Elgas LPG Gas Blog

Best Hot Water System: Reviews & Prices

Want to find the best hot water system?

Concerned that what your plumber recommends may not be the best choice for you or your home? 

What size hot water service do I need?

Want to find the best price?

We review hot water system types and prices, comparing the pros and cons of the various alternatives, to help you make an informed decision.

Best Hot Water System - Best Gas or Electric Hot Water System

Best hot water systemThe best gas tank, instant or electric hot water system has the right combination of good reviews, ratings, size, price, the type of system, the brand and the specific model you need. Picking the best gas or electric hot water system is obviously a subjective judgement, but that will be true of anyone trying to name the best of anything.

Many people believe that tankless are the best hot water system type. The best instant hot water systems are now available in 7 Star units. The best instant hot water system brands include Rinnai and Rheem. The best electric hot water systems are probably from Rinnai, Rheem or Dux.

Some say gas and others say electric is the best hot water system. The top selling Rinnai Infinity 26 is the best instant hot water system Rinnai makes. The Rheem Stellar would be Rheem's best hot water system.

Types include solar, gas, electric, heat pump, tank and tankless continuous flow whilst brands include Rinnai, Dux, Rheem, Bosch and others. 

Given that hot water often consumes around 25% of a home’s energy budget, you really want the best system.

These decisions will affect the upfront cost of purchase and installation and the ongoing running costs.

Solar hot water system boosters can be electric, natural gas or LPG.

Solar hot water system option may take a number of days to install.

Heat pump hot water units can be very noisy.

On demand gas water heaters are also called tankless or continuous flow.

Compare the Best Hot Water Systems Prices

Compare prices for all the best hot water systems brands including Rinnai, Bosch, Kelvinator, Rheem, Dux and AquaMAX.

Click on your category of interest to compare prices:

Continuous Flow Instant Hot Water Systems Prices

Storage Tank Hot Water Systems Prices

Solar Hot Water System Prices

Hot Water Service – A Review of Your Choices

Electric Storage Hot Water Systems

Electric Storage Hot Water Systems

Also known as hot water tanks or cylinders, these have been the most common hot water system in Australia for decades. 
Unfortunately, with the rising cost of electricity and the high greenhouse gas emissions associated with generating the required electricity, these units are falling out of favour.  
In fact, the government has passed legislation to try and limit their use.
Electric water heaters that heat all day are your most expensive option.  
Off peak electric storage units are better, as off peak electricity tariffs are lower.
However, as they only heat water at night, they need to be quite large to make sure you don’t run out of water during the day. 
So, some of the electric savings is offset by the fact that you need to heat a larger tank.  
The bigger tank would also cost more to purchase.
Still, many people with an old electric unit are tempted to replace like-for-like and continue using an electric storage unit. 
It is a quick, one day fix and the upfront costs are not prohibitive.  However, the long term disadvantages need to be considered.

Gas Hot Water Systems Review - Storage Tanks

Gas Storage Hot Water Systems

A gas hot water systems review would involve a comparison between gas storage tank systems and tankless continuous flow systems, sometimes called instantaneous gas hot water systems.  

The installed cost of a gas storage unit is close to that of the electric units, especially if you already have gas at your home. 

A gas storage hot water system appears similar to an electric tank or cylinder, the primary difference is that the electric heat element is replaced with a gas burner.

Gas storage hot water units are energy efficient, particularly if you choose one of the new 4 or 5-Star models, and they have much lower greenhouse gas emissions. 

Also, there are no time-of-day tariff issues with gas.  

This means that gas storage units do not need to be as large, as the gas burner can operate whenever required.

You can also choose a gas storage system no matter where you live, as they are available in both natural gas and LPG models.  
Installation is normally accomplished within one day.

Solar Hot Water System

Solar Hot Water System

A solar hot water system can have some of the lowest running costs and greenhouse gas emissions, but they are typically the most expensive to install, with installed cost as much as 4X that of a storage unit, even with rebates.
Solar hot water systems are usually equipped with a booster unit for periods without sufficient sunlight. 

