Shower pump not working properly

[beinerts]

Hi all,
I’ve just installed a Salamander ESP 50 CPV twin pump to go to a new shower (and nothing else). The pump is configured as negative head and is fed from the cold water tank and hot water cylinder respectively. I’ve fitted an auxiliary CW tank to make sure I have enough hot and cold water.
Now, I’ve connected the pump as suggested, filled it before connecting the discharge pipework etc. I’ve also made sure that the pipes don’t drop down at any stage (to avoid air in the pipes) and flushed all the pipework. When I actually switch the pump on and test the shower (with a mixer valve) the cold water works perfectly and the hot water doesn’t! The hot water starts running very weakly and then dies out altogether, at which point my pump starts making unhappy noises and I run to turn it off. It’s really confusing me as the hot and cold water pressure feeding into the pump should be identical (the cold water tank also feeds the hot water cylinder).

Any help is greatly appreciated!

 

[beinerts]

Well, I found the cause for this by just checking everything over again. After disconnecting and testing it, the hot water inlet pipe was spluttering. I had obviously not given it a good run through before connecting. I did so before reconnecting everything (running water in - and out through - the pump etc.) and it's working fine now.