Independent comparisons. We may earn from shop links. More info

80 litre hot water cylinder: which system the title is selling

Updated: 21 October 2026

You searched for an 80 litre hot water cylinder because a flat or a one-bathroom home needs stored hot water, and the results mix two machines that share a volume and not a system. An indirect cylinder sits on a boiler or a heat pump, with a coil inside. The five amazon.co.uk listings in our [80 litre hot water cylinder comparison](/hub/hot-water/80-litre-hot-water-cylinder) are wall-mounted electric stores, each with its own element. Peter F. compared those listings, read on 20 October 2026, with 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 searched for an 80 litre hot water cylinder because a flat or a one-bathroom home needs stored hot water, and the results mix two machines that share a volume and not a system.

Our top picks

TESY TESY 80 litre BiLight vertical

Best overall

TESY TESY 80 litre BiLight vertical
8.8/10about £234.99
View offer
Eldom Eldom Spectra 80 litre

Best value

Eldom Eldom Spectra 80 litre
8.6/10about £189.00
View offer
THERMEX Thermex Digital 80 litre Wi-Fi

Rank 3

THERMEX Thermex Digital 80 litre Wi-Fi
0.0/10about £177.10
View offer
On this page
  1. 1.Electric wall store or boiler cylinder
  2. 2.What £177 to £250 is buying in this set
  3. 3.Fields that contradict themselves
  4. 4.Rules that the price does not remove

Electric wall store or boiler cylinder

A direct store heats water with a built-in element. An indirect store is heated by a boiler or a heat pump through a coil. None of these five listings shows a boiler coil. If the quote says indirect, an airing cupboard, and a gas or oil boiler, a wall heater between £177.10 and £249.99 is the wrong product even when 80 litres matches. Walk away when the installer specified a coil. Stay when the home is on electric heating. Which way the shell faces is on the vertical or horizontal page.

What £177 to £250 is buying in this set

Listing-file prices run from the Thermex at £177.10 and the Eldom at £189.00 to the horizontal TESY at £229.99, the plain TESY at £234.99, and the Wi-Fi TESY at £249.99. Heatandplumb’s Ariston Pro1 Eco at £518.95, and City Plumbing’s Hyco Powerflow at £576.77, are price context, not rows here. The horizontal TESY is cylinder only and names a 3 bar valve and a 1.5 mm cable you still need. The Wi-Fi TESY includes a bracket, not the bolts. The plain TESY says cylinder. The Thermex lists a 3-way valve and a wall anchor. The Eldom states a safety valve. Read the included line before you treat £189 and £520 as the same purchase.
TESY TESY 80 litre BiLight vertical

Testsieger

TESY TESY 80 litre BiLight vertical
8.8/10about £234.99
View offer

Fields that contradict themselves

Trust a figure only when the bullet and the attribute table agree. The plain TESY prints 1,500 kW and a heat-output field of 65°C, and a review on that ASIN describes a 100 litre unit at about 2.5 kW. The Wi-Fi TESY prints 2 kW, then a wattage field of 220 watts. The Eldom attribute line says class C and a bullet says B. Its title says vertical, while the dimensions read 82.5 cm wide by 45.7 cm high. The horizontal TESY prints 3,000 W, and a UK retailer table for a horizontal BiLight 80 lists 2,000 W. Do not merge those into one specification.

Rules that the price does not remove

Approved Document G, for England and Wales, stops stored water exceeding 100°C and requires a visible, safe discharge. An unvented store over 15 litres is notifiable unless a competent-person installer self-certifies. CNC Building Control asks for a record such as Benchmark. A plug or an app does not remove Part G or Part P. A new circuit, and work in a bathroom special location, is notifiable under Approved Document P. Scotland and Northern Ireland use their own standards. For load profile L, retained Regulation 812/2013 puts class C at 37% up to 50% water-heating efficiency and class B at 50% up to 75%. The label counts standing losses. Where you stop is on the installation page.

Common questions

Is this the same thing as the cylinder on a combi or system boiler?
No. A combi boiler often has no storage cylinder at all. A system boiler usually heats an indirect cylinder through a coil. The five listings here are direct electric wall stores of about 80 litres, with their own element and no coil in the listing files. If your quote names a coil, a loft cistern, or a boiler primary circuit, leave this set. A matching volume does not make the machines the same.
Which energy class do I believe when the bullet and the table disagree?
Use the attribute line, and treat a conflicting bullet as unset. On the Eldom the attribute line says C and a bullet says B. For load profile L under retained Regulation 812/2013, class C means 37% up to 50% water-heating efficiency and class B means 50% up to 75%. That letter is not a claim that the element wastes half the electricity. If the two lines disagree, you do not yet know the label that will be on the unit.
Does the box include the unvented kit?
Often it does not. The horizontal TESY is cylinder only and names a 3 bar valve and a 1.5 mm cable as required. The Wi-Fi TESY includes a wall bracket and not the bolts. The plain TESY says cylinder, and a UK review reports no fittings and no cable. The Thermex includes a 3-way safety valve and a wall anchor. The Eldom states a safety valve. A mentioned valve is not a full unvented kit.
Can I ignore Building Regulations if the heater has a plug or an app?
No. An unvented store over 15 litres is notifiable in England and Wales unless a competent person self-certifies. Approved Document P still treats a new circuit, and work in a bathroom special location, as notifiable. A lead with a plug may change whether that particular connection is notifiable. It does not take a fixed 80 litre store out of Part G. The Thermex network-operator bullet is not a UK exemption.
Are German reviews on the Eldom a UK reliability record?
No. The Eldom star line is 4.3 from 39 reviews. Two bodies in the listing file are marked United Kingdom, and they point opposite ways: one says it heats reasonably quickly, and one says it is not fit for purpose. The other written reviews are marked Germany. Those buyers were not describing a UK unvented install, a UK discharge, or a UK competent-person certificate. Do not read them as one.

Related pages

Best 80 litre cylinder

One bathroom

80 litre hot water cylinder

Install an 80 litre electric water heater: the checks

Vertical or horizontal hot water cylinder: which fits

Sources

Public UK sources named below. amazon.co.uk prices, stars and review counts on these five listings were taken from the listing files read on 20 October 2026. Page updated 21 October 2026.

  1. Approved Document G (2024 amendments) (retrieved 20 October 2026)
  2. Approved Document P (2013) (retrieved 20 October 2026)
  3. HSE hot and cold water (retrieved 20 October 2026)
  4. HSE cylinder checks (retrieved 20 October 2026)
  5. Retained Regulation 812/2013 (retrieved 20 October 2026)
  6. GOV.UK energy labelling of products (retrieved 20 October 2026)
  7. Hot Water Association sizing (retrieved 20 October 2026)
  8. TESY BiLight 80 datasheet (retrieved 20 October 2026)