Boiler pressure dropping

[fivegoldstars]

Evening all, looking for advice. Worcester Bosch 4000 boiler, exactly 2 years old. Serviced annually, just due it's 2nd.
Noticed lights flashing yesterday and pressure was .8. Usually check this fairly regularly but it's never strayed from 1.2. Topped up last night to 1.2 and it dropped to 1.1 in about 4 hours. Thought it might be settling, but today it's 1.0.
Have checked all rads and exposed pipework for leaks. Checked around route of pipes for damp patches but nothing obvious. Unfortunately 50% of pipes either under laminate or concrete so not easily inspected. However, would expect a leak to be pretty significant. Nothing seems to be coming from boiler expansion pipe - what is my best course of action at this point?

 

[jurassic sparkk]

Isolate boiler from flow and return and take it from there.

 

[Harry Bloomfield]

Isolate boiler from flow and return and take it from there.

Not very explicit - With heating system cold...

Try pressurising to a set level, then turn boiler off, isolate both flow and return, then finally keep an eye on the pressure.

If pressure still drops substantially, the boiler has a leak.

If not, try watching the pressure gauge, whilst opening the flow or return closed earlier. If pressure now drops suddenly, the leak is from your system/external to the boiler.

 

[fivegoldstars]

So, quick update. Topped up again to 1.2 last night with a view to isolating later today when everyone out for the day. Pressure stayed steady overnight, but dropped to 1.1 by 3pm today. Checked ziplock bag which is placed over expansion pipe and it has about 150ml of water in/bag steamed up.

 

[CBW]

So, quick update. Topped up again to 1.2 last night with a view to isolating later today when everyone out for the day. Pressure stayed steady overnight, but dropped to 1.1 by 3pm today. Checked ziplock bag which is placed over expansion pipe and it has about 150ml of water in/bag steamed up.

So you have a passing prv and or expansion issue.

 

[Elkato531]

So on the service make sure the expansion vessel is checked and the prv is replaced. Not sure about this model but hopefully Worcester have made the prv more accessible than on earlier models.

 

[fivegoldstars]

Contacted Boxt who the service plan is with and advised there may be a PRV issue to check on the service. They state that this would not be covered under a service, which seems odd because most services state 'inspect or replace' against items such as valves.
However, they did pass it on to Bosch who have arranged a warranty repair next week.

 

[Madrab]

It would be a warranty call if it's only 2 years old. That being said a proper service should check the EV for pre-charge but a lot don't.

Has the pressure gauge has been rising up to 3 bar when the system is running? Quite unusual though for a PRV/EV issue on a boiler that's only 2 yrs old, unless the system itself is really large? Are there lots of large rads?

 

[fivegoldstars]

No, not particularly. Standard 3 bed with a couple of large doubles then 5 regular singles over 2 floors. Because it's a digital pressure display which you need to activate, it's not as easy to keep track of any fluctuations. Since last top up to 1.3, it's now static for 3 days, although heating hasn't been on either.

 

[Madrab]

Because it's a digital pressure display

Don't see the point of digital displays, unless it's part of the default readout. With them and/or where an external loop is used, I always fit one with a manual gauge on it.