The Ariston Velis Pro 45 Litre is an unvented, wall-hung electric storage water heater built around Ariston's unique twin-tank design. With a 1.5 kW dual Incoloy enamelled element, it operates on a standard 13A circuit — making it ideal for mobile homes, glamping pods, cabins, and leisure installations where an 16A dedicated circuit may not be available. The twin-tank structure delivers a V40 of 77 litres of usable hot water — up to 16% more than a conventional single-tank unit — and is shower-ready in approximately 60 minutes. At just 27 cm deep it is one of the slimmest unvented cylinders available. Supplied with a full unvented installation kit and a 5-year warranty.
45L / V40 77L
Nominal / usable
1.5 kW
Element (13A rated)
60 min
Shower-ready (ΔT=45°C)
⚠ 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 Velis Pro — Leisure & Low-Power Installations — The Velis Pro draws a maximum of 1.5 kW, making it compatible with 13A single-phase circuits including caravan/site hookup supplies. For domestic mains installations where a faster reheat (3 kW) and Wi-Fi scheduling are required, see the Velis Tech Wi-Fi.
Features & Benefits
✔ Twin Tank — Up to 16% More Hot Water
Ariston's twin-tank design reduces thermal stratification, keeping more stored water at full temperature. The result is a V40 of 77 litres of usable hot water from a 45L nominal tank — up to 16% more than a conventional same-capacity unit. Shower-ready in approximately 60 minutes.
✔ Eco Evo — Smart Energy Saving
The Eco Evo function learns from daily usage patterns and adjusts the heating schedule to deliver hot water when actually needed — avoiding unnecessary reheating and saving up to 14% on electricity bills. Configured via the on-unit display.
✔ Titanium-Coated Twin Tank
The inner tank structure is coated with Ariston's titanium enamel for corrosion and scale resistance. The electronic anode provides active protection without requiring physical inspection or replacement.
✔ ABS Safety + Anti-Legionella
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.
✔ 1.5 kW — Runs on a 13A Circuit
The maximum draw of 1.5 kW means the Velis Pro can be used in locations where a dedicated high-current circuit is not available — including leisure sites, outbuildings, and retrofit installations alongside other loads on a shared circuit.
✔ Ultra-Slim 27 cm Depth
At 275 mm deep × 405 mm wide × 776 mm tall, the Velis Pro fits in airing cupboards, loft spaces, and confined wall locations where conventional cylinders cannot.
✔ Soft-Touch HMI Display
The on-unit LED display shows current water temperature, hot water availability, and heating status. Shower-ready alerts are displayed on screen. No app or Wi-Fi required for operation.
✔ Supplied with Unvented Kit
Includes a 12-litre expansion vessel, tundish, and pressure reducing valve (KIWA certified) for UK unvented installation. UKCA marked.
Technical Specifications
| Brand / Model |
Ariston Velis Pro 45L |
| Part Number (inc. unvented kit) |
4018075 | 3626305 |
| Nominal Capacity |
45 litres |
| V40 (usable hot water at 40°C) |
77 litres |
| Heating Element |
Dual 1.5 kW Incoloy enamelled (max. 1.5 kW at any one time) |
| Reheat Time (ΔT = 45°C) |
60 minutes |
| Standing Heat Loss @ 65°C |
0.96 kWh/24h |
| Max Working Temperature |
65°C |
| ErP Energy Rating |
B |
| ErP Tapping Profile |
M |
| IP Protection |
IPX4 |
| Wi-Fi / App |
No — on-unit display only |
| Display |
LED soft-touch HMI (Shower-ready on screen) |
| Tank Protection |
Electronic anode + titanium enamel coating |
| Anti-Legionella |
Automatic monthly 65°C cycle |
| Installation |
Vertical wall-hung (unvented — G3 qualification required) |
| Dimensions (H × W × D) |
776 × 405 × 275 mm |
| Weight (empty / full) |
21 kg / 66 kg |
| Voltage / Frequency |
230–240 V / 50–60 Hz |
| Unvented Kit Included |
Yes — 12L expansion vessel, tundish, PRV (KIWA) |
| Certification |
UKCA |
| Warranty |
5 years |
Frequently Asked Questions
Why choose the Velis Pro over the Velis Tech Wi-Fi?
The Velis Pro is the right choice where a 1.5 kW maximum draw is required — in leisure settings (mobile homes, glamping pods, cabins) or locations where a dedicated 16A circuit cannot be installed. It shares the same twin-tank design and ErP B rating as the Wi-Fi model. If you have a standard domestic mains connection, prefer faster reheating, or want remote app control, the Velis Tech Wi-Fi is recommended.
Does it require a G3-qualified installer?
Yes — this is an unvented hot water storage appliance. Installation must be carried out by someone holding a current Part G (G3) unvented qualification and must be notified to Building Control. The supplied expansion vessel, tundish, and PRV must be correctly installed in accordance with Building Regulations Approved Document G and BS 7074.
What does V40 mean?
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 Velis Pro 45L, V40 = 77 litres — more than the nominal tank size due to the twin-tank's effective stratification management.
