new electric shower not working

Gainsborough are really sensitive to water pressure, and are generally pretty cr ap.

Tritom, Mira are a but more forgeving to water pressure.

 

I had the very same problem,plenty of pressure but wouldnt work,I too changed to another of the same make 'gainsboro'I put a restriction in the shower head which caused a slight back pressuse, therefore making the pressure switch, its been no problem fo 2 years now.

 

Help! Am on shower number three. Newly installed by
plumber Gainsborough 9.5. First - dial didn't turn.
Spent ages on phone with Gains engineer. Returned to
B&Q. Shower two, would not run hot. Shower three.
Will not run hot (not even slightly warm). Gains
engineer comes out. Electrics fine. Reason will not
run even slightly warm is "water pressure too low".
Not actually said what it is. Blames plumber, but no
real reason given. However, did agree that taps have
plenty of pressure. To me, the cold water from the
shower head is much better than at my last house and
many others I know.
Q1 - could this really be the cause of plenty of flow
but NO hot water at all?
Q2 How do you actually measure pressure?
Q3 How would you know (as a layperson) before you buy
a particular shower that it MUST have a certain
pressure? (Not on mains, but - as said - very
powerful in all taps)
Q4 what can I do? Spent £400 so far . . .

You need to know to running pressure AND the flow rate of the actual supply to the shower and make sure the shower you buy is suitable... The best way to find out this info is to get a plumber to test it for you as the test equipment can be expensive if you are only using it once.

Triton are much more tolorant than Gainsborough and different models have differing requirements.

You need pressure to activate a pressure switch to switch the heaters on. Too much flow and the water passes over the heaters too quickly to heat up and you get a luke warm shower, too little and it gets too hot (and a dribbly shower).

If it's not on the mains then you could put a pump in to boost the pressure.

So to answer you Q's

A1 Yes - you can have loads of flow at very low pressure
A2 With a pressure gauge
A3 Read the back of the box / download the instructions / ask a plumber
A4 Return the shower (if you can) and get a pumped electric shower e.g. Triton T80si / T90si (if you are NOT on mains water) or add a pump to boost the pressure (YOU ARE NOT ALLOWED TO PUMP MAINS WATER) it must be feed from a storage cistern. But you will still need to know the pressure and flow to make sure whatever shower you choose is suitable.

Hope this helps
CWP

 

Most showers need 1 bar 'back' pressure - caused by the holes in shower head (hence never run shower without a head). Try a head with smaller holes?

I remember Tony@agile giving a useful rule of thumb for pressure measurement. Something to do with how hard you have to put your finger over the tap to stop the flow.

 

A wek to fit an electric shower!! Jeez Im in and out in about 3 hours.