Low hot water pressure in shower

[Mike McCue]

Help! When I move the shower lever to hot position the flow drops significantly. I have successfully changed the shower pump and then the single lever concealed valve (Access via airing cupboard) with no change whatsoever. Obviously not a plumber, what am I missing? any help would be gratefully appreciated.

 

[Aire]

Filters on shower inlet or stuck non return valve perhaps? What shower is it?
Also when you changed the pump, did you check you actually had a hot flow to the pump?

 

[Burger]

Help! When I move the shower lever to hot position the flow drops significantly. I have successfully changed the shower pump and then the single lever concealed valve (Access via airing cupboard) with no change whatsoever. Obviously not a plumber, what am I missing? any help would be gratefully appreciated.

Gravity fed ? Could have a snapped gate valve, try running another hot water outlet, eg a tap.

 

[Harvest Fields]

If the hot water is ok everywhere else. It should be either a blocked filter in the shower or a blocked NRV.

 

[SlimD]

Definitely check the filters. Could be debris in them or scale build up. Also check the isolation valves on the hot side are all fully open (including any valves on the hot feed to the pump) and that they've not been partially closed restricting the flow.