Pressure loss within tolerance?

[cam123]

Hi, could anyone offer their advice on the following please -

I'm in the process of a full house renovation, and have just completed the first fix plumbing (or rather the plumber has) for c. 12 rads in new locations. Not all of the pipe work is new, but i'd say 70% is. It's all in copper and none of the rads are fitted yet.

Before boarding up, I wanted to pressure test it (it will eventually be running off a system boiler and megaflo cylinder) and so have a gauge on the top radiator flow pipe, but wanted to know how I should interpret the results!

We've basically been testing it at 3bar (with water, not air) and lost 0.2 bar over two days. I've now re-set it to 3 to see if it falls another 0.1 before tomorrow.

My plumber has checked over all of the pipes and can't find a leak, nor can I.

Could this be down to "settling" or the result of air trapped and moving about rather than a leak? And if I do have a leak, how much water would this drop in pressure actually equate to? We're puzzled that we can't find it!

Thank you to any able to offer their expertise and advice!

 

[Boilerman2]

Unless the temperature of the surroundings remains constant, it is not unusual to see a slight increase or decrease in pressure as water expands and contracts to temperature, if there was a significant problem the pressure would soon drop to Zero!

 

[cam123]

It was reset to 3bar yesterday afternoon and it has dropped again overnight when I just checked it now. If temperature makes quite a difference, how much of a difference? What is acceptable tolerance and what is a leak?!

I can get the heating engineer back to get him to sort it out or I can get the plumber to re-check everything (again) or i can assume that there isn't a leak.... either way, i need to decide quick because I have carpenters and plasterers backing up behind the plumbing!