I've had a new gloworm gas boiler installed recently. The problem is that the pressure drops on it over about a 10 day period from 1.1bar to 0.4 bar. Each time it drops I turn the valve and let the pressure back up to around the 1bar. I have had the builder who installed it back and he said he had made and adjustment so that it 'mains filled' just before Christmas. I understood this would rectify the problem. However, when I returned from being away over Christmas the boiler had again dropped to 0.4 and cut itself off (as it's supposed to do when this happens, according to instructions). I'm just lucky there was no frost. I will get the builder back again but I would appreciate if someone could advise me on what I should be asking him to do, as I really don't understand the problem. Thanks!