shower getting colder

[NickJ]

Hi All,
I recently replaced the bathroom in my house and replaced the old bath with a bath/shower mixer tap. The pressure was very low (gravity fed system) so I removed the check valves that i had fitted previously but there was no improvement so I got a plumber to install a salamender pump.the pressure is now ok, but as the shower runs, it gradually gets colder and colder. There is more than enough hot water at all other outlets.It got worse in the last couple of weeks (possibly a build up of minerals from hard water). I had a cheap mixer tap and suspected it was the problem but I have now replaced it with a grohe tap and I still get the same problems. Could anyone help? Do I just need to get some check valves fitted? :confused5:
Thank you all in advance for your advice (please bear in mind that i am new and not a plumber so please dont be too harsh if I have done something wrong!)

 

[kris]

Hi there Nick and welcome to the forum, There could be a number of different causes for this, the mixer is flowing cold because its more over powering the hot or the filters in the pump need cleaning out,,, did you re instate your non returns when pump went in ? could be a drop of air on the hot side , this is the reason we use the different flanges at the hot water tank to eliminate air, the cold has a higher head of pressure everytime as the CW tank is always higher than the cylinder,

 

[Whyme]

Like kris asked. Where did he tap the hot from, did he use a special fitting in the cylinder also what pump did he put in (model etc).

 

[NickJ]

Thanks for your replies. The hot was taken from the top of the hot water tank using an s flange. The pump is a salamander rsp 50. I have already cleaned the filters and there wasnt much improvement. Before replacing the mixer, I removed it and checked the flow coming from both sides and the hot one seemed slightly better than the cold which is why thought that the mixer had to be faulty. I havent put the non return valves back as thenplumber said that I should get equal pressure with the new pump. I will have to put it back tomorrow..
Please let me know if it could be anything else, otherwise I will keep you updated tomorrow. Thanks again for your help

 

[kris]

This might be a silly one but when you fitted the bath was the cold water to the tap not mains water originally ? or was a pipe ran in from tank? its just not popular to have tank fed cold water to baths ? this would explain although shouldnt have that onto pump, Just a thought even if long shot ,,,,

 

[NickJ]

Deleted

 

[NickJ]

Hi Kris, the cold water was from the water tank in the attic and I did not alter the plumbing when replacing the bath. Thats why a twin pump was needed. After reading a bit more, it seems that a non return valve would not help as the pressure from the cold would block the valve and would therefore stop any hot water from reaching the mixer, is that correct? From what i read, it seems that i need to install a pressure equaliser valve, would that solve the problem?