What Does Our Engineering Team do?

Find out exactly what our engineering team do here at Hot Water Heat Pumps.

Reducing the energy consumption and carbon footprint are important measures to address climate change. Hot Water Heat Pumps Ltd has been working for 40 years to develop one of the most efficient heating and cooling technologies in the world. Currently, most units and systems, designed by our professional engineering team, are in the higher range of efficiency up to 600% (a COP up to 6).

Our refrigerant based systems, instead of producing the heat, transfers heat from air/water to the desired fluid (air/water). Most of the energy is transferred over the refrigerant phase changes when refrigerant passes through the evaporator and condenser. HWHP Ltd. Is capable of designing and developing eco-friendly and efficient heat pump systems for water heating and more.

  • Pool and Spa Heating (Residential/Commercial)
  • Under Floor Heating Systems (Residential/Commercial)
  • Domestic Hot Water (Residential/Commercial)
  • Air Heating (Commercial/Industrial)
  • Designing Chillers for commercial and industrial applications
  • Designing Dehumidifiers for commercial, Industrial and Agriculture applications including greenhouses.
  • Engineering, installation and commissioning of indoor pool heating, air ventilation and condensation control systems (Residential/Commercial).
  • Designing the air distribution systems using fabric ducts (Commercial/Industrial)
  • R&D
  • Consultancy Services
  • PLC Programming

Our Heat Pumps

HWHP has the manufacturing capability to produce heat pumps for water heating in a variety of Residential, Commercial and Industrial applications.

Our 7GP and THP units are designed for primary heating of swimming pools up to 28˚C and spa water to 40˚C. They come in a range of sizes to offer economic water heating for both residential and commercial systems and can be installed new or retrofitted into most existing systems. We can also aid in sizing heat pumps for the operating environment and advise on the latent and sensible heat loads to be encountered with both swimming pools and spas. These units can also be supplied as heat/chill units, making them suitable for industrial applications such as plunge pools, Aquaculture and Hydroponic systems.

Our 7GU and 7GUb units are designed for use on underfloor heating water circuits with the ability to provide water temperatures of up to 40˚C to heat rooms via radiation and natural convection. 7GU units are designed to work with automatic zone control systems where rooms have individual climate control. For other systems, the 7GUb units are available with an onboard water pump and buffer tank. Both types are suitable for residential and commercial hydronic floor heating systems which do not have the temperature variations and draughts associated with other forms of heating. They are also designed for thermostat control. HWHP can also assist in sizing the correct heat pump based on the floor area and heat losses from the rooms.

Our 7GD and 7GDE units provide 60˚C hot water for potable use and in some industrial applications. To provide the best results, HWHP also provides advice on hot water storage systems including hot water cylinder design and sourcing. The 7GDE units operate with our patented single-pass water heating system which allows for easy retrofitting to most existing hot water storage systems and provides instantly available hot water to the top of the cylinder.

All the above units are capable of reducing energy consumption and reducing the carbon footprint when assessed against other forms of heating.

Our Chillers

HWHP also provide water chilling solutions with the 7GPC range. The standard range is designed for water chilling applications from 40˚C down to 10˚C making it suitable for use in Aquaculture and Hydroponic systems. There is also the 7GPCL range, which can be engineered for chilling down to -5˚C when using glycol solution as the medium.

HWHP can specify the correct Chiller for use on a variety of systems with experience in not only the Aquaculture and Hydroponics sector, but also for process engineering, plunge pools and for cooling machinery such as injection moulds, machine tools and lasers.

Our standard Chillers range in size from 7 to 140 kW depending on the required water temperature so there is a model for most small, medium, and large-scale industries. In addition, we can work on custom builds to suit the client’s requests based on whether it is an existing chiller system or a new build.

Units can also be designed to run as heat/chill units for keeping water at a constant temperature, allowing you to have more options for temperature control.


