Shower Installation
Hertfordshire, Bedfordshire & Cambridgeshire
Shower installation across Hertfordshire, Bedfordshire and Cambridgeshire. Electric, mixer, thermostatic and digital, specified against what your water system will actually deliver rather than what the box claims. Call 01462 506 374 or request a survey.
Start with the water, not the shower
Almost every disappointing shower in this county was chosen before anybody measured the supply. The type you can have is decided by what feeds it.
Combi boiler. Hot water comes straight off the mains, on demand. A thermostatic mixer is the natural fit. The limit is the boiler’s flow rate at your incoming pressure, and it is a hard limit. You cannot fit a pump to a combi. Vaillant states it plainly: a combi must take water directly from the mains, so a boiler pump to raise pressure is not possible. If a combi shower is weak, the answer is an electric shower, a different boiler type, or accepting it. Anyone offering to pump a combi is either misunderstanding or misleading you.
Unvented cylinder. Mains pressure hot and cold, usually the best showers in domestic property. No pump needed and none wanted.
Gravity fed, meaning a cold tank in the loft and a cylinder in the airing cupboard. Pressure depends on the height of the tank above the shower head. This is the one case where a pump is genuinely the right answer, and it is pumped from stored water rather than off the mains.
The pump rule most installers get wrong
Worth knowing before somebody quotes you a mains booster.
A pump or booster drawing more than 12 litres per minute, connected directly or indirectly to a supply pipe, is notifiable to your water company under the Water Supply (Water Fittings) Regulations. You must give notice and you must not begin the work without consent, which cannot be unreasonably withheld.
And here is the detail almost nobody mentions: the approved contractor exemption does not apply to pumps. It covers only three specific items on that list and a booster is not one of them. So an installer telling you their approved status means no notification is needed is simply wrong.
Above 12 litres a minute, the compliant route is not direct mains boosting at all. It is a break tank or accumulator with the pump drawing from stored water.
One more, on the pump itself: a single positive head pump is not suitable for mixer showers and taps because of the potential imbalance within the mixer. Twin pumps handle hot and cold separately. Where mains pressure can push back against the pump, you need a negative head or universal pump with a pressure vessel.
Electric showers, and the numbers that decide it
An electric shower heats cold mains water as it passes through, so it works regardless of your hot water system. That makes it the answer in a lot of awkward situations. What it needs is pressure and flow at the inlet, and a proper electrical supply.
Triton’s published minimums give you the shape of it:
| 7kW to 8.5kW | 1 bar running pressure at 8 litres per minute |
| 9kW and 9.5kW | 1 bar at 9 litres per minute |
| 10.5kW | 1.5 bar at 11 litres per minute |
Some units run at reduced performance from 0.5 bar at 8 litres a minute. Note those are running figures, measured with water flowing, not the static pressure on a gauge with everything shut. That distinction is why showers that were fine on paper disappoint in the flesh.
Higher kW does not mean more water. It means the same water comes out warmer, or more water comes out at the same temperature. In winter, when the incoming mains is coldest, an 8.5kW unit will feel noticeably weaker than it did in August. That is physics, not a fault, and it is worth spending the difference on a higher rating if the supply and the electrics allow it.
The electrical side, and what is notifiable
An electric shower needs its own dedicated circuit from the consumer unit, correctly sized, with a means of isolation.
Installing a new electric shower is always notifiable building work, because installing a new circuit is notifiable in its own right. Separately, a bathroom is a special location, and any addition or alteration to an existing circuit in a special location is notifiable too. The special location runs 2.25 metres vertically and 0.6 metres horizontally from the edge of the bath or shower tray, or 1.2 metres from the centre of the shower head where there is no tray.
Like for like replacement of an existing shower on an existing circuit, and repairs and maintenance, are not notifiable.
All circuits in the location need 30mA RCD protection, and that means all of them, lighting and the heated towel rail included, not just the shower. Fittings need to be at least IPX4 in zones 1 and 2.
On cable size, we are going to disappoint anybody looking for a number. It is a design calculation under BS 7671, based on the design current, the installation method, grouping, ambient temperature, whether the cable runs through insulation, and the volt drop over the length of the run. Websites quoting “10mm for an 8.5kW” are giving you a common outcome, not a rule, and on a long run through a hot loft that common outcome is undersized. We calculate it for the actual installation.
Mixer, thermostatic and digital
A plain manual mixer blends hot and cold on one control. Cheap, and it will change temperature when somebody runs a tap.
