What is a LPG hot water system?

A liquefied petroleum gas (LPG) hot water system is a water heater that uses gas to heat water. There are different types of LPG hot water systems. Storage tank models store the water at a set temperature until it is needed. Meanwhile, instant hot water systems heat the water to provide immediate and constant hot water.

Ensuring you have the best LPG hot water system is important for two key reasons. Firstly, hot water tends to consume about one-quarter of a household’s energy budget. Secondly, a more efficient LPG hot water system can help to reduce a home’s carbon footprint.

What is LPG?

Liquefied petroleum gas is either propane, butane or a mixture of both gases. Most importantly, when put under low-pressure compression, LPG will change from a gas to a liquid. This makes it easy to transport. It typically comes in cylinder containers or larger tanks.

What is the ideal gas for a sustainable hot water system?

Natural gas

The alternative to LPG in a gas-powered hot water system is to use natural gas. This requires a connection to the national gas network. Natural gas is a less sustainable option than LPG because it is worse for the environment. 

Natural gas is a fossil fuel, like coal or oil. Burning it releases carbon dioxide (CO2) into the atmosphere. Even worse, natural gas consists primarily of methane. This is a more potent greenhouse gas than CO2 over the short term. It traps 86 times as much heat in the Earth’s atmosphere over a 20 year period. 


On the other hand, LPG is not considered to be a greenhouse gas in its raw form. With the exception of biofuels, LPG has the lowest upstream emissions of any transportation fuel. If Australian households switched to LPG instead of electricity for water heating, space heating or cooking, they could reduce their greenhouse gas emissions by over 50 per cent, according to the gas industry. This would not be true if their electricity was from renewable sources, but it does demonstrate the environmental advantages of LPG over other forms of gas.

Therefore, LPG is the best gas for a sustainable hot water system. However, since it does still produce emissions, it is less sustainable than using renewable electricity. Renewable energy is growing rapidly in Australia. It grew at almost double the world average in 2020. Renewable energy generation capacity added last year surged 45 per cent to 280 gigawatts. This was the biggest increase since 1999, and the International Energy Agency predicts this increase will continue

How do LPG hot water systems work?

There are two types of LPG hot water systems: instant and storage tanks. Storage tanks keep a limited supply of hot water in a tank. When a hot water tap is turned on, the tank releases some of this hot water to the tap. Cold water replaces it at the bottom of the tank. If the tank water temperature drops below a pre-set point, the gas burner fires up and begins to heat the tank using LPG to restore the temperature. In this way, it refills the tank with hot water.

Storage tanks retain hot water in a tank so it is always ready to use. However, this variation uses energy constantly to keep hot water in the tank, rather than heating it as it is needed, as is the case with an instant system. It also means that the amount of hot water available can quickly run out, and the user must wait for more to be heated. 

What is the difference between instant gas hot water systems and storage tank hot water systems?

An instant gas hot water system provides non-stop hot water when the tap is turned on. This is because it continuously heats water as it passes through the system. There is no need for a storage tank as it simply heats up the water immediately for use. As a result, it never runs out of hot water. An instant gas hot water system may use either LPG gas or natural gas.

What is the best LPG hot water system? 

Instant LPG hot water systems are the best for several reasons. While they might be more expensive to purchase, they are overall cheaper to run than traditional gas or electric storage tank water systems. This is because they are more efficient. Instant hot water systems only heat the amount of water that is required. They do not continuously heat and store hot water in a tank which saves energy.

In Australia, instant gas hot water systems account for 21 per cent of all water heaters. The best selling system is the Rinnai Infinity 26. The electric variation of instant water heating accounts for just three per cent of all hot water systems. But, it would be better if more households switched to a LPG hot water system. Using a LPG hot water system can reduce water use greenhouse gas emissions by about 75 per cent.

Benefits of an instant LPG hot water system

Instant LPG hot water systems never run out of hot water. This is regardless of how many other people are simultaneously using hot water. They also guarantee constant temperature control whereas water from storage tanks can fluctuate. As they do not have a tank, they are small and compact. In addition, they are easy to install, indoors or outdoors, and are simple to maintain.

One of the greatest advantages of instant LPG hot water systems is that they avoid wasting power. Some models have a seven-star energy efficiency rating, which is the highest possible rating. The highly regarded Rinnai Infinity 26 has a six-star rating. Similarly, Rheem models are also considered one of the best, with five-star energy ratings. 

Downsides of a LPG hot water system

Nevertheless, there are downsides to using a LPG hot water system in your home. LPG is a byproduct of the fossil fuel industry. Using this fuel perpetuates the extraction, processing and transportation of fossil fuels. Therefore, it contributes to global warming by increasing the number of greenhouse gases in the atmosphere.

The oil and gas industry promotes natural gas and its associated fuel types as a ‘cleaner’ source of energy compared to other fossil fuels. But this is not necessarily the case. In Australia, the sector has successfully hoodwinked the government into subscribing to a ‘gas-led’ recovery to the COVID-19 economic downturn.

This contrasts strongly with the green economic recoveries that most OECD countries are following. It threatens our planet with considerable environmental repercussions as global temperatures continue to rise. Ultimately, renewables are the only source of truly clean energy. 

Is LPG bad for the environment?

LPG, like gas, is less carbon-intensive than other fossil fuels. It is also less toxic. If it leaks, it evaporates into the atmosphere, leaving wildlife untouched. Compared to natural gas, oil and coal, it is a cleaner source of energy. 

However, it would nonetheless be better to switch to renewables instead of LPG. LPG still produces some CO2 emissions through combustion. This contributes to climate change. On the other hand, renewables have a significantly lower carbon footprint. They release very few, if any, greenhouse gases and so do not increase global warming.

Therefore, using a LPG hot water system might have fewer emissions than other hot water systems. But, this would not be the case if electric hot water systems were powered by green energy. Renewables are on the rise. 21 per cent of Australia’s electricity generation came from these clean energy sources in 2019. By 2020, this figure had risen to 27.7 per cent. Progress is being made, but we need to do everything we can to phase out fossil fuels as quickly as possible.