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50 litre hot water cylinder buying guide

Updated: 21 October 2026

You are choosing a 50 litre hot water cylinder for a UK flat or a single outlet, and the capacity on the title is the easy part. The harder part is whether the tank, the wall, the circuit and the box actually match the job before you look at stars. This 50 litre hot water cylinder buying guide walks those checks in order. The four amazon.co.uk listings we kept, from £159.99 to £219, are ranked on the [50 litre hot water cylinder comparison](/hub/hot-water/50-litre-hot-water-cylinder). Peter F. wrote these notes on 20 October 2026 from those listings and public UK sources. There was no lab test. A qualifying amazon.co.uk purchase can earn a commission at no extra cost to you.

You are choosing a 50 litre hot water cylinder for a UK flat or a single outlet, and the capacity on the title is the easy part.

Our top picks

Eldom Eldom Favourite 50 litre Wi-Fi

Best overall

Eldom Eldom Favourite 50 litre Wi-Fi
8.6/10about £189.35
View offer
Eldom Eldom Spectra 50 litre vertical

Rank 2

Eldom Eldom Spectra 50 litre vertical
7.8/10about £175.00
View offer
TESY TESY BiLight 50 litre horizontal

Best value

TESY TESY BiLight 50 litre horizontal
7.4/10about £159.99
View offer
On this page
  1. 1.What a 50 litre cylinder is in this comparison
  2. 2.Size the job before the brand
  3. 3.Watts, the label, and the box
  4. 4.What still needs an installer

What a 50 litre cylinder is in this comparison

In this set, a 50 litre cylinder means a direct electric storage heater on the wall, with its own element. It is not an indirect cylinder waiting for a boiler, and it is not a 50 L/h catering boiler. If the title talks about cups, tea or a drip tray, you are on the wrong page. A 3 kW Ariston Pro1 Eco 50 litre listing we saw at £478.95, and UK trade kits around £395 to £430 including VAT, are context only. Do not assume the £159.99 to £219 boxes contain the same expansion vessel and 3 kW element.

Size the job before the brand

The Hot Water Association sketches about 35 to 45 litres of stored hot water per occupant. Ariston UK describes 45 to 50 litres as enough for a shower, and points towards 80 litres when several showers follow. Those are rules of thumb, not a measurement we took in a flat. A bath near 100 litres of water at 40 °C usually knocks 50 litres out. If you want one shower and can wait to reheat, the minutes are on the shower page. Measure the void on the horizontal or vertical page, because turning a vertical tank on its side is not a way to save height.
Eldom Eldom Favourite 50 litre Wi-Fi

Testsieger

Eldom Eldom Favourite 50 litre Wi-Fi
8.6/10about £189.35
View offer

Watts, the label, and the box

The listings in this set are 1.5 kW or 2 kW heaters. Read the wattage in the title and then the specification cells, because they do not always agree. On the Spectra listing the title says 1.5 kW, while a wattage cell says 1381 KW and a heat-output cell says 15 kW. A B&Q page prints 1,381 kWh a year, which makes that Amazon cell look like a mis-read of annual consumption, but the amazon.co.uk table is what you are buying from. In this set only the TESY prints class C, profile M and 1,418 kWh together. The Favourite shows class B and does not print the annual kWh. The GEESEN shows class A with no kWh and no profile. A lone A is not a fuller label than the TESY line.

What still needs an installer

A 50 litre mains-pressure store is well over the 15 litre line. LABC describes storage over 15 litres as controlled work that you notify. CNC Building Control says an unvented store over 15 litres needs a competent person, and a Benchmark-style record. The Water Supply (Water Fittings) Regulations 1999 require a safety-device arrangement on an unvented water heater, other than an instantaneous heater not over 15 litres. Check the wall, and whether the valve and the fixings are in this box, before that visit. The TESY listing asks for a 16 A fused spur. A new circuit, or work in a bathroom zone, is still notifiable. If the relief valve discharges on first heat, that outlet has to run to a safe, visible point. The sequence is on the installation page.

Common questions

Is 50 litres the right size for one person?
If a second person needs a shower before the tank has reheated, look at a larger cylinder rather than a different badge on a 50 litre listing. The 35 to 45 litres per person figure is a rule of thumb, not a shower-length guarantee.
Should I look at the energy letter or the annual kWh?
Use both, and treat a letter with no kWh as unfinished. For profile M, the class bands put B at 39% up to under 65% water-heating efficiency, and C at 36% up to under 39%. The maker's fiche for WV05039EW quotes 1,169 kWh, which is manufacturer data, not the Amazon cell.
Does the box include a valve, a cable and wall bolts?
It depends which listing you open. The TESY includes a wall bracket and says the fixing bolts are not included. The Favourite lists an inlet and safety valve. The Spectra lists a 3-way inlet valve and does not list wall screws. The GEESEN lists a safety valve, screws, a drip pipe and an NTP 1/2 adapter. None of these is a full UK kit with an expansion vessel and a 3 kW element.
Is 1.5 kW enough, or do I need 3 kW?
For a single store that can reheat while you are out, the 1.5 kW and 2 kW titles in this set are the products on offer. A 3 kW 50 litre kit with an expansion vessel is a different purchase. Do not plan the circuit from the Spectra cell that says 1381 KW or the cell that says 15 kW. Ask the installer to confirm the element on the data plate before the spur is sized.
What is load profile M?
Load profile M is the medium usage pattern declared on the water-heater energy label under Regulation (EU) No 812/2013. The annual kWh figure is calculated for that pattern, which is why a class letter without the profile and the kWh is hard to compare. The TESY listing is the one here that states profile M in public on the amazon.co.uk page.
Do I need a separate expansion vessel?
Not as a blanket rule. The Favourite bullets say no expansion vessel is needed. That claim belongs to that listing. Ferroli and Ariston packages around £395 to £430 including VAT are offered with a vessel in the kit. An installer specification is not cancelled by the Amazon bullet.

Related pages

Best 50 litre cylinder

50 litre hot water cylinder

Is a 50 litre hot water cylinder enough for a shower?

Horizontal or vertical: which 50 litre heater fits

How to install a 50 litre electric water heater safely

Sources

Public UK sources named below, as used for this comparison. amazon.co.uk prices, stars and review counts are the figures on the four listings in the product data. Page updated 21 October 2026.

  1. Approved Document G (2024 amendments) (retrieved 21 October 2026)
  2. HSE hot and cold water systems (retrieved 21 October 2026)
  3. CNC Building Control: hot water cylinder permission (retrieved 21 October 2026)
  4. BSI BS EN 12897:2016+A1:2020 (retrieved 21 October 2026)
  5. Regulation (EU) No 812/2013 on legislation.gov.uk (retrieved 21 October 2026)
  6. Hot Water Association: sizing a hot water cylinder (retrieved 21 October 2026)
  7. Approved Document P 2013 (retrieved 21 October 2026)
  8. IEC 60379:2023 electric storage water heater methods (retrieved 21 October 2026)