Electricity-based hot water cylinders are commonly used in many residential households in Australia. The two main types are resistive-element hot water (think: big kettle) and heat pump hot water (think: air conditioner technology).
“All Electric Household” Principle
In general, HEG™ advocates electricity-based hot water systems because they are an essential component of the “all electric household” principle, which is where all major appliances in a household are electricity-based, which then allows a renewable energy source (typically solar PV energy) to power the appliances, or stored for later use in a home energy battery.
“all major appliances in a household are electricity-based, which then allows a renewable energy source… to power the appliances”
Excess renewable energy is sold out to the grid, and the householder is paid a feed-in tariff, so the Energy Retailer effectively becomes a paper, or virtual, battery. When heating, cooling and cooking are also electricity-based, then greater and greater efficiencies can be attained, and the amount of daily utility charges for, say, gas connections are eliminated. With electricity-based appliances, such as reverse cycle air conditioners (also known as “Heat Pumps”) and heat pump hot water cylinders, the energy efficiency of the appliances are substantially better compared to traditional appliances (often 400%+ better!), so power costs are reduced, which allows the rooftop solar PV systems to offset a greater amount of the power bill.
HPHW systems use up to 80% less electricity
Hot water can account for 20% to 35% of a typical power bill, so it makes sense to try to minimise expenditure on heating hot water. A heat pump hot water cylinder is way cheaper to run than a traditional resistive-element hot water cylinder, using up to 80% less power for an equivalent hot water cylinder size. Reclaim Energy state that it typically uses $1 per day.
“The Reclaim Energy Heat Pump Hot Water system uses $1 per day to operate, typically”
Within different heat pump hot water system brands, they have a range of efficiency levels, often measured in such terms as C.O.P. (Coefficient of Performance) or E.E.R. (Energy Efficiency Ratio). In essence, the higher the numbers, the more efficient the hot water system. They rate the amount of power consumed to heat an amount of hot water… the less power required, the more efficient it is. The C.O.P. of a traditional electric element hot water cylinder is approx 1 (100%), whilst the C.O.P. of the best residential CO2-based heat pump hot water cylinders is 4 to 5.6 (up to 560%) efficiency rating.
The electricity consumed by a HPHW system is not used to directly heat the water. Instead, the electricity is used to operate fans, compressors and other mechanical processes, which is necessary to cause a change of state (liquid to gas, and vice versa) of a special compound called a refrigerant on a closed-loop, round-trip, high pressure journey from an air-sourced heat pump to the hot water cylinder.
This round-trip journey collects heat from the outside ambient air temperature^, which is then released into the water via a high surface area series of pipes in the tank.
^ Because the air temperature gains its heat from the sun originally, the heat pump hot water cylinder is technically classed as a solar hot water system. As such, the Australian Commonwealth Government applies tradeable renewable energy certificates (rebates!) to the installation of such a system, called Smallscale Technology Certificates. This offsets the cost of installation by $900 to $1100, depending on brand, size and location, and is offered as a point-of-sale discount by the installer, typically.
CO2, Greenhouse Gases & Climate Change
HEG™ recommends the Reclaim Energy Heat Pump Hot Water system, which uses a CO2-based refrigerant. Now, carbon dioxide, CO2, is a greenhouse gas, but it is a 1000 times better than most of the common refrigerants used in other HPHW’s and air conditioners, and leads to far better energy efficiencies, thus saving Greenhouse gas emissions caused by non-renewable electricity generation.
What does “Greenhouse Gas” mean? In a nutshell, when sunlight hits the earth, it is absorbed as energy by the physical mass of the earth, both water and land. Much of this energy is emitted into space in the form of infrared electromagnetic radiation at a lower frequency than the incoming sunlight. Greenhouse gases absorb much of the lower-frequency radiation energy, thus retaining it inside our atmosphere. In other words, sunlight can enter our atmosphere easier than it can escape.
“In other words, sunlight can enter our atmosphere easier than it can escape.”
This “containment” of the energy is amplifying the natural, cyclical weather patterns, effectively super-charging them. This leads to what is commonly called Climate Change, whereby the additional energy in the atmosphere increases the frequency, duration and ferocity of weather events. This includes both ends of the weather spectrum, including cold snaps, record average heat temperatures, droughts
Global Warming Potential (GWP)
CO2 is the benchmark for Global Warming Potential, and is given a GWP rating of “1”. If a refrigerant had a GWP of 10, for instance, then if one kilogram is released into the atmosphere it would have 10 times the harmful effect of one kilogram of carbon. Common refrigerants in the air conditioning and heat pump hot water industries have super high GWP ratings, such as:
- R410a = GWP of 2088. R410a is the standard for most heat pump hot water cylinders and the most abundant refrigerant for residential reverse cycle air conditioners (heat pump AC’s) over the past 10 years.
- R32 = GWP of 675. The new standard for reverse cycle air conditioners over the past 3 years, achieving higher levels of efficiency.
As you can imagine, whilst CO2 does contribute to Greenhouse Gases, it is in a closed loop, it is naturally occurring in our atmosphere, and is alternatives are up to 2000 times more harmful if released into the atmosphere.
It operates better in Tassie than NSW!
The Reclaim Energy HPHW system attracts a higher government rebate in Tasmania than in does in NSW, for instance. This is due to the ability of CO2 to operate at high working pressures, which means that greater differences between the source (air) and destination (water) temperatures allows a more efficient and effective transfer of heat. The more efficiently a hot water system operates, the greater amount of greenhouse gases are avoided (think: coal power), and thus a higher government rebate.
A bit about the Reclaim Energy HPHW System
The Reclaim Energy Heat Pump Hot Water (HPHW) System uses a CO2-based refrigerant, and so is even more efficient that a standard reverse cycle air conditioner (aka heat pump). Reclaim Energy HPHW is a split system, whereby the tank cylinder, controller and the compressor are separate.
Most HPHW systems as “all-in-one”, but a split system provides flexibility with the installation as the outside unit can be placed in an optimal position to ensure a good air flow, either ground, wall or roof-mounted.
The Reclaim Energy HPHW technology uses 1kW of energy to generate 5kW of heat or more, which translates to 80 percent less energy being required compared to traditional hot water cylinders of an equal size. The system attracts the equal highest level of government rebates of any currently available hot water heat pump.
The CO2 refrigerant and innovative design allows a rapid refresh rate, sop much so that it doesn’t even require a back-up element in cold weather. It also has fantastic warranties, such as 6-year compressor warranties, 7-year tank warranties and a 1-year controller warranty.
The heat pump and its tank can be located up to 10 metres apart horizontally, or 4 metres vertically, connected with pipes. The 315-litre glass-lined tank is fully insulated for minimal heat loss and has been mains pressure rated.