Vaillant boiler incorrectly showing no pressure

[johnnycarmello]

My boiler is starting to randomly drop to zero pressure and turn off. When I go down to the cellar and open the filling loop, it instantly jumps back up to 1.5

Anyone ever seen this before?

 

[Last Plumber]

It sounds like an easy fix. You need a Gas Safe Engineer to it.
If you haven't had it serviced you might find the repair gets sorted within that plus cost of part.
Make sure you tell them it has a fault and describe the fault as you have done here, otherwise it could cost more than it should.

 

[johnnycarmello]

Had it serviced two weeks ago! I've text my engineer anyway. Hopefully he can fit me in and fix it before I head away for a couple of weeks.

It's funny, we lived in an apartment is a 15+ year old boiler from a company the engineers had never heard of. Always worried about it packing in.

Moved here where there's a relatively new Vaillant, and every week there seems to be a new issue with it!

 

[Deleted member 120897]

Had it serviced two weeks ago!

Was it definitely a service, or safety check?

Moved here where there's a relatively new Vaillant, and every week there seems to be a new issue with it!

Quite often it’s the condition of the system, not the boiler.

 

[johnnycarmello]

Yeah it was a service. Just off the phone with him - he's confused too! The whole system is around 2015, and was serviced every year. I have copies of all the certs.
Hopefully he can get to the bottom of it anyway.

 

[John.g]

When you repressurise to 1.5 bar watch the pressure as the system heats up and see if it approaches/reaches 3.0 bar, if it does then more than likely that the expansion vessel needs attention or renewal, you might also see water flowing from the relief valve somewhere outside the house.

 

[ShaunCorbs]

Is it the digi guage or a mechanical one ?