My daughter has a Glowworm Swiftflow 75 combination boiler
which keeps losing its cold fill pressure . It is initially set to 0.7 bar as specified but drops to approx. 0.2 bar over a period of time, resulting in the loss of hot water. I have checked for any
obvious leaks to no avail. Any suggestions to cure the problem would be appreciated.

Bob Norman, June 2007

go to merchants get FERNOX LS1 (or similar)
THIS IS A LEAK SEALING CHEMICAL.

getting this in the system is not easy without a pump -but you may disconnect a radiator to put it in. It won't be easy.

the fact you can not see a leak does not tell you everthing. It is possible and indeed probable that you could be pulling air into the system -ye sounds silly

I assure you I have 30 years experience in the field and 15 in the lab -- it happens - ait entrainment - more than likely near the boiler itself.
LS 1 does usually work - follow instructions carefully

dave broadbent, June 2007