Hamworthy Varmax

Hamworthy Varmax View Large Image

Varmax boiler

The Varmax is a high output floor standing condensing boiler. A stainless steel fully welded heat exchanger makes it extremely tolerant to a wide range of system water conditions and gives it a long life.

With outputs ranging from 120kW to 637kW for single boilers, the Varmax boiler, featuring twin return connections, is ideally suited for split temperature systems and projects such as medium sized district heating schemes. Additional to 96% gross seasonal efficiency for cost-effectiveness, generous insulation assures standby losses are kept to a minimum.

New larger models added November 2020 - The range consists of 10 single boilers with outputs (at 50/30°C) of 127, 148, 191, 238, 290, 338, 415, 478, 558, 637kW. 

The high water capacity of the heat exchanger and being non-dependent on system flow allows operation with wide differential temperatures. This makes the Varmax not only efficient, but removes the need for a dedicated primary circuit, simplifying system design.

5:1 turndown of the premix burners allows accurate load-matching to supply only the heat that is required. Along with a NOx emission lower than 40mg/kWh, it far exceeds Energy Related Products Directive (ErP) criteria. A built-in flue gas non-return valve allows for easier flue system design whilst protecting from re-circulation of flue gases through non-firing boilers.

Comprehensive built in controls can manage multiple heating systems including domestic hot water cylinder and up to three independent heating circuits operating at different temperatures to one another. Multiple boiler control is possible without the need for an additional sequence control panel.

  • Durable corrosion resistant stainless steel heat exchanger backed up by 5-year heat exchanger warranty (T&Cs apply)
  • Tolerant to a wide range of water conditions
  • Up to 96% gross seasonal efficiency
  • Close load matching with 5:1 turndown ratio
  • Low environmental impact with NOx emissions <40mg/kWh
  • Ideal for medium sized district heating schemes and split temperature systems
  • Built in Siemens controls platform with sequence control for up to 16 boilers, multiple heating circuits and hot water circuit using the master/slave principle
  • Reversible control panel and quick release panels simplify service and maintenance
  • Natural gas or LPG


  • A large range of off the shelf flue options available 
  • Room sealed and open flue solutions
  • Flue header kits
  • Unvented kits 
  • Single and multiple boiler controls
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