We have a Worcester Greenstar 27 HE system boiler which was installed in combination with a Megaflow unvented cylinder about 2 years ago when our extension was built.
The system has worked well but I noticed last week that the pressure gauge was reading zero bar. I repressurised the system and checked for leaks (none found). Since then I have been in a cycle of having to repressurise from zero every couple of days.
The system is on contract with British Gas and they have been out a total of three times in the last week. Most recently (today) a new siphon was installed. Unfortunately this hasn't solved the pressure loss.
It seems most likely that a leak exists, but I have inspected all radiators, plus ceilings and under floors.
One observation that was made -though not necessarily related - is that the boiler seems to be plumbed in with two zone valves and no bypass circuit. I had noticed that the temperature in the boiler climbs to around 90 degrees whenever the heating shuts off. However, there's nothing in the installation instructions for the boiler about requiring a bypass circuit. Just wondering if there is a built-in automatic bypass on this model?
Any help or suggestions extremely welcome. Please go easy, this is not my field of expertise!