Impeller Shower Pump - Thermostatic Mixer Cold

3

33064xeHG

Hi

Bit of a lengthy post one this, so my upfront gratitude for anyone who perserveres with it !


My ensuite shower had very week pressure - cold was just about strong enough to reach the fixed head, hot was non existent. H&C pressure to the bath was adequate, but as I wanted to install a tap-mixer shower here, I decided to have the upstairs pressurised with a pump.

So I’ve just had a Salamander ESP 75 twin impeller pump fitted to pressurise all hot & cold outlets upstairs. I’ve also fitted the mixer shower to the bath, which works fine.

However, the ensuite shower, (thermostatic mixer), although it now has good pressure, it’s output is consistently cold. I’ve checked its hot supply and it appears to be fine, i.e., isolating its cold supply outputs hot water at good pressure, albeit way too hot for a shower.

The only I can get an acceptable shower is to simultaneously run the cold tap on the bath. The ensuite works fine in this situation, the thermostatic mixer is a joy and responds to the temperature knob as needed. Ecstasy – it’s just a shame I don’t want to have to run the cold bath tap every time I shower :rolleyes:

My conclusion is that the cold supply to the mixer is at much greater pressure than the hot. I’m perplexed why as it is fed from the tank, not from the mains as appears to be a frequent issue from examples I’ve researched.

I’ve examined the hot & cold pipe work from the pump to the shower and can’t see anything particularly different - same pipe diameters, similar length, turns etc.

My questions are thus:-

1. should an impeller pump output equal pressure on hot & cold, in which case is my shiny new pump not working properly ? Or does it simply boost input pressures proportionally, i.e., if input hot is lower than input cold, then output hot will also be lower than output cold ?

2. Is pressure reducing valve immediately before the cold input to the ensuite mixer r the way to resolve this ?

Cheers
Gareth.
 
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both pressures should be equal if hot / cold is fed from the same cws.
so no need for a pev
 
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Have you tried re-commisioning the valve now that it operates with higher pressures? Some valves also have adjustments in the cartridge dependent on inlet pressure,
 
3

33064xeHG

gasguru

by 'commissioning' do you mean the temperature calibration procedure through which you set the mixed temp to ~38c ?

This is the only procedure mentioned in the manufacturers instruction (which to be honest are pretty cr*p).

thanks
Gareth
 
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Commissioning as per the manufacturers instructions...does the valve max/min inlet pressure comply with the insructions?
 

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