Halstock calorifier
Halstock stainless steel calorifier
Halstock stainless steel calorifier

Stainless steel calorifiers for indirect hot water.

5 unvented calorifier models and 4 open-vented calorifiers available with continuous outputs (@44°C ∆T) of 390, 527 and 1055 l/h.

Warranty 5 cylinder product item
ErP Part L Compliant product icon

Product information

    • Power outputs 20-54kW and storage capacities 305-965 litres.
    • Indirect method of producing safe and hygienic domestic hot water  (want to understand the difference between Indirect vs Direct Hot Water Systems?)
    • Hot water cylinder and coil made out of corrosion resistant stainless steel.
    • Long life backed up by a 5 year cylinder warranty.
    • Minimal heat loss for maximum economy thanks to layer of CFC-free polyurethane tank insulation under protective plastisol cladding.
    • Highly efficient heat transfer from a corrugated coil design.
    • Low maintenance as no sacrificial anodes or powered corrosion protection systems needed.
    • Can be located wherever convenient.
    • Versatility in use – coupled to Hamworthy commercial boilers or direct heating/backup via immersion heater.
    • UK manufactured hot water calorifiers.
    • Compliant with Energy Labelling requirements of ErP.

Technical data

Units HS305
Capacity, nominal litres 305
Capacity with coil litres 298
Continuous output* @44°C ΔT l/h 390
Continuous output* @50°C ΔT l/h 344
Maximum working pressure, tank bar 6
Hydraulic test pressure bar 9
Coil output kW 20
Heat up time @50°C ΔT, coil only min 54
Recovery time (70% volume), coil only min 38
10 min peak output @50°C ΔT litres 361
Coil max operating temperature °C 100
Coil max operating pressure bar 3
Coil tube diameter DN DN20
Coil surface area m2 0.75
Standby losses @65°C kW/24hr 2.5
ErP efficiency rating - C
Immersion heater option, power kW 3
Immersion heater option, phase ph 1ph
Heat up time, Immersion only hour 5.8
Recovery time, Immersion only hour 4.1
Expansion vessel size litres 24
Weight empty kg 60
Weight full kg 354


Halstock calorifier brochure

Product brochures 820 kb

Halstock calorifier technical data

Data tables 554 kb

Halstock calorifier installation manual

Installers guides 3449 kb

Ideal uses/applications

  • To provide domestic hot water for any type of commercial building.
  • Designed for use with natural gas, LPG or oil-fired commercial boilers for primary heat source.
  • Direct heating via optional Incoloy 800 electrical immersion heaters.
  • Suited to all areas of the UK, particularly locations with soft water (read here why).

Optional extras

  • Electric immersion heater kits.
  • Choose from a wide range of service contracts to help maintain optimum performance.
  • Book commissioning with Hamworthy approved service engineers.

Often bought with

Stratton mk2 wall hung boiler

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Wessex ModuMax mk3 boiler

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Case studies

Riverside Children's Centre benefits from built-in boiler controls of their boiler to provide hot water efficiently.

Riverside Childrens Centre, Canterbury

Sector: Education and childcare

Project: The nursery provides childcare and cooked midday meals for children. A hot water priority strategy using built-in boiler controls made the combination of a hot water circuit with a low temperature underfloor heating circuit possible.

Building: Nursery refurbishment

Application: Space heating, 43kW, indirect fired DHW

Learn more