Rocket Giotto occasional no boiler pressure

[fg1972]

Hi all,
I've noticed on 2 occasions in the last couple of days after powering up the machine there is no boiler pressure at all as if the heating element is not working.
Pump still works and heated water (assuming it is heated via the HX) comes out of the group head but is not hot enough to make proper espresso.
After switching the machine off and on again, the heating element seems to do its job, heating the water in the boiler building pressure within a minute or so.

Before I go poking around inside the machine looking for a fault if I manage to reproduce the problem, does anyone have any suggestions on what to look out for?
I'm quite comfortable working with mains electricity by the way.

Cheers
F.

[burr]

If you let it warm up for 5 mins and open the steam valve, do you get a quick burst of air/steam and sudden loss of pressure, folllowed by normal operation? If so it might be the anti-vac valve.

[fg1972]

Hi burr,
When it played up, no steam at all, zero on the boiler pressure gauge even after 20 mins.

[burr]

Hmm well that is odd - no pressure would suggest no heat, although you have partially heated water coming out. I'm clueless!