Our heat pump technology can be used for more than just heating water. The same technology can be used for commercial dehumidifiers to control the humidity in greenhouses and other controlled agricultural and industrial environments. With many agricultural diseases and other issues stemming from a high level of humidity, a greenhouse dehumidification system is a great way to maintain the ideal humidity levels in your greenhouse and improve plant performance.

Moisture forms on the surfaces of plant leaves when the temperature of the leaf drops below the dew-point temperature of the greenhouse environment. One method to prevent the formation of moisture is to decrease the dew-point temperature of the greenhouse. This is done by reducing the relative humidity of the air. Lower relative humidity levels result in the plant surfaces and greenhouse structure staying above the dew-point temperature, and preventing the formation of condensation. Dryer plants also absorb more nutrition aiding growth and crop yield. Our engineering team specialise in designing custom heat pumps and dehumidifiers to meet any requirements.

Dehumidification is also useful for industrial applications. This can include areas such as food processing, where it can reduce mould and spoilage.

“Engineering, installation and commissioning of the indoor pool heating, air ventilation and condensation control system is one of the most important aspects”


Having a healthy environment is one of the most important aspects when designing any indoor pool enclosure. A higher humidity rate will cause condensation to form, mould to grow and potential health issues. While these effects can be reduced by lowering the relative humidity, this will increase the evaporation rate from the pool surface and as a result, increase the water demand and energy cost. Condensation will form on the surfaces when the surface temperature is below the air dew point. The dew point is the temperature that the vapour in the air becomes saturated and condensation starts to form. Our indoor pool specific design will maintain the enclosure temperature at the set point, ventilate the air to keep the Relative Humidity in the acceptable range to reduce evaporation and increase comfort, and also control the condensation by keeping the surface temperature above the dew point. Our Indoor pool specialist team will use their knowledge and experience to provide the best solution for your unique project focusing on the following:


Energy Efficiency, Energy Recovery, Low carbon footprint

Our full range of indoor pool heating and ventilation design consists of:

  • Load Calculations
  • Duct and pipe sizing
  • Equipment selection
  • Preparing Engineering documents
  • Design Review
  • Vent Air Units/Air Handler Units on Site
  • Buffer Tank system with pipe work

Designing air distribution systems using fabric ducting

HWHP Ltd has found that fabric ducting is best suited from a technical, cost and installation point of view for providing more even air distribution through a room. Our engineering team design the fabric duct systems based on the customer’s specific requirements. Some of the common advantages of fabric duct when compared with steel ducts are:

  • Lower capital cost
  • Fast installation
  • Light Weight
  • Wide range of shapes
  • Customized air distribution
  • Condensation free
  • Low noise level
  • No requirement for seismic restraining
  • Lower maintenance and cleaning costs
  • Lower transportation costs

PLC Programming

All our products have the option to be fitted with our advanced control system that utilises PLC programming to provide accurate control and connectivity to a range of networks from commercial BMS to a residential home network. The control system can provide remote access to monitor and change the heat pump parameters, energy usage and performance monitoring, simplify fault-finding, and manufacturer access to diagnose and solve any potential issues.

All our control systems are programmed in-house by our team of engineers and can be customised to suit any requirements. The flexibility provided by our Carel c.pCO PLC Controllers means that we can provide PLC controls as a standalone solution to meet your control needs. Whether you require BMS integration on an existing heat pump installation or remote monitoring of your HVAC plant, we can provide a custom control solution and bring your equipment into the 21st century.

Testing of Third-Party Heat Pumps

With 40 years of experience in water heating and cooling with heat pumps, HWHP Ltd can offer our services for testing heat pumps from other manufacturers to provide a performance report for a variety of heat pumps. Our test room allows for a variety of environmental conditions to be replicated to ensure that units are suitable for New Zealand conditions. A survey of the heat pumps assembly, components and programming can also be provided with the performance data to provide recommendations to the end user. This will allow the customer to make the right choice when selecting a heat pump for their needs.