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
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!