Hi there
I have an oil fired boiler and it has one pumped feed for the radiators and a gravity fed system for the hot water. I drained the system down and refilled it radiators work fine but no hot water. I have tried releasing the pipes on the Hot tank heat exchanger to release any trapped air but to no avail I am assuming I have some form of airlock but how do I get rid of it there are no bleed valves near the hot water tank.?

You might have to lift the safety valve lever to get the air out of the tank.