Solar hot water system boosters can be electric, natural gas or LPG.  

It is important that you purchase a solar hot water system with a sufficient number of panels and tank storage, so that the booster is not overused, or the running costs will be higher.  
Your roof configuration also needs to be compatible with a solar system. 

Solar hot water system option may take a number of days to install.

Heat Pump Hot Water

Hot Water Heat Pumps

Heat pump hot water systems heat your water by extracting heat from the ambient outside air, in the same way that a reverse cycle air conditioner would heat a room.  

The heat pump hot water is kept in a tank, similar to storage systems.  

Heat pump hot water can be quite efficient and have low greenhouse gas emissions but, once again, the upfront costs are substantial.

Heat pumps also have a couple of weaknesses that have caused them to lose popularity in the last few years.  
Because they essentially incorporate an air conditioning unit, there are many more moving parts and the maintenance costs tend to be higher than for any of the alternatives.
They also have the dubious distinction of requiring as many as 3 trades for repairs: an air conditioning mechanic, a plumber and an electrician.
The other issue is noise.  
If you live in close proximity to your neighbours or if you like to leave your windows open, the compressor and fan noise can be problematic. 
This is especially true if the unit is set-up to run off-peak.  
It can easily need to run all night because of the colder ambient temperatures after dark.

Heat pump hot water units can be very noisy.

Gas Hot Water Systems Review - Tankless Continuous Flow

Gas Hot Water Systems Review - Tankless Continuous Flow

Gas hot water systems reviews for tankless continuous flow (instantaneous) primarily involves flow rates and star ratings, as well as brands.

Tankless continuous flow gas hot water systems provide hot water on demand whenever you turn on the tap, as you need it.
These units only heat the water as it passes through so there is no storage tank.  
This also means you never run out of hot water. 
With tankless systems, you only need to heat the water to 50°C, as the prevention of bacterial growth is NOT an issue with tankless units, as it is with all of the other alternatives that have tanks.
While the running costs are not quite as low as solar and heat pump units, the upfront costs are much lower. 
Greenhouse gas emissions are also much lower than electric storage.  
Available in both natural gas and LPG versions, these units are very energy efficient, with 5-Star or better ratings. 

Instantaneous Electric Hot Water Systems

Instantaneous electric hot water systems are also available.

However, they are not very common.

As they are used during the day, you pay the full electricity tariff, as opposed to off-peak electric storage units.

This higher cost of operation is the main reason for the rarity of instantaneous electric hot water systems.

How a Tankless Water Heater Works

Schematic of continuous flow hot water heaterIn summary:

• Cold water flows into the water heater when a hot water tap is opened inside your home.

• The water flow is detected by a sensor that ignites the gas burner, to heat the water in the heat exchanger.

• The water typically follows a serpentine pattern through the heat exchanger, absorbing as much heat as possible.

• An electronic control unit modulates the gas burner to maintain a set water temperature.

See all the details on:

How a Tankless Hot Water Heater Works

Combustion Efficiency & Star Ratings

Star ratings encapsulate both a start-up heat up factor for each appliance and combustion efficiency.

As a result, combustion efficiency for each star rating can vary a bit.

However, if we look at combustion efficiency in isolation, it does make it a bit easier to understand what it all means.

When it comes to energy efficiency, many believe that 6-7 Star tankless are the best hot water system, especially based on the affordable initial investment.

The following are all approximate but will give you a good idea what to expect based on what star rating you choose:

4 Star = 73%

5 Star = 80%

6 Star = 87%

7 Star = 94%

Size and Aesthetics

Bosch 26e

Storage tank hot water heaters are big, especially the electric off-peak models. 

Even when installed outdoors, the size can get in the way, particularly with today’s smaller lot sizes. 

Having this large object next to your house also does nothing for the appearance of your home.

At about the size of a small suitcase, tankless water heaters are much smaller than a traditional storage tank heater. 

Mounted flush against the wall, the smaller tankless units take up less space and are also more aesthetically pleasing, as they don’t dominate the exterior appearance of your home.

