The Ariston Pro1 Eco 50 Litre is a wall-mounted unvented electric storage water heater suitable for studios, 1-bedroom flats, and single-bathroom properties. With a 3 kW element, the Pro1 Eco heats from cold in approximately 60 minutes and delivers a V40 of 65 litres — enhanced by Ariston's WaterPlus technology, which provides up to 16% more usable hot water than conventional cylinders of the same size. The Eco Evo function (powered by CoreTech) saves up to 14% on energy bills by learning usage habits, while Titanshield technology protects the tank for long-term durability. Supplied complete with a full unvented installation kit and a 5-year warranty.
50L / V40 65L
Nominal / usable
⚠ Qualified Installation Required (Unvented) — This is an unvented hot water storage appliance. Installation must be carried out by a competent person holding a current Part G (Schedule 2) qualification in unvented hot water storage systems — such as G3 or equivalent — in accordance with Building Regulations Approved Document G. Installation must be notified to the local authority building control or an approved inspector. The supplied unvented kit (expansion vessel, tundish, and pressure reducing valve) must be fitted as part of the installation.
ℹ Supplied with Unvented Kit — Each unit is supplied with a 12-litre expansion vessel, tundish, and pressure reducing valve (KIWA certified) as required for UK unvented installations. All Ariston electric water heaters in this range are UKCA marked.
Features & Benefits
✔ WaterPlus Technology — More Hot Water
Ariston's patented WaterPlus technology minimises the mixing of incoming cold water with stored hot water, maintaining more of the tank volume at temperature. The result is a V40 of 65 litres from a 50L tank — up to 16% more hot water than a conventional equivalent-capacity cylinder.
✔ Eco Evo + CoreTech — Save Up to 14%
The Eco Evo function powered by CoreTech monitors and learns usage patterns, adjusting the heating schedule to deliver hot water only when actually needed. This can reduce electricity consumption by up to 14% per year compared to constant-temperature operation.
✔ T-MAX — Instant Boost for Unexpected Demand
The T-MAX function heats the cylinder to maximum temperature as quickly as possible when unexpected demand requires more hot water than usual — activated via the on-unit display without needing to adjust settings manually.
✔ Titanshield Tank Protection
Ariston's Titanshield technology applies a titanium-reinforced enamel coating to the inner tank surface, providing superior resistance to corrosion and scale compared to standard vitreous enamel. A magnesium sacrificial anode provides additional protection (inspection recommended periodically by the service engineer).
✔ Anti-Legionella + Absolute Safety
Active protection includes Anti-Overheating, Anti-Freezing, and Dry Heating Self-Diagnosis. Once a month, the unit automatically raises tank temperature to 65°C to eliminate Legionella bacteria risk — a requirement under ACOP L8 for domestic hot water systems.
✔ Electronic Temperature Control with Display
The electronic thermostat and digital display allow precise temperature setting and display current water temperature. The Shower-Ready function alerts via on-screen indicator when the cylinder has reached delivery temperature. Simpler operation than mechanical thermostat models.
✔ Premium Insulation
High-density foam insulation minimises standing heat losses (0.92 kWh/24h @ 65°C), keeping the stored water at temperature with less electricity required for periodic reheating.
✔ Ariston Wave Design
The Ariston Wave body shape with white finish provides a clean, contemporary aesthetic suitable for visible installations in utility rooms, plant rooms, and airing cupboards. Connections are standard ½" BSP male at top and bottom.
Technical Specifications
| Brand / Model |
Ariston Pro1 Eco 50L |
| Part Number (inc. unvented kit) |
3820019 |
| Nominal Capacity |
50 litres |
| V40 (usable hot water at 40°C) |
65 litres |
| Rated Power |
3 kW |
| Heat-Up Time (ΔT = 45°C) |
60 minutes |
| Standing Heat Loss @ 65°C |
0.92 kWh/24h |
| Max Working Temperature |
65°C |
| ErP Energy Rating |
B |
| ErP Tapping Profile |
M |
| IP Protection |
IPX3 |
| Thermostat |
Electronic with digital display |
| Tank Protection |
Titanshield enamel + magnesium sacrificial anode |
| Anti-Legionella |
Automatic monthly 65°C cycle |
| Connections |
½" BSP male (hot outlet top, cold inlet bottom) |
| Installation |
Vertical wall-mounted (unvented — G3 qualification required) |
| Dimensions (H × Ø) |
762 mm × 470 mm diameter |
| Weight (empty / full) |
17 kg / 67 kg |
| Voltage / Frequency |
230–240 V / 50 Hz |
| Unvented Kit Included |
Yes — 12L expansion vessel, tundish, PRV (KIWA) |
| Certification |
UKCA |
| Warranty |
5 years |
Frequently Asked Questions
What is the difference between the Pro1 Eco and the Velis Tech Wi-Fi?
The Pro1 Eco is a traditional cylinder-shaped wall-mounted unit — larger in footprint (470 mm diameter), available in 50, 80, and 100 litre capacities, and uses WaterPlus technology (a different mechanism to the twin-tank) with a magnesium anode. The Velis Tech Wi-Fi uses a flat twin-tank design (27 cm deep), is available in 45 and 80 litres, has Wi-Fi connectivity, and uses an electronic anode — making it the better choice for space-constrained installations. The Pro1 Eco is typically preferred where a larger volume (100L) is needed or the rounded cylinder form factor is suitable.
What G3 qualification is needed for installation?
Installation of this unvented hot water storage system must be carried out by a competent person holding a current Part G (Schedule 2) unvented qualification — for example G3, ACS or equivalent. The work must be notified to Building Control. The supplied unvented kit (12L expansion vessel, tundish, and PRV) must be installed correctly, and the temperature/pressure relief valve must drain safely to a suitable discharge point via the tundish.
Does the magnesium anode need replacing?
Yes — unlike the Velis Tech Wi-Fi (which uses an electronic anode requiring no maintenance), the Pro1 Eco uses a traditional magnesium sacrificial anode. This should be inspected periodically — typically as part of an annual service check by a qualified engineer — and replaced when significantly depleted to maintain tank protection. The service interval depends on local water hardness.
What does V40 mean and why is it higher than the tank capacity?
V40 is the ErP test metric for usable hot water at 40°C mixed delivery — higher than nominal capacity because stored hot water is mixed with cold at the tap. For the Pro1 Eco 50L, V40 = 65 litres due to WaterPlus technology.
