Pump doesn’t kick in unless running cold water only

[Sarahlg800]

we have a Salamander ct75 pump fitted (18 months ago) the pressure in the old shower was never great but since having a new on fitted we’ve had loads of problems. We were having to lower the shower head into the bath to initiate the pump or sometimes it would take 2-3 mins to kick in. Since yesterday though it kicks in when the shower is turned to cold but as you turn up the temp the pressure drops to the point of a trickle when it’s hot.

So annoyed as we’ve spent so much £ trying to get this right and just nit sure what to do next. New pump? Replace entire system eg get a combi boiler?? Literally clueless as you can tell so any help gratefully received

 

[Madrab]

It'll be the new shower, if it worked fine before.

The key with a fed system is to maximise flow where possible. If it was working ok before then the old shower must have allowed the min flow through each side of the pump for it to activate and stay running. The new shower obviously isn't, whether it has narrower waterways, narrower hose or restrictive shower head.

I'd have a look at the pump 1st though & make sure the filters etc are all clean.

 

[cross thread]

how much head of water do you have (difference in height from cold water tank to shower head)

 

[Sarahlg800]

The tank is in the loft so maybe 1m in height.