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Calitec TechTalk: A refrigerant or a water cycling heat pump hot water system?

Updated: May 23

Peter Ras is Calitec's technical expert in heat pump hot water systems. In this TechTalk blog series, he delves into more technical subjects and topics related to heat pump hot water in New Zealand.


Calitec offers two types of heat pump hot water (split) systems: refrigerant cycle and water cycle. Both are designed for New Zealand’s environment and its coastal areas. But what sets these two systems apart? The key differences lie in their setup, installation requirements, and operational characteristics. Let's explore these aspects in more detail.



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Calitec TechTalk

 

Water cycling #1: How does it work?

A water cycle system has the heat exchanger built into the heat pump outdoor unit and cycles the water through the hot water cylinder by means of a circulation pump. The maximum pipe length between the heat pump unit and the cylinder depends on the insulation of these circulation pipes.


Our Calitec water cycle heat pump offers the option to heat and control two separate hot water cylinders, each at their own temperature setting. This feature could be useful for a separate en-suite hot water cylinder or an under-bench kitchen hot water cylinder.


Our system is intelligently controlled, providing a reliable hot water supply regardless of weather conditions or time of day, ultimately saving you more than 75% on your hot water costs. With a 5.8 kW heating capacity, our system surpasses standard electric heaters (which typically range from 2 to 2.4 kW), ensuring a much faster recovery time for your hot water cylinder(s) while consuming less power.


For added peace of mind, there is an emergency heating element of 3 kW built in the Calitec hot water cylinder, which you can switch on in case of a heat pump failure. Furthermore, we offer a 5-year warranty on the outdoor unit and a 20-year warranty on the hot water cylinder. For full warranty details, click here.


Refrigerant cycling #2: How does it work?

In a refrigerant cycle split system, the outdoor unit pumps its refrigerant through a coil (heat exchanger) inside the hot water cylinder, where the heat is released, and the water is heated. The maximum 20-metre refrigerant pipe length between the outdoor unit and hot water cylinder provides plenty of flexibility to place the outdoor unit out of sight.


Our system is an intelligently controlled set and forget system. It provides a reliable hot water supply in any weather and any time of the day, saving you up to 70% of your hot water costs. The 4 kW heating capacity is more than a standard electric heater (2 to 2.4 kW), ensuring a much faster recovery time for your hot water cylinder (as well as using less power). Our Duplex stainless steel hot water cylinders are insulated with Polyurethane Foam.


The Calitec System is designed and built using the highest quality parts and is designed to last at least 10-15 years. After this time, your outdoor unit may need replacing but there is no need to replace the whole system.


There is an emergency heating element of 3 kW built in which you can switch on in case of a heat pump failure. There is a 5-year warranty on the outdoor unit and 20-year warranty on the hot water cylinder. For full warranty details click here.


Heading #3: Pros and Cons of both systems

Water Cycle Systems:

How it works: The heat exchanger is built into the heat pump outdoor unit, and water is cycled through the hot water cylinder via a circulation pump.


Ideal for outside back-to-back installations but can also work well with distance split setups with well-insulated circulation pipes.


Can be installed by a plumber without the need for an additional heat pump installer.

Water circulation pipes must be insulated to minimize energy losses.


Pros:

  • Installation can be done by a plumber without the need for a heat pump installer.

  • Compatible with any heat pump-ready hot water cylinder, preferably Calitec's Duplex stainless steel cylinder.

  • Calitec's heat pump can control two separate hot water cylinders if desired.

  • Higher output power (5.8 kW) ensures a shorter recovery time for the hot water cylinder.

  • Uses R290 refrigerant, which has a GPW of only 3, making it environmentally friendly.


Cons:

• Water circulation pipes must be insulated.


Refrigerant Cycle System:

How it works: The refrigerant cycles from the heat pump outdoor unit through the refrigerant pipes to the hot water cylinder with the built-in heat exchanger, where heat is released to the water and then back to the outdoor unit.


Specifically useful for distance split system setups, such as upgrading or replacing an existing hot water cylinder.


Offers a lot of flexibility in placement, allowing the hot water cylinder to be located in the hot water cupboard or as close as possible to kitchen and shower taps.


Refrigerant pipes are easy to install under the house or in the attic space, depending on the house's layout. (compared to water circulation pipes)


Uses R32 refrigerant, which has a Global Warming Potential (GPW) of 875.


Pros:

  • Refrigerant pipe distance between outdoor unit and hot water cylinder can be up to 20 meters with minimal energy losses.

  • Outdoor unit can be placed out of sight due to the pipe lengths.

  • Hot water cylinder can be placed inside, close to kitchen and/or shower taps.


Cons:

  • Comes as a complete set purchase due to the built-in heat exchanger in the hot water cylinder.

  • Requires a heat pump installer for installation of the refrigerant part.


Designed for New Zealand's environment

Both of Calitec's heat pump hot water systems are designed with New Zealand’s environment in mind. The materials and components used are chosen for their durability and resistance to corrosion, ensuring longevity and performance, even in coastal climates. By tailoring our systems to local conditions, Calitec ensures that customers receive the most efficient and reliable hot water solutions available.

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