possible airlock

bordercars

friend has an oil fired sysyem, ran out of oil. got oil but couldnt get boiler to light. plumber called fired up and checked rads coming on, as emersion had been used for DHW couldnt check. all was working fine, turned emersion off boiler fires up but no hot water, just runs cold. as an MSE'r want to help before calling plumber back. is this an airlock and cured by hose from hot to cold tap and pushing air out of vent. if so am i right in saying, join with hose, turn on cold, open hot , when closing do i do cold first then hot or vice versa. or am i wrong and he need plumber. what else can be checked.

thanks ever so

ormus

it can also be a stuck 2/3 port valve.

keystone

Unlikley to be an airlock as system wasn't drained. As Ormus suggests check the 2 or three port valve. Take the head off (some a screwed on others just clip on and see if the valve turns freely by hand. Now try the DHW again this time look at the base of the head and see if it operates. Does the pipework get hot? What is the setting for the cylinder stat? Did plumber check any of these? "Can't check DHW because immersion has been on" seems a bit lame to me.

Cheers