falling pressure on hot in shower

[Johntynycoed]

My shower uses a Bristan bar mixer and a salamander right pump. After experiencing falling pressure along with falling temperature. I have turned the pump round, not a handed pump, with no change. I then connected a couple of hoses to the pump and found that for the same volume of water the cold only takes 2/3s of the time that the hot does. This happens either with or without the pump running and no matter which way round the pump has been connected.. There is one pipe from the header to the cylinder and another from the header for the shower etc. I can't see anything wrong with the plumbing although I am not an expert.

A Salamander S type hot flange has been used to make the connection to the cylinder.

This problem does not seem to be caused by other taps being open. I have done an open end test as suggested by Salamander and that does not indicate a problem with what they call recovery, i.e. the tank not filling quick enough

Can anybody suggest what I might try next?

 

[Puddle]

Are you saying you are mostly getting cold water through shower,even when turned on hottest setting,if so it will be the shower valve cartridge faulty,the drop in presure is because hot not coming through
if not above please explain problem further

 

[Johntynycoed]

Thanks Puddle,

Yes it is something like that, but I wanted to clarify whether the imbalance in pressure of hot and cold could be the problem.

I've got a replacement cartridge and temperature stop from Bristan under the guarantee but I'm not sure whether this is the cause. I can call out a Bristan engineer under the guarantee but if it's not the mixer valve it will cost me £80.

I suppose if I fit the parts supplied I might be negating the guarantee, something I definitely don't want to do. So I have a slight dilemma.

 

[Puddle]

well you pays your money ,you take your chance,I can not advise you to invalidant cover,but if I had part,would fit it
also would mention there is a filter on hot and cold inlet,so check hot filter not blocked
These filters are located in the nuts at rear connecting inlets to shower bar

 

[Johntynycoed]

Thanks for tha advice, I'll check the filters too.