DR-SG Front
Dorchester DR-SG 2

Available in 10 power outputs over 3 storage capacities

Features a full stainless steel tank, heat exchanger and coil offering a durable solution while maximising product life

5 year warranty
E ErP rating
BIM Objects icon
Suitable for commercial buildings
Part L Compliants

Product information

    • 10 output models in the range 20-210, 25-210, 30-210, 35-356, 50-356, 60-356, 70-538, 80-538, 80-538, 100-538, 120-538 
    • Storage tank, heat exchanger and coil all manufactured from stainless steel 
    • Enhanced durability under challenging water conditions 
    • ErP Class A
    • NOx under 40 mg/kWh across the range (Class 6) 
    • Fully Part L Compliant
    • 5 year warranty, as standard
    • Quick and easy burner access 
    • Operated via the popular Siemens LMS Mini controls platform
    • Integrated flue non-return valve 
    • Can deliver flow rates to satisfy high demand environments
    • Suitable for natural gas and LPG systems (conversion kit available)
    • Designed to fit through a standard 800mm doorway with a narrow diameter of <80cm (excluding 538 model)
    • Combustion chamber can be cleaned using water jets. Design of the bypass greatly minimises any risk of clogging
    • Optional accessories available for efficient system management, as well as enabling connection to wider BMS systems

Technical data

Units DR-SG 20-210
Max Heat Input (Gross) kW 20
Max Power Output (Net) kW 21
Building regulations Part L, EN89 100% efficiency (NCV) % 105
Building regulations Part L, EN89 100% efficiency (GCV) % 94.6
Standby Loss kWh/day 1.6
Building regulations Part L, Maintenance Consumption (EN89) kWh/day 2.7
ErP efficiency rating A
Water Heater Efficiency (ErP) % 95.9
ErP Load Profile XXL
Storage Capacity L 210
Continuous Flow at ΔT 30°C l/hr 600
1st 10 mins at ΔT 50°C l/10' 175
1st hour at ΔT 50°C l/60' 450
Continuous Flow at ΔT 50°C l/hr 360
Max DHW temperature setpoint °C 80
Max operating pressure (open vented) bar 7
Max operating pressure (unvented) bar 6.5
Cold Inlet connection Rp 1 1/2"
Hot outlet connection Rp 1 1/2"
Secondary return connection Rp 1 1/2"
Gas Inlet Pressure (Nominal, G20) mbar 20
Gas flow rate (G20) m³/hr 2.1
Gas Inlet Pressure (Nominal, G30) mbar 37
Gas flow rate (G31) m³/hr 0.8
Gas connection R 3/4"
Max flue gas temperature °C 100
Nominal flue gas operating temp °C 39
Flue Gas Volume @15°C kg/h 33.1
NOx emissions mg/kWh 29
Pressure at flue outlet Pa 110
Air inlet/Flue outlet diameter mm 80
Max system length - C type flues m 20
Fuse rating amp 6.3
Power consumption (maximum) W 12.7
Power consumption (standby) W 3.6
Electrical Supply V 230 V AC (+10%, -15%) 50Hz
Sounds Power Level (Noise emissions) dBA 64
Number of Anodes 1
Dry weight kg 96
Filled Weight kg 306
Height mm 1802
Diameter (inc insulation) mm 600


Dorchester DR-SG Brochure

Product brochures 2539 kb

DRSG flue starter kit installation manual

Installers guides 1659 kb

Dorchester DR-SG Installation Manual

Installers guides 11578 kb


Installers guides 5521 kb

Dorchester DR-SG - 20-30kW CAD

CAD 1463 kb

Dorchester DR-SG - 35-50-60kW CAD

CAD 1474 kb

Dorchester DR-SG - 70-80-100-120kW CAD

CAD 1459 kb

Dorchester DR-SG LPG - 70-80-100-120Kw CAD

CAD 1477 kb

Dorchester DR-SG Technical Submittal Sheets DR-SG 20-210 25-210 30-210

99 kb

Dorchester DR-SG Technical Submittal Sheets DR-SG 70-538 80-538 100-538 120-538

111 kb

dorchester DR-SG Technical Submittal Sheets DR-SG 35-356 50-356 60-356

103 kb

Ideal uses/applications

Often bought with

Burstock expansion vessel

Learn more

Halstock stainless steel calorifier

Learn more

Powerstock storage tank

Learn more