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Benefits of Installing a Heat Pump Hot Water Cylinder: Is It Worth It?

In today’s world, we’re all looking for ways to save energy and reduce our bills. One way to do this is by installing a heat pump hot water cylinder. Heat pumps are energy-efficient devices that take energy from the air and use it to heat water. This process is much more efficient than traditional gas or electric systems and can save you a considerable amount of money in the long run. But is it really worth the initial cost and effort of installing a heat pump hot water cylinder? In this article, we’ll explore the benefits of installing a heat pump hot water cylinder to help you decide if it’s worth it for you.

What is a Heat Pump Hot Water Cylinder?

A heat pump hot water cylinder is a device that transfers the heat from your home’s air into your hot water system to reduce your energy usage. It works much the same way as a refrigerator, except that it uses the outside air as the cooling source instead of refrigerant. A heat pump hot water cylinder can be installed in the electric system, provided it’s of a high enough capacity. Heat pumps can save you a lot of money on your energy bills compared to traditional systems, but they do require an initial investment. Heat pumps take advantage of the “thermal gradient”, which is the difference in temperature between the inside and outside of a building. The smaller the difference, the more efficient the system will be. During the summer, the thermal gradient is reduced and the heat pump becomes much more efficient. Some heat pumps during the winter months are less efficient since the outside temperature is usually much lower at that time of year.  However, you can combat this by installing a heat pump that can provide good efficiencies down to -15 degrees.

Benefits of Installing a Heat Pump Hot Water Cylinder

There are many benefits to installing a heat pump hot water cylinder, including lower energy bills, reduced carbon emissions, and a more efficient system overall. A heat pump hot water cylinder such as this Rheem can save you hundreds of dollars per year in energy costs. Depending on the size of your home and the size of the cylinder installed, the savings can be even higher. Heat pumps are also environmentally friendly, as they reduce your carbon emissions by as much as 40% compared to a traditional system. A heat pump hot water cylinder can last for years, so you don’t have to worry about it breaking down and needing to be replaced any time soon as long as regular maintenance is taken (every 3-5 years). A heat pump hot water cylinder can lower your risk of water damage and water loss due to the increased efficiency of your system. If a heat pump hot water cylinder malfunctions, you can usually detect it and have it replaced without incurring any significant costs.

Cost Savings

Depending on where you live and your current energy costs, the initial investment in a heat pump hot water cylinder can be anywhere from $5,000 to $9,000. However, it can pay for itself in as little as five years if you’re in an area with high energy costs. The savings you’ll get from a heat pump hot water cylinder are due to the lower energy use and the fact that you don’t have to replace it as often. Your energy costs will be lower because heat pumps use less energy to heat your water than a standard system. This is due to the fact that the air outside your home is naturally cooler than the air inside your home. When you use a heat pump hot water cylinder to heat your water, the system uses that outside air as a heat source. This is much more efficient than using an electric or gas heating system, which transfers the heat from one area to another. A heat pump hot water cylinder will also last longer than a traditional system, meaning you don’t have to replace it as often. This will save you additional money in the long run.

Environmentally Friendly

Heat pumps are environmentally friendly due to the fact that they use outside air as a source of heat instead of transferring heat from one place to another as standard systems do. This means that there will be less heat loss, resulting in a more efficient system that requires less energy than traditional systems. This reduced energy use means that your carbon emissions will be reduced by as much as 40% when you use a heat pump hot water cylinder compared to a traditional system. Heat pumps will also last longer than traditional systems (with servicing), reducing the number of carbon emissions that are released due to the need to replace the system.

Potential Drawbacks

One of the drawbacks to installing a heat pump hot water cylinder is that it requires an extra electrical circuit. This means that you will either have to install a new circuit or add an additional circuit to your electrical system. The cost of adding an electrical circuit is usually not significant, particularly when compared with the amount of money you can save over a period of years due to the lower energy use. However, if your home doesn’t have enough electrical capacity for a new circuit, you may need to run an extension cable to the nearest circuit. The cost of this will depend on the length of the cable and the type of cable you use. Additionally a heat pump can be noisier than traditional hot water cylinders although modern technologies and being external often negate much of this issue. A heat pump hot water cylinder is also more complex than a traditional system, so you may need to hire a professional with the right credentials to install it for you. While a heat pump hot water cylinder is more efficient than a traditional system, the initial investment is usually more than when installing a traditional system.


Overall, a heat pump hot water cylinder is a great way to save money on your energy bills and reduce your carbon emissions. The initial investment may be more than a traditional system, but it will pay for itself in no time. The benefits of installing a heat pump hot water cylinder outweigh the drawbacks, making it a worthwhile investment for most homeowners. If you’re looking to lower your energy costs, a heat pump hot water cylinder is a great option. With the reduced carbon emissions and increased efficiency, it’s no wonder that heat pumps are becoming more and more popular. Give Hot Water Cylinders NZ a call today and see how much money on hot water you could save long-term!

