Vaillant Ecofit Pure 835 Boiler Instruction Manual
Vaillant Ecofit Pure 835 Boiler
Vaillant Ecofit Pure 835 Boiler Instructions
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Vaillant Ecofit Pure 835 Boiler Specifications
| Feature Category | Specification | Value (VUW 356/6-3 (H-GB)) |
|---|---|---|
| General Data | Gas Category | I2H |
| Diameter of Gas Pipe | 1/2 inch | |
| Diameter of Heating Connections | 3/4 inch | |
| Expansion Relief Valve Connection Pipe (min.) | 15 mm | |
| Condensate Discharge Pipe (min.) | 21.5 mm | |
| G20 Gas Supply Pressure | 2.0 kPa (20.0 mbar) | |
| Gas Flow at P max. – hot water (G20) | 3.8 m³/h | |
| Gas Flow at P max. – heating mode (G20) | 2.7 m³/h | |
| Gas Flow at P min. (G20) | 0.762 m³/h | |
| CE Number (PIN) | CE-0063CP3646 | |
| SAP 2009/2012 Annual Efficiency | 89.7% | |
| Flue Gas Mass Rate (heating mode at P min.) | 3.30 g/s | |
| Flue Gas Mass Rate (heating mode at P max.) | 11.6 g/s | |
| Flue Gas Mass Rate (hot water handling mode at P max.) | 16.1 g/s | |
| Flue Gas Temperature (80 °C/60 °C at P max.) | 82 °C | |
| Flue Gas Temperature (50 °C/30 °C at P min.) | 37 °C | |
| NOx Class | 6 | |
| Product Dimensions (Width) | 390 mm | |
| Product Dimensions (Depth) | 295 mm | |
| Product Dimensions (Height) | 702 mm | |
| Net Weight | 33 kg | |
| Weight when filled with water | 38 kg | |
| Power/Loading G20 | Maximum Heat Output (Heating) | 25 kW |
| Effective Output Range (P) at 40/30 °C | 7.6 to 27.2 kW | |
| Effective Output Range (P) at 50/30 °C | 7.5 to 26.7 kW | |
| Effective Output Range (P) at 80/60 °C | 7.2 to 25.5 kW | |
| Domestic Hot Water Heat Output (P) | 7.1 to 35.0 kW | |
| Maximum Heat Input – heating (Q max.) | 25.7 kW | |
| Minimum Heat Input – heating (Q min.) | 7.2 kW | |
| Maximum Heat Input – hot water (Q max.) | 35.7 kW | |
| Minimum Heat Input – hot water (Q min.) | 7.2 kW | |
| Heating Specific | Max. Flow Temperature Adjustment Range | 10 to 80 °C (default: 75 °C) |
| Maximum Permissible Pressure | 0.25 MPa (2.50 bar) | |
| Nominal Water Flow (ΔT = 20 K) | 1,102 l/h | |
| Nominal Water Flow (ΔT = 30 K) | 876 l/h | |
| Approximate Condensate Volume (50/30 °C) | 2.57 l/h | |
| Domestic Hot Water Specific | Specific Flow Rate (D) (ΔT = 30 K) | 16.5 l/min |
| Specific Flow Rate (ΔT = 35 K) | 14.1 l/min | |
| Minimum Permissible Pressure | 0.03 MPa (0.30 bar) | |
| Maximum Permissible Pressure | 1 MPa (10 bar) | |
| Recommended Pressure | 0.2 MPa (2.0 bar) | |
| Temperature Range | 35 to 60 °C | |
| Maximum Water Flow Rate | 12.0 l/min | |
| Electrics | Electrical Connection | 230 V / 50 Hz |
| Built-in Fuse (slow-blow) | T2/2A, 250V | |
| Max. Electrical Power Consumption | 98 W | |
| Standby Electrical Power Consumption | 3 W | |
| IP Rating | IPX4D |
Vaillant Ecofit Pure 835 Boiler Details
The Vaillant Ecofit Pure 835 combi boiler is designed as an efficient heat generator for closed heating systems and domestic hot water production. Its compact design allows for versatile installation, including within zones 2 or 3 of rooms containing a bath or shower, adhering to relevant wiring and building regulations in Great Britain and Ireland.
This product prioritizes safety with multiple integrated features. It includes an overheating safety mechanism that preemptively shuts down the boiler to prevent damage, requiring a simple reset. Furthermore, it boasts an internal frost protection device that activates the pump and, if necessary, the burner, to safeguard the boiler from freezing when temperatures drop.
A critical safety aspect involves its condensate management. The boiler will cease operation if the condensate drain becomes blocked, which can happen during freezing conditions. Users are advised to unblock external pipes using warm cloths. For installation, careful routing of the condensate discharge pipe with a continuous fall is essential to prevent blockages and ensure proper function.
The Ecofit Pure 835 comes equipped with a speed-regulated high-efficiency pump. This intelligent pump automatically adjusts its output to the hydraulic conditions of the heating installation, optimizing energy consumption. Should a low loss header be installed, the pump's speed regulation can be fixed to a specific value for consistent performance.
Maintaining proper heating water quality is crucial for the boiler's longevity and efficiency. The manual stresses the importance of checking the pH value (ideally between 6.5 and 8.5) and the presence of sedimentary materials or magnetite. It also advises against unsuitable additives and recommends specific, approved cleaning agents and inhibitors to prevent corrosion, especially given aluminium components.
For installations, the boiler is suitable for timber frame buildings when installed according to IGE/UP/7. Its high-efficiency design means that compartment ventilation is generally not required, as heat loss from the casing is minimal. Various flue outlet configurations are possible, including horizontal and vertical concentric types (C13, C33, C43, C53), requiring specific clearances and, in some cases, a terminal protection kit.
The boiler’s operating concept includes an ‘installer level’ accessible to competent persons, offering detailed diagnostics and check programmes. These programmes facilitate tasks like purging the heating circuit, testing maximum and minimum load operations, and preparing the system for filling or draining, streamlining the commissioning and maintenance processes.
Setting the domestic hot water temperature is also managed through the interface, with a significant emphasis on Legionella prevention. The manual advises ensuring end-users are aware of anti-Legionella measures, noting that Legionella can multiply at temperatures below 60 °C. Additionally, if water hardness exceeds 3.57 mol/m³, the hot water temperature should not exceed 50 °C.
Regular inspection and maintenance are paramount for validating the warranty and ensuring safe, efficient operation. The manual provides a comprehensive list of annual checks, including verifying flue integrity, gas flow rates, CO² content, and the condition of various components. After servicing, the Benchmark Service Interval Record section must be completed by a competent person.
For convenience and ease of use, the unit features a Live Monitor that displays status codes, providing instant feedback on its current operating mode. This allows installers and service engineers to quickly ascertain the boiler’s state, whether it’s in heating mode, domestic hot water mode, or a temporary shutdown period, aiding in rapid troubleshooting.
Frequently Asked Questions (FAQs)
Can't find the answer you need? Here are some frequently asked questions about the Vaillant Ecofit Pure 835 Boiler, and we answer them below.










