Boiler pressure

[Funkyboy]

Hi all,

Is it normal to have to top the boiler up 0.2 bar every 4mths?

Thanks

 

[Chuck]

A couple of questions first:

What pressure do you top it up to when the system is cold? What pressure does it rise to when the system has been heating for a while? How old is the boiler / pipework?

 

[Funkyboy]

A couple of questions first:

What pressure do you top it up to when the system is cold? What pressure does it rise to when the system has been heating for a while? How old is the boiler / pipework?

Boiler is a Worcester Bosch 4000 and is 19mths old. Pipe work is around 20 years. Pressure rises to 1.7 when heating is on. System is topped up to 1.3

 

[Chuck]

There probably is a water leak somewhere but it's going to be small and hence difficult to detect.

In your position, I'd have a careful look at all the radiators, particularly the valves and joints, for evidence of water escaping, e.g. rust, or white 'crusting'. Also check ceilings for staining and be alert for signs/smells of damp wood/plasterboard particularly around pipework and in ducts. If there is an air admittance valve (should be at the highest point in the system) have a careful look to see if it may be the culprit.

Keep a diary of when and how by how much you need to top up the system and try to do this in a consistent manner so you can monitor whether its getting worse and plan accordingly.

Mention the issue when the boiler is serviced and ask your engineer to check the boiler carefully for any evidence of a small leak that might explain the loss.

If checks, such as the ones above, don't find the leak many people will decide to live with a leak of this size. If it is getting worse, it will eventually make its presence obvious and be much easier (and hence cheaper) to find.

There are specialist leak-finding firms who use thermal cameras, ultrasonic detectors, tracer gas, tracer dye, etc. to find hidden leaks but a drop of 0.1 bar / month may be below what they can reliably find. If you don't like the 'watchful waiting' approach you could call one of these firms explain the problem and see whether they think they can help.

 

[Funkyboy]

There probably is a water leak somewhere but it's going to be small and hence difficult to detect.

In your position, I'd have a careful look at all the radiators, particularly the valves and joints, for evidence of water escaping, e.g. rust, or white 'crusting'. Also check ceilings for staining and be alert for signs/smells of damp wood/plasterboard particularly around pipework and in ducts. If there is an air admittance valve (should be at the highest point in the system) have a careful look to see if it may be the culprit.

Keep a diary of when and how by how much you need to top up the system and try to do this in a consistent manner so you can monitor whether its getting worse and plan accordingly.

Mention the issue when the boiler is serviced and ask your engineer to check the boiler carefully for any evidence of a small leak that might explain the loss.

If checks, such as the ones above, don't find the leak many people will decide to live with a leak of this size. If it is getting worse, it will eventually make its presence obvious and be much easier (and hence cheaper) to find.

There are specialist leak-finding firms who use thermal cameras, ultrasonic detectors, tracer gas, tracer dye, etc. to find hidden leaks but a drop of 0.1 bar / month may be below what they can reliably find. If you don't like the 'watchful waiting' approach you could call one of these firms explain the problem and see whether they think they can help.

Thank you for your thoughtful and very helpful reply. I have been keeping a log of pressure and dates and how long the boiler has been off for when a reading is taken. I will as you say keep an eye on it and see if it gets worse by needing more frequent topping up

 

[Best]

Boiler is a Worcester Bosch 4000 and is 19mths old. Pipe work is around 20 years. Pressure rises to 1.7 when heating is on. System is topped up to 1.3

I agree with checking radiator valves and any compression joints for signs of white or green staining/corrosion.
Some of the leaks are microscopic.
Check around the pins of the thermostatic radiator valves when you remove the heads for any sign of corrosion - often white in colour.
Also check motorised valves as they surprisingly can leak through the seals.
Any auto vents are culprits of leaking.
I guess the prv has been checked for passing?