressures, the water will or should vent outside.

I do have a drip from a pipe that is below the flue, another possible answer.


Thank you

[Rigsby]

You’ve found the cause, you are losing water (therefore pressure) via the PRV.
What will have happened is, the Expansion Vessel will have failed (now replaced) which has allowed a build up of pressure in the system, the PRV has done its job and opened to release the excess pressure.
Often when theses valves have been opened they get dirt on the seal seat hence they slowly pass water.
Sometimes you can “flush” the dirt away by manually opening the valve then repressurising the system.
It’s a common occurrence and the firm that replaced the EV should have checked / replaced the PRV at the same time.