I’ve just put two radiators in my conservatory but lost all the water in the system due to a bad seal in a speedfix elbow. I sorted this but now I can not get my heating on to test it. I have bled all the radiators untill the air stops but there is no water getting into the pipes and theres a funny noise coming from the pump (I suspect it may be pumping air into the system). If its left on long enough it gets quite hot and starts making loud clicking noises. The valves are open but the pipe coming from it is still cold.
By “heat pump” I assume you mean a hot water circulation pump in a zoned hot water heating system. Such pumps use centrifugal impellers to pump water through the system. They should not need to be “primed” but the system must be full of water for them to work.
Make sure that the system is indeed full of water and any air has been bled from it. Make sure that the thermostatically controlled zone valve is open. If the system is full of water and the pump operates as you describe, then you either have a stuck zone valve or there is something wrong at the pump, such as a worn, broken, or disconnected impeller.
In multizone hot water systems there are two basic setups: 1) a single circulation pump feeding a manifold that distributes hot water through two or more zone valves; and, 2) a system where there is a separate pump for each zone, with the thermostats activating the pumps when heat is demanded. I’ve installed both systems. The first is cheaper and easier to install. I prefer the second as being more reliable and durable in the long run.