A single boost SP2B (£125) will stop an 8.5 KW electric shower dropping out because of low pressure, and it will protect the shower against pressure fluctuations in over 95% of cases.

The easy answer as to which SPB you need is that a SP2B should sort any pressure problem, but in this blog I will use the question from a potential customer, Mr W.A, to answer in detail and explain how the SPB works to solve problems with electric showers.

I was contacted by this potential customer, who wanted to improve his 8.5 KW T80i Triton Shower.
We are often contacted by people who have existing problems looking for solutions, and although I love talking to my customers, I thought, because this problem is fairly common, to explain in detail why ShowerPowerBooster works.

This is the question emailed to me today:

I am using an electric shower with mains water input.
Static pressure is 1.4-1.6 bar (but can drop to 0.9bar).
Normal max output (i.e. with temperature at min.) is approx. 6L/min
I would like an improvement of about 15-20% in the flow and improved resilience to input pressure fluctuations.
Your graph doesn’t show what effect increasing the input pressure has.
(It is a standard Triton T80i shower and it is running with the low pressure cut-out on the verge of tripping. The pump would be plumbed to supply the shower only.)

W.A – 11.35 am 27.4.2022

How much hot water can a 8.5 KW Triton T80 electric shower produce?
The amount of hot water that an electric shower can produce is limited by the heating element within the electric shower, and only by buying a bigger electric shower will you increase the output. The maximum water volume that can be heated to 40 degrees C using the T80 shower is taken from Which Magazine’s independent trials. Which Magazine wrote a report in 2021 for the Triton T80 and in its “Expert Opinion” they wrote ‘On the high setting, water flows at a rate of 3.6 litre per minute, which is low compared with the average for models we’ve tested in 2021.’ Which & Triton both praise the shower for saving water, but I would be unhappy standing under a shower giving 3.6 litres a minute as it would take a long time to wash out the suds. You are under the shower for longer soI see no water saving at all.

For efficient showering you need a quantity of water to wash away suds. My personal thought is that you need 30 litres per shower to remove suds, and Which suggests 35 litres. If you need 35 litres then you will stay under the shower giving 3.6 litres a minute for 10 minutes to achieve this.

Shower Dropping Out
Mr W.A mentioned that the shower “dropped out.” Which commented on the Triton T80 saying ‘When you’re showering and someone flushes a toilet or turns on a tap somewhere in the house it’s fairly common for the water pressure to drop and shower temperature to briefly rise.’ If all you want is your Triton T80 shower not to drop out or fluctuate, then a ShowerPowerBooster will protect and boost that shower at all times. If it’s operating at 40 degrees centigrade and you have a flow of 3.6 litres a minute at 40 degrees C, then a SP2B will give an additional 0.4 bars, and the SP2B (£125) is all you need. If it drops out at 6 litres a minute, then a SP21S double boost (£155) giving 0.2 + 0.2 = 0.4 bars is what you need.

Alan Wright
BSc(Hons) C.Eng. M.I.C.E
25 years working for Water Companies, Petro Chem Industry, House Building & Renovation
Inventor of the ShowerPowerBooster (and much more)

27/4/2022