Powermax 155x pressure problem

[briar]

Help! I am going MAD!
I moved into a brand new flat with a brand new powermax 155x boiler in the summer and ever since have been having a nightmare!
I have had about 8 different engineers in who between them have probably changed as many parts! Nobody seems to have a clue what is going on!
Basically my boiler has a pressure valve on the front which keeps gradually dropping to the point where the boiler goes into lockout and fails! To make the thing work again we have to top it up using a tap inside!
Some people have told me that it is notmal to have to do this every few weeks! (I find that hard to believe!) others have told me it should only be done about once a year if at all!
Firstly which is right?
Secondly if I am correct in thinking I have a problem - what is it?
We have had the expansion vessel replaced and I think the pressure release valve too!
At christmas a guy spent 4 hours sorting it only for the pressure to be gradually dropping again!
There are no signs of any leaks!
HELP!!!

 

[weareleeds]

Check radiator valves when system cold (look under plastic caps @ spindle & feel for dampness) also put finger inside plastic cap. It is quite common for builders to skimp on quality rad valves which can't cope with pressure generated (1 bar plus)

 

[Bryan King]

There are many possible reasons for pressure loss.
i list some below


1) leak on heating circuit

2) Faulty Pressure relief valve

3) Faulty expansion vessel Nitrogen/air loss or split bladder

4) Excesssive air in system

5) Expansion vessel to small ( noticeable by pressure valve running when temp is high.

 

[briar]

Thank you to the people that have replied so far - I will check those pesky radiators thoroughly and suggest the other stuff to the next engineer who I get in however to be honest I think most of those things have been covered!
One guy I spoke to did say something about pipes on the outside of my property that appear to be going nowhere (do not know technical name for these!) may be leaking. As I live in an apt it is hard to see which are my pipes but I think I have located these and every now and then I do see a stream of water flow out - about 5 seconds worth! Could this be anything to do with it?