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Choosing the right hot water system # blog 7

Topics discussed below

  • Introduction
  • budget
  • family size, family ages
  • house types
  • house type
  • house size
  • fuel type
  • Like for like hot water systems
  • open to new ideas
  • hot water system tariffs
  • peak usage
  • summary


Many of us take hot water for granted, and why not, it seems to be always there when we want it.

I want to give you some more information today about factors that contribute to making the best decision when choosing a hot water system.


Probably the first and most important question asked when you need a new hot water system, how much will it cost?

If you cannot afford the best 300 Litre hot water system, but this is the size you need, then you need to look at how you can make it work,  rather than down sizing and buying a 250 litre for example, because you will run out of water at some point and this will affect how hot water is used in your home.

Let’s look at your options if a senator like this pops up;

Option 1 – buy the hot water unit on finance. A good percentage of plumbing companies now offer finance and allow you about 6 months to pay the hot water system off.

Option 2 – Ask your plumber if they could recommend a cheaper storage hot water system brand. Bunnings have a good range of cheaper storage hot water systems. They are all Aussie approved with a water mark.

There are also many online stores which offer free delivery hot water systems at a reasonable price. Saying this, do your homework before purchasing, make sure the company is reputable and all products have good warranty periods. Look at the website reviews too.

We plumbers get used to a brand and stick with it, this doesn’t mean that there are not other just as good options out there.

I find new items daily which are awesome and have been around for years, yet I only just discovered them! My point, keep looking and have an open mind.

Option 3 – look at a continuous flow style of hot water system. They are slightly cheaper to buy and install, yet provide a never ending supply of hot water and can typically provide around 26 litres of hot water per minute, up to 32 litres for the largest unit, this would cope with 3 showers running at once. Natural gas is a preferable fuel source over lpg here because they do chew through the gas when in operation, but no gas consumption when dormant.

Family size and family age ranges

This one is quiet obvious, the bigger the family, the bigger the daily hot water usage.

We need to also include the age brackets here. Despite the common belief that females take longer showers, a comprehensive study out of the UK proved this to be incorrect. There is very little difference between the sexes, with the average shower being between 7-8 mins.

Let’s have a look at why this is important.

If we take a family of 5 for example with two adults with three young kids, it is unlikely the kids will shower in the morning but the adults probably will where as if you get a family if 5 with 3 kids over 12, it is more likely that the showers will be running both morning and night consistently through the week, meaning the showers will be used approx 490 minutes over the week compared to 343 mins for the family of five with young kids.

Obviously, every family is different, this is why understanding the clients water habits are essential.

My kids can spend 30 mins in the shower playing on a cold day.

The table below can be used aaa guide to help you give your plumber an idea of your situation.

House type

Do you live in a unit? Do you live in a house with one level or two and have lots of roof space? These are all important areas to look at to help you narrow down your options.

If you have a low set home with lots of room and roof space then your options are nearly limitless whereas if you live in the cbd in a small unit with one bed and no balcony we are limited in our options.

House size

If you have a larger house with multiple bathrooms, then location of your hot water system is paramount. Poor location can mean a huge amount of wasted water while you wait for the hot water to come through.

Quite a few houses are no inst alling several hot water systems to combat this. This design allows much less waste in water and you get to install smaller hot water systems as they are now only serving maybe one bathroom and a sink each.

Fuel Type

We have a choice of;

1. Natural Gas

2. LPG

3. Electric

4. Heat Pump

5. Solar

This is where your personal circumstances come into play. If your budget is not a constraint then Solar could be a good option, because it costs a little more to purchase and install but the cost savings through the life of this hot water system are great and they generally provide a good warranty length.

All these options have their own merits and should al be considered against your own personal circumstances.

The graph below should help give you an idea of what other residents in your state are doing.

Like for like but modern

If you replace an old hot water system with the exact or very similar model then the installation costs will be far cheaper than something completely different.

So If you happy with your old hot water system and are not worried about upgrading to a newer model then get your plumber to install a “like for like”. Hot water system, it could save you a few hundred dollars .

If you are willing however to do a little bit of research yourself and look for a better hot water unit, but are still on a bit of a budget. Make sure the cold water inlet and the hot water outlet are similar to the one you are removing. This makes life for your plumber much less time consuming , saving you money in the process.

Saying this, a plumber should be able to drain your old hot water system and install the new one in around 3 hours. This is based on the hot water system being in the same location and the drainage and power are all correct and there to connect to. Sometimes things go great and you can be in and out in the hour others have taken longer when drains are not close by and the previous pipe work was installed incorrectly.

Open to different set up type

Are you open minded about the type of hot water system you are willing to install.

I have been a storage hot water system person all my adult life but I recently went to the Brisbane plumbing and gas expo and got introduced to an instantaneous hot water system that is blue tooth compatible to my iPhone and can be used to set temperatures for each person individually. It also tells you your hot water usage for different times of day. I am going to purchase this system when mine dies in the next year or two.

Would you be open to change?

Google home has voice activated showers with hot water voice control!!!

Gas lines/ additional wiring etc

hot water tariff

Your power provider will have a tariff which will only heat your hot water system during an off peak period. This really only applies to electric storage type hot water systems, but if taken up can save you hundreds per year.

The only problem I have noticed with this tariff is that if you have a big day of showers and washing laundry etc, it is possible to run out of hot water which will not be heated until the off peak tariff time kicks in.

Peak period usage

One of the most critical factors in determining your hot water system size is how much hot water are you likely to use during the busiest hour of the day.

For example a larger family may have 2 showers running for 30 mins each night. If we allow approx 5- 6 litres of hot water per min per shower, this equates to between 300 – 360 litres of hot water for our peak 30 mins of the day. A 315 litre hot water system would have enough recovery over the 30 mins to ensure the hot water did not run out , but this is where an off peak tariff may catch us out.

An instantaneous style hot water system is becoming more and more popular because one unit has the ability to deliver up to 32 litres of hot water, (certain models only), and it provides an ever ending supply of hot water.


Yes a hot water system needs to installed by a licensed plumber but inevitably the type of hot water system you choose is your choice.

Please see the table below as a guide only. This chart only uses a few factors but hopefully gives you an idea of how to start choosing the right hot water system for you and your family.

If you have any questions relating to hot water systems please comment below or visit me at [email protected] I will try to answer your questions as quick as I can.