Ariston Combi Won't Re-Pressurise

[colindj69]

Hi all - After a drain down (due to having new rads etc), my combi boiler will not re-pressurise again. Water is filling the system back up but not enough to move the pressure gauge. I have changed the one way valve on the filling loop, and checked main water pressure, which is fine. It re-filled fine yesterday but now won't.
A bit of history, the house had all new rads fitted 6 months ago, was tested, then drained down about a day or 2 later, and was left like this until yesterday. I went to fill the system up and it was fine, spotted a leak on a rad valve so drained down, fixed leak, now I've got the above problem...
No leaks anywhere and pressure release valve is fine.

Any ideas

Colin

 

[easyflow]

Have you closed the heating valves on the boiler, if they are closed it wont pressurise.

 

[colindj69]

they haven't been touched at all. It pressurised fine yesterday, I even had the heating and boiler fully working. It was only because I spotted a leak on the rad valve that I drained it again...

 

[colindj69]

Sorted it... Turned out to be a faulty pressure gauge, or more precise, a slightly blocked tube leading to the pressure gauge...

I borrowed an external pressure gauge from a friend and seeing as there is a rad off in the spare room whilst it's being decorated, I connected the gauge directly to that, filled up the system, boiler gauge reading zero but my friends gauge reading 2 bar...
I then disconnected the boiler gauge from the back of the boiler pump and thats when I saw something clogging the small hole/tube leading to the gauge itself. Cleaned it out with a pin and it all works now...

Now I know what you are thinking, if that small tube is blocked, then it the whole system is probably bad.. True, although every rad and pipe work is new, boiler is 10 years old tho so I'm guessing its just the boiler that needs a good flush/clean..

Is there any kind of cleaner I can add to the system and run it for a couple of weeks then drain it ??

 

[easyflow]

Sentinol 400, leave in system for a few weeks flush through then add a good inhibitor like fernox.

 

[colindj69]

Many thanks. Already got the fernox, but will try the sentinol for a few weeks. The other rads will be ready to go on by then so I'll give it a good flush through with clean water, also can check for leaks one last time before I drain and add fernox for final re-fill...