Ariston Pro1 Eco 100L Electric Storage Unvented Water Heater – 3820021

The Ariston Pro1 Eco 100L Electric Storage Unvented Water Heater provides stored hot water for homes, flats and light commercial properties. Its vertical wall-mounted design also saves valuable floor space.

This model has a nominal size of 100 litres and an actual capacity of approximately 95 litres. In addition, its powerful 3kW element heats the stored water efficiently. Ariston quotes a heat-up time of around 128 minutes for a 45°C temperature rise.

WaterPlus technology keeps incoming cold water near the bottom of the tank. Therefore, it reduces mixing with the stored hot water above. Ariston states that this technology can provide up to 16% more available hot water under its test conditions.

Meanwhile, the Eco Evo function learns normal hot water habits and adjusts the heating pattern. As a result, it can help reduce energy use while keeping hot water ready when it is usually needed.

Product Guides and Further Information

• Download the Ariston Pro1 Eco installation manual
• View the Ariston Pro1 Eco product page

Ariston Pro1 Eco 100L Water Heater Features

• Electric storage unvented water heater
• Product code: 3820021
• Nominal size: 100 litres
• Actual capacity: approximately 95 litres
• Mixed hot water capacity at 40°C: approximately 130 litres
• Powerful 3kW heating element
• Vertical wall-mounted installation
• Electronic thermostat and temperature display
• Shower Ready indicator
• WaterPlus technology for up to 16% more available hot water
• Eco Evo function can help reduce energy use
• T-MAX function for unexpected hot water demand
• Titanshield tank protection
• Magnesium anode helps resist corrosion
• Anti-legionella function
• Anti-overheating and anti-freezing protection
• Dry-heating safety diagnosis
• Supplied with a full unvented installation kit
• ErP energy rating: B
• IPX3 protection rating
• Up to five-year tank warranty
• Up to two-year electrical components warranty

Technical Specification

• Brand: Ariston
• Range: Pro1 Eco
• Product code: 3820021
• Heater type: Electric storage unvented water heater
• Nominal capacity: 100 litres
• Actual capacity: Approximately 95 litres
• Mixed hot water at 40°C (V40): Approximately 130 litres
• Power rating: 3kW
• Supply voltage: 230–240V
• Maximum operating temperature: 65°C
• Heat-up time: Approximately 128 minutes for a 45°C rise
• Maximum inlet pressure: 12 bar
• Maximum working pressure: 6 bar
• Expansion valve setting: 6 bar
• Expansion vessel pre-charge: 3.5 bar
• Temperature and pressure relief valve setting: 7 bar
• Standing heat loss: Approximately 1.434kWh per 24 hours
• ErP rating: B
• Load profile: M
• IP rating: IPX3
• Installation position: Vertical wall mounting
• Empty weight: Approximately 26kg
• Full weight: Approximately 121kg

Water Heater Dimensions

• Height: Approximately 888mm
• Maximum width: Approximately 480mm
• Cylinder diameter: Approximately 470mm

Before ordering, check the available wall space and allow room for valves, pipes and future servicing. Furthermore, the wall and mounting fixings must safely support the heater’s full weight of approximately 121kg.

What Comes with the Water Heater?

• 1 x Ariston Pro1 Eco 100L water heater
• 1 x 12-litre expansion vessel
• 1 x pressure-reducing valve
• 1 x tundish
• Required safety and pressure-control components
• Installation and user instructions

Ariston may update the supplied kit without notice. Therefore, check the latest product literature before ordering. Your installer may also need extra pipes, valves, electrical controls and fittings to suit the property.

Where Can You Use the Ariston Pro1 Eco 100L?

The Ariston Pro1 Eco 100L may suit flats, homes, offices, shops and light commercial premises. For example, it can provide stored hot water where a boiler-fed hot water cylinder is not available or suitable.

Its larger capacity may support several hot water outlets. However, the correct heater size depends on the number of users, bathrooms, showers, baths and taps. Therefore, always ask a qualified installer to calculate the expected demand before ordering.

How Does WaterPlus Technology Work?

WaterPlus technology directs incoming cold water towards the bottom of the tank. As a result, it limits mixing between the incoming water and the stored hot water.

Ariston states that this process can provide up to 16% more available hot water under its test conditions. However, the amount available during normal use will depend on the inlet temperature, thermostat setting and outlet flow rate.

What Does the Eco Evo Function Do?

The Eco Evo function learns common hot water habits and plans the heating times around them. Therefore, it avoids keeping the entire tank at a high temperature when hot water demand is low.

Ariston states that Eco Evo can reduce energy use by up to 14% under its test conditions. However, actual savings will vary according to water use, electricity prices and the selected temperature.

T-MAX and Shower Ready Functions

The T-MAX function temporarily raises the water temperature when extra hot water is needed. Once the cycle ends, the heater returns to its previous setting. Therefore, users can meet occasional higher demand without permanently increasing the set temperature.

In addition, the Shower Ready indicator shows when enough hot water should be available for a shower. This feature makes it easier to manage hot water use throughout the day.

