I have recently moved my hot water cylinder, 3 port valve, pump , cold water tank and heating expansion tank into my loft. Everything seems to work fine but when i turn on the hot water only the boiler fires for a few minutes then shuts off on the boiler stat, without any hot water going through the cylinder coil.
I do not understand why it does this because when when i turn on the heating and hot water, i get hot water going through the cylinder coil. The heating works fine both on its own and with the hot water turned on.
For some reason i seem to have poor circulation on the hot water side of my heating system, which causes the water not to circulate from the boiler and cuts it off. I just can't figure out what could be causing this.
I have checked the 3 port valve and pump and they seem to work fine. I have fitted air vents at my high points, so i dont think it is trapped air. I also back fed the system off the mains cold water to try and push out any air pockets and i still had the same problem.
Could it pssibly be that my pump is located in my loft (on the flow) and my boiler is downstairs in the kitchen? About 7 meters between them.
I will be grateful of any advise.
Ant.