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| KW Output | 30 Kw |
|---|---|
| Manufacturer Warranty | 2 Years (T&C’s Apply) |
| Type | Water Heater |
| Fuel Type | Natural Gas |
| DHW Flow Rate | 2.5 Kw |
| Flue | Horizontal Flue |
| Depth | 187mm |
| Width | 345mm |
| Height | 570mm |
| Shop By Brand | Ariston |
| Manufacturer Part No | 3632533 |
Home > Boilers & Water Heating > Gas Water Heaters > Ariston NEXT EVO X 16L Gas Fired Water Heater With Horizontal Flue
A wall-mounted gas instantaneous water heater delivering 16 litres per minute of hot water on demand. Ultra compact at just 165mm deep. Low NOx Class 5 lean-rich burner. Built-in ECO mode, temperature stabilisation and post-ventilation safety system. Natural gas. Horizontal flue kit included.
Delivers 16 litres per minute at a 25°C temperature rise. Enough to run a shower and a hand basin simultaneously. Heats water on demand — no stored water, no standing heat loss, no cylinder required.
One of the slimmest gas water heaters available. At 165mm deep it protrudes less than a standard radiator, making it ideal for tight spaces such as utility rooms, understairs cupboards, airing cupboards and commercial back-of-house areas.
The oxygen-rich lean-rich burner achieves NOx Class 5 — the highest emissions standard. Meets current and anticipated future Building Regulations for NOx emissions. Significantly cleaner than older Class 3 or unclassified water heaters.
ECO mode limits the output temperature between 35°C and 45°C. Perfect for summer use when incoming water is warmer and full power is unnecessary. Reduces gas consumption and minimises lime scale formation in the heat exchanger, extending product life.
Pure copper heat exchanger with oxygen-free construction for superior thermal conductivity and long-term corrosion resistance. Copper is the gold standard for gas water heater heat exchangers — efficient, durable and proven over decades.
Minimum working water pressure of just 0.2 bar and minimum flow rate of 2.5 litres per minute. Suitable for properties with low mains water pressure or where water is supplied from a gravity-fed tank system — situations where many instantaneous heaters would not activate.
Continues to run the fan after burner shutdown to clear any residual combustion gases from the heat exchanger and flue path before the unit shuts down completely.
Automatically shuts off the gas supply if the heat exchanger exceeds safe operating temperature, preventing damage and ensuring user safety.
Monitors the burner flame at all times. If the flame extinguishes unexpectedly, the gas supply is cut off immediately to prevent unburnt gas entering the combustion chamber.
Automatically adjusts the gas valve to maintain a consistent output water temperature even if the incoming cold water temperature or flow rate fluctuates. Prevents scalding and temperature spikes.
| Specification | Detail |
|---|---|
| Product Name | Ariston NEXT EVO X 16L Gas Fired Water Heater With Horizontal Flue |
| SKU / Ariston Code | 3632533 |
| Product Type | Gas Instantaneous Water Heater (Tankless / On-Demand) |
| Fuel Type | Natural Gas (G20) |
| Flow Rate | 16 litres per minute at ΔT 25°C |
| Heat Input (Max) | 28 kW (approx.) |
| Heat Output (Max) | 24 kW (approx.) |
| Height | 650 mm (approx.) |
| Width | 370 mm (approx.) |
| Depth (Wall Projection) | 165 mm |
| Mounting Type | Wall Mounted |
| Heat Exchanger | Oxygen-Free Copper |
| Burner Type | Lean-Rich (Oxygen-Rich) — Low NOx |
| NOx Emissions Class | Class 5 (highest standard) |
| ECO Mode | Yes — limits output to 35–45°C |
| Temperature Stabilisation | Yes — built-in automatic modulation |
| Minimum Water Pressure | 0.2 bar |
| Maximum Water Pressure | 10 bar |
| Minimum Flow Rate to Activate | 2.5 litres/min |
| Gas Connection | 1/2 inch BSP |
| Cold Water Connection | 1/2 inch BSP |
| Hot Water Connection | 1/2 inch BSP |
| Flue Type Supplied | Horizontal flue kit included |
| Flue Diameter | 60 mm (typical for this model — confirm on receipt) |
| Post-Ventilation | Yes — fan continues after burner shutdown |
| Overheat Protection | Yes — overheat sensor with gas cut-off |
| Flame Supervision | Yes — automatic flame failure device |
| Ignition Type | Electronic / Battery (confirm on receipt) |
| Empty Weight | Approx. 13 kg (unit only) |
| Packaged Weight | Approx. 15 kg (with flue kit) |
| Suitable For | Domestic hot water only — not for central heating |
| Installation | Must be installed by a Gas Safe registered engineer |
| Manufacturer | Ariston |
| Requirement | Detail |
|---|---|
| Installer | Gas Safe registered engineer required by law |
| Gas Supply | Natural Gas (G20) — 22mm pipe from meter recommended for 28kW input |
| Cold Water Supply | Mains cold water — minimum 0.2 bar dynamic pressure |
| Gas Pipe Size | 22mm from meter or local manifold (do not reduce to 15mm) |
| Flue | Horizontal flue kit included. Must terminate per Document J of Building Regulations |
| Flue Termination | Minimum clearances from windows, air bricks, boundaries and rooflines per Approved Document J |
| Wall Mounting | Solid brick or block wall required. Plasterboard/dot-and-dab walls need additional reinforcement |
| Electrical Supply | May require a fused spur depending on ignition type — confirm on receipt of unit |
| Ventilation | Combustion air drawn from the room. Ensure adequate ventilation per BS 5440-2 and Building Regulations |
| Water Connections | 1/2 inch BSP — isolation valves recommended on both cold inlet and hot outlet |
| Building Regulations | Notification to Local Authority Building Control (or Gas Safe self-certification) is required |
Looking for a 16 litre gas instantaneous water heater? The Ariston NEXT EVO X 16L (3632533) is a natural gas wall-mounted tankless water heater with horizontal flue, Low NOx Class 5 burner, ECO mode, 165mm depth and 0.2 bar minimum pressure. Also found via: Ariston Next EVO X 16L gas water heater, 3632533, gas instantaneous water heater 16L natural gas, tankless gas water heater UK, wall mounted gas water heater 16 litre, Ariston Next Evo X horizontal flue, low NOx gas water heater, ultra compact gas water heater 165mm, Ariston gas water heater with flue kit, unvented gas water heater 16L, domestic hot water gas heater UK.
| Free Delivery | Free express delivery on all orders over £500 to UK mainland addresses |
| Standard Delivery | Charged on orders under £500 — calculated at checkout |
| Delivery Area | UK mainland only. We do not deliver to Northern Ireland, Scottish Highlands, Channel Islands or overseas |
| Lead Time | Maximum 14 working days from order. Call 01282 429061 to confirm availability |
| Finance Options | Spread the cost with Klarna or Clearpay — available at checkout |
| Returns Window | 14 days from receipt of goods |
| Return Postage | Cost of returning goods is borne by the customer. Original delivery charges are non-refundable |
| Restocking Charge | A 25% restocking charge may apply to non-faulty returns |
| Condition | Items must be unused and in original, unopened packaging |
| Faulty Items | Confirmed faulty = 100% of original product value credited |
| Guarantee | Backed by Ariston manufacturer warranty against manufacturing defects |