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Product Review: Rinnai Hotflo Hot Water Heat Pump

Have you considered heating your water with a heat pump? Heat pump water heaters are becoming increasingly popular with home owners looking for more efficient methods of water heating.

How do they work and what are the benefits?
Heat pump water heaters work like fridges in reverse, using electricity to move heat from one place to another instead of generating the heat. They can be up to three times for efficient than a conventional electric hot water cylinder. To move the heat, heat pump water heaters pull heat from the surrounding air and dump it at higher temperature into a tank to heat the water.


The Rinnai Hotflo Hot Water Heat Pump was designed for homeowners who want to significantly reduce running costs while minimising their carbon footprint. Rinnai state that the Hotflo heat pumps offer an energy consumption profile similar to solar water heating systems and can generate up to 700 liters of hot water per day. Under normal operating conditions, the Hotflo will will around 66% electricity than a typical electric hot water cylinder.

Key benefits and features:

  • Retrofits to virtually any brand of electric hot water cylinder
  • Simple installation, usually takes less than one day
  • Carbon footprint reduction with reduced energy consumption


Rated input 1.9 kW
Max. energy output 6.0 kW
This is the maximum possible from the unit and should be used to ensure the tank TPR valve is suitably sized.
Max. water pressure 850 kPa
Refrigerant type/mass R134A/750 g
Refrigerant pressure High 2.7 MPa, Low 1.0 MPa
Refrigerant compressor oil Type: Neo 32, quantity: 520 ml
Ingress protection IP24
Noise level Fan approx. 55 dB(A)
Net weight 60 kg
Power supply 240 V, 50 Hz

Ambient temperature operating range
Operating temperature range is -7 to 45 °C. When the ambient temperature is below 2 °C the tank temperature achieved may be lower. When the ambient temperature is high, the air supply fan will run at a lower speed.

Start up protection
When the power is first turned on to the heat pump, or when the power is cut, then retsored, the unit will not start for three minutes. This is to protect the condenser.

Defrosting function
The heat pump has protection systems that will stop the operation of the unit if; the air inlet/outlet is blocked, voltage is out of nominal range (207-255 V), over pressure, or over temperature in the refrigerant system.


Despite being very efficient, the best heat pump units will be more costly than an electric water heater and are more likely to have failures than electric water heaters. Installation will also be trickier, as they need a supply of warm air to be able to run effectively. This can be a disadvantage during the winter and in colder places.

Indoor Installation
Installation indoors could be challenging due to how these heat pump systems work. Because the heat pump uses the air around it, and exhausts cold air, it will be increasing more difficult for it to extract heat from the same cold air it has extracted. This wastes power and extends the running time of the heat pump, making it less efficient. If using a split system, you will want to heat pump installed outside and the tank inside, which will work well.

Repair Costs
It is common to be facing repairs soon into the life of a heat pump system, usually once the warranty has expired.

Heat pumps do make a humming sound similar to an air conditioner while operating. This could cause disruption depending on placement and how sensitive to sound the occupants of the house are, so this should be taken into account when deciding where to install the unit.


Heat pump water heaters are a good option for high hot water users who want to improve the efficiency and performance of their water heating system. They provide a fast ROI, being up to three times more efficient than electric water heating systems. The Rinnai Hotflo Hot Water Heat Pump is a top of the range choice if you want to go the heat pump route, providing you with efficient water heating and hot water on standby.

For more information on the Rinnai Hotflo Heat Pump, download this PDF.
pdfRinnai Hotflo Heat Pump Water Heater PDF

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What are Calorifiers?

A calorifier is a heat exchanger which heats water indirectly by circulating it over a heating coil or multiple coils. The source of heat can be water or steam, heated by an external heat source, contained within a pipe immersed in the water. the two bodies of water or steam do not mix. (touch each other)

In hospitals and factories where steam is already being generated for other uses it can also be used to heat the water by the indirect method.

The calorifier may be a continuous coil of pipe or a cylinder within a cylinder with an annular space between the two vessels.


With the vertical hot water cylinder, the steam enters the coil though the top connection. the strainer or grit trap removes any solid matter suspended in the steam. The steam then passes through the inlet valve which is thermostatically controlled. the thermostat prevents overheating or boiling of the stored water.

A steam trap, fitted near the outlet of the coil, prevents the steam from leaving the coil until it condenses.

In a hot water cylinder which contains a steam coil, the coil must be able to be removed for descaling. this is more likely to occur using steam because the coil is working at a higher temperature than with the conventional hot water system.

Hot water cylinders Ltd provide custom hot water cylinder (storage tanks) design and construction with integrated calorifiers at most demanded KW sizes. Our services include domestic and commercial applications. With water applications heat sources such as Heatpumps, Gas, Solar or steam can be applied. For more information please contact us on 0800 4 CYLINDERS.