Hey, would be very grateful for some urgent help with my boiler. About a fortnight ago the boiler stopped working; there was an error code that I do not recall. The water pressure had dropped into the red zone (just below 1). There was no obvious leak. So I repressurised it to about 1.5, reset it and the boiler started working. Everything was fine. But yesterday it stopped again. No drop in water pressure this time; the error code is EA. Tried resetting, it restarted and the hot water returned. Couple of minutes later it stalled again. Rang Worcester Bosch (boiler still in warranty), they said that the condensation pipe may have frozen. Checked the pipe - there indeed was some ice at the end, defrosted it by pouring hot water. Restarted the boiler and it seemed to work. We had to go somewhere and only came back today. The same error code, EA, is flashing again. No ice on the condensation pipe today. Boiler now makes a lot of gurgling noise on resetting. Initially the flame came on but now even that has stopped. Seems like there is air in the boiler. Checked an upstairs radiator but there is no air in that. Point is, why is there air in the boiler but no air in the upstairs radiator? How do I let the air out? How do I prevent it from reccuring? I tried looking for the "drain valve" but can't identify any. There is a metal pipe that goes outside (and is open ended) but there is no regulating valve on it. The picture of the underside of the boiler is here
. Any help will be appreciated.