The R3600 series of gas-fired condensing boilers from ELCO set bench marks for high output, combined with low weight, compact dimensions and low emissions. Up to 1043kW is obtainable from a single unit.

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MHS 10 year Guarantee
  • Compact dimensions and light weight
  • Modulation ratio 3.5:1
  • Low water content
  • Option for room sealed flue
  • Up to 8 boilers in cascade
  • Working pressure 6bar
  • 2 year guarantee – 1st year’s service included
Boiler Model R3600SB
Nominal heat output 80/60°CkW142.7-572
Nominal heat output 50/30°CkW150-601
Nominal heat input (gross)kW162-649.3
Nominal heat input (net)kW146-585
Approx flue gas volume max @ max loadm 3 /hr969
NOx level @ 0% O 2 @ max loadmg/kWh32.3
Boiler Model R3601SBR3602SBR3603SBR3604SBR3605SB
Nominal heat output 80/60°CkW183-639213.1-747241.5-846270-945298.4-1043
Nominal heat output 50/30°CkW192.1-671223.7-784253.5-888283.4-992313.2-1095
Nominal heat input (gross)kW207.5-724.8241.9-848274.1-960.1306.3-1072.2338.5-1183.2
Nominal heat input (net)kW187-653218-764247-865276-966305-1066
Weight empty/fullkW890/9801040/11371150/12541280/13901410/1527
Boiler seasonal efficiency* (gross)%95.8495.8495.8495.8495.84
NOx emission @ 0% O 2mg/kWh11.511.511.511.511.5

*Calculated using the formula given in Equation 2 in the Non-Domestic Building Services Compliance Guide


Four R3604 boilers have been installed at Watermark Place, a fourteen floor, 42,350m2 commercial office development. The building also creates one of the large public realms north of the Thames in the City of London. 

Construction of the landmark city building is still underway. When completed it is expected to notch up an ‘excellent’ BREEAM environmental rating aided by the latest environmentally and energy efficient MHS Ultramax R3600 series condensing boilers.

The energy efficient Ultramax boilers will serve the building’s main fan coil units, underfloor heating, radiators, perimeter heating and air handling units.

Specifier Mark Terndrup of Waterman Building Services commented:  “Their low NOx emissions were vital in the choice of R3604 units for Watermark Place. Low NOx emissions will be an important contributory factor in the building achieving an excellent BREEAM environmental rating.”

Mr Tendrup added: “We have a long standing relationship with ELCO (formerly MHS Boilers) based on the ability of their products to meet both the technical requirements and economic conditions specified in our high value contracts.”

R3600 SB appliances offer important space saving and low weight loading. With output to floor space of around 380kW/m² and power to weight nominally at 0.98kW/kg; compared with a similar output conventional shell and tube boiler which is more than twice the weight and approximately 14 kW lower output per square metre of footprint (not including the space needed for the burner).

Commenting on space saving achieved Gary Edgar, Projects Director N G Bailey said:  “The compact arrangement of the boilers was the best solution due to co-ordination restrictions within the basement boiler house.”