Room sealed fully automatic direct fired atmospheric water heater for domestic hot water.

5 models available with continuous outputs (@44°C ∆T) of 507, 811, 1293, 1740, 1960 l/h.

Due to the Energy-related Products (ErP) Directive regulations we have a limited stock available of atmospheric water heaters. Talk to us today to secure your product or find out about availability.

Fuel NG LPG product icon
Efficiency 82 product icon
Warranty 2 product item
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  • Power outputs 25-100kW and storage capacities of 265-324 litres.
  • Simple and safe domestic hot water generation.
  • Ideal for ventilation limited rooms.
  • Reliable hot water when you need it.
  • Can be installed close to the point of use.
  • Natural gas and lpg water heater options.
  • Easy access for service and maintenance.
  • 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.

Due to the Energy-related Products (ErP) Directive regulations we have a limited stock available of atmospheric water heaters. Talk to us today to secure your product or find out about availability.

Specification Units Dorchester DR-RS Model  
DR-RS 25 DR-RS 40 DR-RS 65 DR-RS 85 DR-RS 105
Water Continuous output with 44°C ΔT l/h 507 811 1293 1740 1960
Continuous output with 50°C ΔT l/h 446 714 1138 1531 1725
Continuous output with 55°C ΔT l/h 406 649 1034 1392 1568
Storage capacity litres 324 312 265 265 265
Maximum operating water pressure (open vented) bar 8 8 8 8 8
Maximum operating water pressure (unvented) bar 3.5 (=cold feed pressure reducing valve preset in unvented kit
option)
Expansion relief valve setting (open vented kit) bar 5 5 5 5 5
Energy Building Regulations thermal efficiency gross % 82.31 81.11 81.15 80.15 80.20
Heating-up time, ΔT = 44°C min. 38 23 12 9 8
Heating-up time, ΔT = 50°C min. 43 26 14 10 9
Heating-up time, ΔT = 55°C min. 47 28 15 11 10
Standby losses kW/24h 9 10.4 8.3 9.0 9.9
Gas Nat. Gas
G20-20mbar
Input power, gross-maximum kW 31.6 51.2 81.6 111.1 125.2
Output power-maximum kW 25.9 41.5 66.2 89.0 100.3
Gas inlet pressure-nominal mbar 20 20 20 20 20
Gas flow rate-maximum@1013.25 mbar and 15°C m3/h 3.1 5.0 7.9 10.8 12.2
LPG
G31-37mbar
Input power, gross/ (net)-maximum kW 29.9 47.0 75.7 108.7 n/a
Output-maximum kW 25.0 38.9 62.6 89.0 n/a
Gas inlet pressure-nominal mbar 37 37 37 37 n/a
Gas flow rate-maximum@1013.25 mbar and 15°C kg/h 2.2 3.4 5.5 7.9 n/a
Flue Approximate flue gas volume @15°C, 9.8% CO2,
N.T.P. (nat. Gas-G20)
m3/h 39.3 63.4 100.2 137.0 154.8
Flue gas temperature-maximum °C 130 150 145 180 185
General Power consumption-DR-SE (DR-SA) W 100 100 100 275 300
Electrical supply Vac 230V 1Ph 50Hz  
Weight when empty kg 230 245 295 320 320
Approximate shipping weight kg 235 250 300 325 325
Maximum floor load/weight filled with water kg 554 557 560 585 585
 
  Title Type Size  
Dorchester DR-RS water heater brochure Dorchester DR-RS water heater brochure Product brochures 1552 ko Download
Dorchester DR-RS water heater dimensions Dorchester DR-RS water heater dimensions Dimensions 157 ko Download
Dorchester DR-RS water heater technical data table Dorchester DR-RS water heater technical data table Data tables 53 ko Download
Dorchester DR-RS installation manual Dorchester DR-RS installation manual Installers guides 2497 ko Download
Dorchester DR-RS 105 front view Dorchester DR-RS 105 front view CAD 13 ko Download
Dorchester DR-RS 105 plan view Dorchester DR-RS 105 plan view CAD 11 ko Download
Dorchester DR-RS 105 side view Dorchester DR-RS 105 side view CAD 14 ko Download
Dorchester DR-RS 25 front view Dorchester DR-RS 25 front view CAD 14 ko Download
Dorchester DR-RS 25 plan view Dorchester DR-RS 25 plan view CAD 11 ko Download
Dorchester DR-RS 25 side view Dorchester DR-RS 25 side view CAD 14 ko Download
Dorchester DR-RS 40 front view Dorchester DR-RS 40 front view CAD 13 ko Download
Dorchester DR-RS 40 plan view Dorchester DR-RS 40 plan view CAD 14 ko Download
Dorchester DR-RS 40 side view Dorchester DR-RS 40 side view CAD 14 ko Download
Dorchester DR-RS 65 front view Dorchester DR-RS 65 front view CAD 14 ko Download
Dorchester DR-RS 65 plan view Dorchester DR-RS 65 plan view CAD 11 ko Download
Dorchester DR-RS 65 side view Dorchester DR-RS 65 side view CAD 14 ko Download
Dorchester DR-RS 85 plan view Dorchester DR-RS 85 plan view CAD 11 ko Download
Dorchester DR-RS 85 side view Dorchester DR-RS 85 side view CAD 14 ko Download
Dorchester DR-RS water heater wiring diagram Dorchester DR-RS water heater wiring diagram Wiring diagrams 153 ko Download
Dorchester DR-RS thermal efficiency sheet Dorchester DR-RS thermal efficiency sheet Seasonal efficiency sheets 85 ko Download
  • Smaller commercial and public buildings including community schools, care homes, hotels, churches and retail units.
  • Locations with no plant room or minimum ventilation.
  • Unvented water supply kit - essential for any unvented application and includes an expansion vessel sized for the water heater and local pipework only.
  • Top to bottom pump recirculation pump kit to prevent stratification and protect against legionella within the water heater.
  • Electrical anode protection.
  • Flexible replacement anodes.
  • 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.