Dorchester DR-LL atmospheric water heater
Dorchester DR-LL atmospheric water heater

Atmospheric direct fired low NOx water heater for domestic hot water.

3 models available with continuous outputs (@44°C ∆T) of 970, 1,300 and 1,800.

Warranty 2 product item
Fuel NG product icon
Efficiency 82 product icon
ErP Part L Compliant product icon

Product information

    • Power outputs 49-84kW
    • Storage capacities of 291 - 347 litres
    • Continuous outputs (@44°C ∆T) of 970 - 1,800
    • Easy fit replacement atmospheric water heater reduces installation costs
    • Install with most existing atmospheric flue designs (Subject to survey. New draught diverter must be fitted)
    • Fits into restricted height plant rooms thanks to a choice of optional draught diverters (angled or round)
    • Low NOx levels between 31-45mg/kWh makes it compliant with the stricter rules of the ErP legislation
    • Meets the needs of premises with large hot water demands
    • Easy to use LCD screen for simple operation, control and fault diagnostics.
    • Components are easily accessed for maintenance and servicing
    • Comes with magnesium anodes as standard for protection against corrosion
    • Suitable for unvented water systems using optional kit
    • Full project assistance with hot water sizing and selection of equipment to match the application
    • Extensive back up and support from our team of experienced engineers across the UK
    • Long-term commitment to spare parts
    • Available for next day delivery (dependent on stock availability, charges apply, order cut-off 12pm)


    Ask us about this atmospheric water heater, ideal for the replacement market. 

Technical data

Units DR-LL 50 -288
Continuous output with 44°C ΔT l/h 970
1st hour output with 44°C ΔT l 1400
Continuous output with 50°C ΔT l/h 850
1st hour output with 50°C ΔT l 1200
Continuous output with 55°C ΔT l/h 770
1st hour output with 55°C ΔT l 1100
Storage capacity l 291
Maximum working pressure bar 8
Load profile - XXL
Water Heating energy efficiency % 66
Net combustion efficiency (gross) % 91 (82)
ErP efficiency rating - B
Heating-up time, ΔT = 44°C min. 18
Heating-up time, ΔT = 50°C min. 21
Heating-up time, ΔT = 55°C min. 23
Nat Gas
Input, gross kW 60.0
Input, net kW 54.0
Output – maximum kW 49.1
Gas inlet pressure – nominal mbar 20
Gas flow rate – maximum @1013.25 mbar and 15°C m3/h 5.7
Mass flow rate flue gases (round draught diverter)* kg/h 161
Mass flow rate flue gases (draught diverter type 1)* kg/h 126
Mass flow rate flue gases (draught diverter type 2 - standard)* kg/h 118
Flue gas temperature (round draught diverter)* °C 161
Flue gas temperature (draught diverter type 1)* °C 126
Flue gas temperature (draught diverter type 2 - standard)* °C 133
NOx emission, dry air free, European Class 6. Maximum (at part load) mg/kWh 45
Power consumption (Nominal) W 65
Electrical supply Vac 230V 1PH 50Hz
Voltage tolerance % of Vac (-15+10%)
Sound level dB 64
Number of magnesium anodes - 4
Weight when empty kg 252
Approximate shipping weight kg 282
Maximum floor load/ weight filled with water kg 540
*Based on 1013.25 mbar and 15°C.


Dorchester DR-LL water heater brochure

Product brochures 3349 kb

Dorchester DR-LL water heater installation, commissioning and operating manual

Installers guides 8070 kb

Ideal uses/applications

Easy fit replacement for refurbishment projects - replaces our Dorchester DR-LA and DR-LP water heaters

Large and medium sized commercial and public buildings including schools, hospitals, offices and hotels

Locations with substantial and continuous hot water demands including hospitals, hotels and sports facilities.

Optional extras

Unvented water supply kit - essential for any unvented application; includes an expansion vessel sized for the water heater and local pipework only.

Flexible replacement anodes

Optional draught diverters with flue take-off: 45° angled or round vertical for ease of integrating with existing atmospheric flues. Please specify when ordering.

Choose from a wide range of service contracts to help maintain optimum performance.

Book commissioning at the same time as placing your order for improved warranty terms.

Flues available through our flue partner Jeremias UK.

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