Pressure loss central heating system

n.hussain03

I have property that I first got the keys to last august. It was being renovated and finished earlier this year. I was due to move in last month but with all the corona stuff, that has been put on hold. Anyway I do pop in to check if everything is ok.
There was no hot water when I visited today and when I checked the boiler(Ideal Logic 30) it was showing an F1 error code. This basically means low pressure in the central heating system, the gauge confirmed this, The boiler had shutdown due to this. I had a wonder around, felt each of the valves on the radiators and I could not feel any leaks and no signs of marks on the ceilings. 
The property is empty however over the winter the heating was on twice a day for a couple of hours to warm up the house and prevent frozen pipes and damp. The system was filled fully around the 2nd week of Jan and inhibitor added as well. My understanding is that during normal operation there will be loss of pressure eventually but how much is too quick? 
I have filled it to 1 bar for now which may be a little low but will monitor to see if the system is loosing pressure. 

lesalanos

If it's a tiny leak you may never find it as it may evaporate if leaking onto a pipe.  3 months in my opinion isn't a great cause for concern.  Filling to 1 bar may have only taken a pint 

n.hussain03

I checked again this weekend and from 1 bar it has lost 0.25 bar over 7 days, I have a suspicion it is one of the radiator valves on the ground floor. The rate does suggest it is a small leak. Once lockdown is over I will get it swapped out.