central heating system losing pressure on new install

[spada01]

Replaced the existing central heating system myself using SPeedfit. Put 1.5bar of pressure on Thursday to test and it's dropped to 1.25 bar. The system's been off.

I can't find any leaks at the joints and am wondering if this pressure drop may be due to the plastic expanding slightly under pressure? All rads have been bled so no air in the system I know of.

Is it normal for a plastic system to drop a bit of pressure when newly installed?

Before I get asked, yes I have used barrier pipe

 

[Boilerman2]

Could be release of air around the system, I would have thought that the pressure would have dropped to zero if there was a leak

 

[Dan Robinson]

Because of course when you pressure tested it to 10 bar like it says in the manual any leaks would have shown up.

 

[spada01]

Thanks - that's what I thought re a leak should drop pressure quicker. I found it in the end, a tiny leak from a joint not nipped up enough. It's one of the few compressions I have to allow plastic to chrome. It leaked very little but is all sorted an water tight now. First time I used plastic so I suspected it may have expanded slightly.

Dan. Not sure what manual you're referring to - it wont be any boiler's one as 10 bar would blow a boiler and is well above mains pressure. I've even seen rads that wont go that high.

 

[Kev F]

Speed fit should be tested to 10bar for 10 mins then dropped down to 2 bar for a further 10 min test