Pressure too High on my Potterton Lynx2 Combi Boiler

A little Help / information please ?

Ok, I have a Potterton Lynx2 Boiler, Judging by what i've seen on the many helpful posts on this forum this Boiler is Dreaded by some and Feared by others!..

My problem is that when i switch on the central heating the pressure Guage just keeps rising from its initial 1.5 bar postition to all the way round to the top/off the dial (thats when i switch it off)when i use the Hot water the dial remains static (no problems there..i think) the problem started a few weeks ago when it started to get cold,i switched on the central heating for the first time since the previous winter, prior to that i had bled the radiators in the house (in the correct maner i.e. furthest away from the boiler 1st) as they had been off/standing all summer too.

When i first fired it up it would just not work at all the ignition was all messed up and it would keep cutting out, after some research on these forums it seemed that there was a problem with the PCB board,.... i got a new one...now that all works fine! everything fires up and starts first time...no problems there! then the the pressure gauge was really low so i topped up the system via the top up switch, all good there standing pressure 1.5 bar! now when i turn it on the pressure just climbs (as decribed above)

Can anyone explain if there is anything i can do to fix this? or what the cause is? the thing is that i am really really skint/broke at the moment so i would like to be in the situation of being able to tell the engineer what the most likely problems are so he can get onto it with the least amount of fuss and cost to me.

Many thanks in advance.

Rich.

Seems that you have a deflated expansion vessel or blocked pipe/flex to the vessel. Easy to drain system with a drain valve open and check expansion vessel charge with tyre gauge or foot pump, follow manuf for exact charge pressure.

Thanks for the quick reply...
you say this is easy....is this something i could do myself or should i bite the bullet and get an expert?...
i cant see where to drain the system, what am i looking for? there is a blue doorbell shaped object with what looks like a bike valve on it...thats for charging the system, right?

You need to release blr pressure to zero with a drain valve open and check vessel charge, the expansion vessel is a pain to get to on the lynx, you may have a seperate vessel fitted? It is worth having it looked at if you are unsure.

yes i have the pain to get to expansion vessel on mine (typical)
well looks like i'm gonna have to call someone out one this then, unless anyone else has any ideas...


Thank you very much for your advise ..really appreciate it.