Built-In Safety Features

The Absolute Safety System includes anti-overheating, anti-freezing and dry-heating protection. These features help protect the heater when it detects unsafe operating conditions.

In addition, the anti-legionella function automatically raises the stored water temperature to 65°C at set intervals. This cycle helps control the risk of legionella bacteria developing inside the tank.

Why Choose the Ariston Pro1 Eco 100L?

• Useful storage capacity: The larger tank suits properties with regular hot water demand.
• Fast heating: The 3kW element provides efficient heat-up and recovery.
• More usable hot water: WaterPlus technology helps reduce mixing inside the tank.
• Simple controls: The electronic display makes temperature adjustment straightforward.
• Energy-saving function: Eco Evo adapts heating to normal usage patterns.
• Strong tank protection: Titanshield and a magnesium anode help resist corrosion.
• Space-saving installation: The vertical wall-mounted design leaves the floor clear.
• Unvented kit included: The package contains the main pressure and safety controls.

Why Buy from SNH Tradecentre?

• Competitive prices: We aim to offer excellent value across the Ariston range.
• Helpful advice: Our team can help you compare heater sizes and power ratings.
• Genuine Ariston products: Buy from an established plumbing and heating merchant.
• Clear product information: We provide useful specifications to help you order confidently.
• Trade and public welcome: We supply installers, landlords, businesses and homeowners.
• UK-based support: Contact our team if you need help with the product or delivery.
• Independent merchant: SNH Tradecentre is based in Birchington, Kent.

Need Help Choosing?

Not sure whether this 100-litre heater will meet your needs? Call SNH Tradecentre on 01843 842727. Our team can help you compare the Ariston Pro1 Eco range before you order.

Read Reviews from SNH Tradecentre Customers

See what customers say about our service, products and advice on the SNH Tradecentre Google Reviews page.

Read SNH Tradecentre customer reviews on Google

Installation Requirements

A qualified and competent unvented hot water installer must fit and commission this water heater. In addition, a qualified electrician must complete the electrical connection in line with current wiring rules.

The installer must use the supplied unvented kit and provide a safe discharge route. They must also check the incoming water pressure, flow rate and wall strength before starting the installation.

Furthermore, the installer must fill the tank completely before switching on the power. Running the heating element without water may damage it and affect the warranty.

The installation must meet Part G3 of the Building Regulations in England and Wales. Installers must also follow the rules that apply in Scotland and Northern Ireland, together with Ariston’s latest instructions.

Warranty Information

Ariston currently offers up to five years of warranty cover on the tank and up to two years on electrical components. However, registration, professional installation and servicing conditions apply.

Register the appliance with Ariston within 30 days of installation. In addition, keep the purchase invoice and installation records. Always check Ariston’s current warranty terms for complete details and exclusions.

Frequently Asked Questions

What is the actual capacity of the Ariston Pro1 Eco 100L?

Ariston markets this appliance as a 100-litre heater. However, its stated actual water capacity is approximately 95 litres.

How much mixed hot water can it provide?

Ariston gives this model a V40 figure of approximately 130 litres. This figure represents the estimated mixed hot water available at 40°C under test conditions.

How powerful is the heating element?

This model has a 3kW electric heating element. Therefore, it provides a faster heat-up time than many lower-powered storage heaters.

How long does the heater take to warm up?

Ariston states a heat-up time of around 128 minutes for a 45°C temperature rise. However, the actual time will depend on the incoming water temperature and selected setting.

What is WaterPlus technology?

WaterPlus keeps incoming cold water near the bottom of the tank. Therefore, it reduces mixing with stored hot water and can provide up to 16% more available hot water under Ariston’s test conditions.

Does the heater include an unvented kit?

Yes. Product code 3820021 includes a full unvented kit with a 12-litre expansion vessel, tundish and pressure-reducing valve. Your installer may still need additional pipework and fittings.

Can the Ariston Pro1 Eco 100L supply a shower?

It may supply suitable showers and other hot water outlets. However, an installer must check the expected demand, shower flow rate and incoming mains supply before confirming suitability.

Can I install the heater horizontally?

No. This model is designed for vertical wall mounting. The installer must follow the orientation and clearance requirements in the current Ariston installation manual.

How much does the heater weigh when full?

The heater weighs approximately 26kg when empty and around 121kg when full. Therefore, the wall and mounting fixings must safely support the full operating weight.

Who can install this unvented water heater?

A competent unvented hot water installer must fit and commission it. In addition, a qualified electrician must complete the electrical work.

Order the Ariston Pro1 Eco 100L Water Heater

Choose the Ariston Pro1 Eco 100L Electric Storage Unvented Water Heater 3820021 for reliable stored hot water, 3kW heating, electronic controls and a complete unvented installation kit.

Before ordering, ask your installer to confirm the heater size, electrical supply, incoming water pressure and installation position.

Manufacturers may change specifications, supplied parts and warranty terms. Therefore, check the latest Ariston literature before ordering or installing this product.