The shower type has to match the water system. A mains-pressure mixer on a gravity-fed system will dribble; an electric shower on a good mains supply is a waste of a good supply. Measuring the flow rate first is what prevents the most common and most annoying mistake in plumbing.
Match the shower to the system
| Your hot water system | What suits it | Avoid |
|---|---|---|
| Gravity – loft tank and vented cylinder | Low-pressure mixer, or a pumped mixer | Anything specified for mains pressure |
| Combi boiler | Mixer valve rated for the boiler’s flow rate | High-flow rain heads and body jets, which the boiler cannot feed |
| Unvented cylinder | Almost anything, if the incoming main is good | Nothing much, provided flow was measured |
| Mains cold only, no useful hot | Electric shower | A mixer – there is nothing to mix |
| Marginal mains flow everywhere | Electric shower, or resolve the supply first | Anything with a high flow demand |
A shower needs both. Pressure is the force; flow is the volume arriving per minute. A gravity system usually has adequate flow and inadequate pressure, which is why a pump fixes it. A restricted mains supply has adequate pressure and inadequate flow, and a pump will not help. Measuring both takes ten minutes and it determines everything.
The types
Electric shower
Takes cold water only and heats it instantaneously with an electric element. Independent of the hot water system entirely, which makes it the right answer where hot water is poor or where a shower is needed in a location with no practical hot supply.
The trade-off is flow. The element’s power determines how much water can be raised to shower temperature per minute, and that is a hard physical limit. A higher-rated unit gives a better shower and needs a bigger cable and a suitable supply – an upgrade from a lower to a higher rating is frequently an electrical job as much as a plumbing one. In winter the incoming water is colder, so the same unit delivers less flow at the same temperature, which is why electric showers feel worse in January.
Mixer shower
Blends stored hot and cold. Simple, reliable, and capable of excellent performance if the system supports it. A thermostatic mixer holds temperature when another outlet is used elsewhere in the house – which is both a comfort feature and a genuine safety one, and it should be considered standard rather than an upgrade.
Pumped or power shower
A mixer with a pump, for gravity systems. It solves the low-pressure problem properly. The pump needs correct feeds – a dedicated draw-off from the cylinder rather than teeing into an existing pipe – adequate tank capacity, and a sensible position for noise. It also needs to be the right type: negative head where the pump sits above the tank’s water level, positive head where it does not. Getting that wrong means a pump that will not prime.
Digital shower
Electronic control with a remote processor, giving precise temperature and often remote start. Genuinely nice to use. More expensive, more to go wrong, and the processor needs to be somewhere accessible – which is a decision that has to be made before anything is boarded over.
Installation details that determine whether you like it
- Valve height and position. Being able to reach the controls without standing under a cold spray is a small thing that matters every single day.
- A riser rail as well as, or instead of, a fixed head. Adjustability suits more people and is essential if anyone may shower seated.
- Pipe sizing. A shower fed by an undersized or long-winded pipe run will underperform regardless of the valve.
- Isolation valves on both feeds, accessible. Without them, servicing the valve means draining down.
- The right screen or enclosure, properly sealed, with the tiling set out around it rather than the other way around.
- Extraction. A shower puts a lot of moisture into a room. See bathroom ventilation.
- Scale protection in hard water. Shower heads and thermostatic cartridges scale up steadily here, which is one of the more visible everyday benefits of softening.
When a shower disappoints
- Poor flow from the start. Nearly always a system mismatch – the shower is specified for more pressure or flow than the system delivers.
- Flow that has declined over years. Scale, in the head, the hose or the valve cartridge. Descale the head first; it is free.
- Temperature swinging when a tap is used elsewhere. A non-thermostatic valve, or a system where the shower shares a feed with other outlets.
- Running hot then cold on a combi. Usually the boiler struggling to modulate down to the shower’s flow rate, or a scaled plate heat exchanger.
- Cold in winter, fine in summer, on an electric shower. Normal physics rather than a fault – the incoming water is colder so the same power heats less water.
- Pump that will not start, or hunts on and off. Usually a feed or head-type problem rather than a faulty pump.
Weak shower? Descale the head first. If that does not fix it, the answer is in the system rather than the shower.
Questions we get asked about this
Why is my shower so weak?
Most often the shower is specified for a different water system from the one you have. Second most often it is scale – in the head, the hose, or the valve cartridge. Descaling the head is free and worth doing before anything else.
Will a pump fix it?
If you have a gravity system with a loft tank, yes, and it will transform it. If you are on a combi or an unvented cylinder, no – and pumping directly off the mains is not permitted under the water fittings regulations.
Is an electric shower cheaper to run?
Per shower, generally not – electricity costs more per unit of heat than gas or oil. Where it wins is that it heats only what you use, with no stored water losing heat all day. It also keeps working when the boiler does not, which is why many houses keep one as a backup.
Can I have a rain head?
Only if the system can feed it. A large rain head needs substantial flow, and on a combi or a marginal mains supply it will disappoint. On an unvented cylinder with a good incoming main it is excellent. Measure first.
What is a thermostatic shower and do I need one?
It holds the outlet temperature steady when pressure changes elsewhere in the house – so a tap being run does not scald you. It also has a maximum temperature limit. It is both a comfort and a safety feature, and we would treat it as standard.
Can you fit a shower where there is no bathroom?
Often – it needs a water supply, a drainage route with adequate fall, and for an electric shower a suitable electrical supply. Where gravity drainage is not available, a pumped waste is possible. It is a survey question.
What happens when you call
Call and describe it
You speak to an engineer, not a call centre. Most jobs can be narrowed down on the phone.
We look at it properly
A real diagnosis before a price, and a straight answer if it is not worth doing.
A written quote
Itemised, so you can see what you are paying for.
The job, and the paperwork
Certificates where the work needs them, and what will need attention next.
Where we do this work
Across Norwich and the whole of Norfolk. If you are on the edge of the county, call and ask — we will tell you honestly whether we are the right people.
- Norwich
- Wymondham
- Dereham
- Attleborough
- Aylsham
- North Walsham
- Cromer
- Diss
- Loddon
- Long Stratton
- Watton
- King's Lynn
Need this doing?
Call and describe the problem — you will speak to an engineer, not a call centre. Written quotes, no estimates over the phone.