So, when considering size and aesthetics, once again tankless units are the best hot water system.

Health & Safety

Storage tank hot water heaterWith storage tank water heaters, there is the potential for bacteria growth within the tank. 

The World Health Organisation -- WHO -- recommends that stored hot water be kept at a minimum of 60°C. 

Unless a minimum of 60°C is maintained, hot water tanks can be a breeding ground for Legionnaires’ disease, or Legionellosis, that is caused by a bacterium, Legionella pneumophila. 

It is a respiratory disease that can cause severe pneumonia and is sometimes fatal.

However, Canadian studies have shown, even when the thermostat is set at 60°C, a high percentage -- approximately 40% -- of electric water heaters remain contaminated. 

This is because of the lower temperature, of about 30°C to 40°C, at the bottom of the tank.

With tankless systems, the prevention of bacterial growth is not an issue, as there is no stored water in which bacteria can breed. 

Tankless systems can also be set at 50ºC, so the risk of scalding is greatly reduced without the need of a tempering valve.

What Size Hot Water System Do I Need?

Don't Calculate by Number of People or Bathrooms

The sizing information available is very confusing because manufacturers, and others, are trying to provide a simplified answer to a complicated question. 

Some suggest that you calculate by the number of bathrooms in your home while others say to go by the number of people in your family. 

Also, in many cases, their recommendations are based on the worst case scenarios, assuming higher consumption than your actual water use.

Buying Too Large Wastes Money

The result is that many people end up buying a larger system than they actually need. 

This costs them extra money when they buy the hot water system and will increase the ongoing operating costs, in many instances.

Factors to Really Consider

Simultaneous use is one of the fundamental determining factors.  

The number of people in your home combined with how and when they use hot water is the key. 

  • Do they all take showers at the same general time of day? 

  • Do they take showers simultaneously in different bathrooms?

  • Do the showers have WELS 3 Star Rated Showerheads (maximum 9L/Min) or standard 18 to 25L/Min showerheads?

  • Do some prefer baths, which use more hot water? Is the bath or spa oversized, requiring even more hot water?

  • Do you run the washing machine, using hot or warm water, while people are showering?

  •  Is your dishwasher connected to the cold or hot water? If hot, do you use it while hot water is being used elsewhere?

Showers Are the Key

Showers use the most hot water in a home.  People generally shower for 5 to 10 minutes. 

Assuming you have a 3 Star shower head and you mix in some cold water with the hot, the typical hot water consumption would probably be in the 7 litres per minute range. 

If you also assume an 8 minute shower, you will consume about 56 litres of hot water per shower or a family of four would consume 224 litres. 

The use of WELS (Water Efficiency Labelling and Standards) 3 star rated showerheads is an important factor in saving water and energy whilst reducing the size and cost of the hot water system required.

Hot Water Tank ExampleRinnai HOTFLO 170 gas hot water system

In the above example, if all four people take their showers in the morning, you would only need a storage hot water system with 224 litre first hour capacity, regardless of how many take showers at exactly the same time.  

This all presumes that you are not using any other hot water devices at the time.  

The use of additional hot water, after the shower period, would depend on the hot water system’s recovery time required to achieve full temperature.  

So, with a larger family or house guests, a bit of scheduling may be required to avoid the need for a larger unit.

Off Peak Electric Issues

Off peak electric storage units are a completely different story. 

Inasmuch as they only heat water at night, they need to be quite large to make sure you don’t run out of water during the day. 

So, some of the electric savings is offset by the fact that you need to heat a larger tank. 

The bigger tank would also cost more to purchase.

Tankless Hot Water Example

Bosch 21e tankless gas hot water systemFor a tankless continuous flow unit, it would depend on how many showers are being used simultaneously. 

Using the example above, if it’s two showers, then you only need a unit with a minimum flow rate of 14L/min. 

If you have 3 people showering at exactly the same time, you would need a minimum 21L/min.  

This does assume that you are not using other hot water devices simultaneously. 

Recovery time is not an issue with continuous flow units, so even a large family with guests would not run out of hot water.



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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.