A thermostatic mixer holds the set temperature and shuts down if the cold supply fails. This is what we fit as standard, and on any installation used by children, older people or anybody with reduced sensation it is not optional in our view.
On the standards: TMV2 valves are certified against BS EN 1111:2017 for high pressure or BS EN 1287:2017 for low pressure, and are the domestic specification. TMV3 is verified against the NHS performance specification D 08 and is for high risk areas of healthcare premises. TMV3 in a normal house is over specification, and anybody selling it to you as a domestic requirement is adding cost for nothing.
Note the scope of the statutory limit carefully, because it is misquoted everywhere: Approved Document G requires the hot water supply to a bath to be limited to a maximum of 48°C by an in line blending valve or equivalent, and that control should not be easily alterable by the user. That is a bath requirement. It is not a shower one.
Digital showers put the valve out of sight, usually in the loft or a cupboard, with a control panel in the shower. They are excellent and they need somewhere accessible to put the processor, because when it eventually needs attention nobody wants to be cutting a ceiling open.
Hard water, which is the other thing nobody plans for
Every supply zone across our patch is well over 200 mg per litre. Hitchin is published at 368, Stevenage at 320 and the Cambridge Rural zone covering Sawston at 318. Anything above 300 is classed as very hard.
What that does to a shower: it scales the thermostatic cartridge, which is why a shower that held temperature perfectly for three years suddenly starts wandering; it blocks the head, which is usually mistaken for a pressure problem; and it fogs the glass permanently if it is not wiped.
So we specify a head that can be descaled or has clearable nozzles, we fit isolation valves either side of the valve so the cartridge can be serviced without draining anything, and where the whole house warrants it we will talk to you about a softener. On a shower, scale is not a maintenance detail. It is the thing that will eventually fail it.
What we do
Measure the running pressure and flow rate at the point the shower will be fed from, before recommending anything. Confirm the hot water system and what it can actually deliver. Check the electrical supply and what the board can take. Then specify.
Installation includes proper waterproofing behind the tiles rather than relying on grout, isolation valves so future servicing does not mean draining the house, and the electrical work certified through the correct route.
Book a survey
Call 01462 506 374 or tell us what you have and what you want. Across Hertfordshire, Bedfordshire and Cambridgeshire. Gas Safe registered, 956889.
Frequently asked questions
Can I fit an electric shower, a mixer or a pumped shower?
It depends on your water system. A combi gives you mains pressure hot and cold and suits a mixer, but it cannot be pumped. A vented cylinder with a loft tank is gravity fed and usually needs a pump. An unvented cylinder gives you mains pressure and needs neither.
Why does my shower go cold when someone runs a tap?
On a combi, because the boiler can only heat so much water at once and something else is taking it. On a gravity system it is usually pressure loss rather than temperature. A thermostatic valve protects you from scalding but it cannot create flow that is not there.
Can I have a pump on my combi boiler?
No. Pumping the outlet of a combi is not permitted and it will not work properly anyway. If you want more from a combi the answer is either a better flow rate into the property or a change of hot water system, and we will be straight with you about which.
What about a mains booster pump?
A booster on the incoming main is possible but it is regulated. The approved contractor exemption does not cover a booster drawing more than 12 litres per minute, and above that you need consent from the water undertaker. We check that before quoting, not after.
How long does a shower installation take?
A like for like replacement is usually half a day. Moving the position, changing the type, or going from gravity to pumped means new pipework and often tiling to make good, which is one to two days.
Will hard water ruin the new one?
It will scale it eventually. A thermostatic cartridge in this area will last far longer with a scale reducer on the supply, and a shower head that can be descaled easily is worth choosing at the outset.
Areas we cover
We install showers across the whole of our patch.
- Hitchin
- Stevenage
- Letchworth
- Baldock
- Royston
- Biggleswade
- Sandy
- St Neots
- Bedford
- Luton
- Dunstable
- Harpenden
- St Albans
- Welwyn Garden City
- Hertford
- Ware
- Hemel Hempstead
- Hatfield
- Potters Bar
- Cambridge
- Shefford
- Stotfold
- Arlesey
- Knebworth
- Flitwick
- Ampthill
We work across Hertfordshire, Bedfordshire and Cambridgeshire from our base in Stevenage. If your village is not listed, ring 01462 506374 and we will tell you honestly whether we reach you.
Related: bathroom installations, wet rooms, bathroom repairs, unvented cylinders and accessible bathrooms.
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Vantage Plumbing and Heating covers Hertfordshire, Bedfordshire and the surrounding areas. Call and talk to an engineer, or send us the details and we will come back to you with a price.
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