What size hot water system do I need?

What size hot water system do I need?

Whether you’re working on a new build or your existing hot water system is old and needs to be replaced, we can help. Here at Murphy Plumbing, we provide a variety of hot water systems in Newcastle, installing them, servicing them, and repairing them. With the number of options available it makes sense to spend a bit of time learning more about the different kinds of hot water systems so that you can choose the one that makes the most sense in your home. Choosing the best sized hot water system for your needs can be a little daunting, which is why we have put together a guide to help you out. Firstly you will need to evaluate capacity versus consumption to decide on the size which is based on multiple factors. Here’s what you need to know. 

Running Costs vs. Water Consumption

Hot water system costs graph

Source: NSW Office of Environment and Heritage & Sustainability Victoria

Traditional Hot Water System

The traditional type of hot water system consists of a large tank that heats and stores the water. It’s often the most affordable choice and can work ideally in houses with a large hot water usage. The tank should be cleaned yearly and with proper maintenance can last for up to 12 years. This type of hot water system is sized based on the number of people in your household.

Continuous Hot Water System

If you’re looking at an option that’s more energy efficient than a conventional model, a tankless version is a good choice. It heats water using water filled coils and can heat the water on demand so it’s always available. This option is nice for large families and for natural gas hook-ups. Electrical versions may require an upgrade with installation. This type of hot water system is sized based large households. For example a family of four will probably require a 125–160L tank however this depends on other factors too.

Heat Pump Hot Water System

This kind of hot water system uses heat from the air and the ground to heat your water. Also called a hybrid hot water system, it costs more for installation, but can save you up to 60 percent on your energy bills, making it a cost saving investment over time. This kind of hot water system doesn’t operate well in colder areas and requires several feet of clearance for installation, as it’s usually placed on top of an appliance. For example a family of four will probably require a 270-315L hot water system however this depends on other factors too.

Solar Hot Water System

A solar hot water system heats hot water by using solar panels that are usually placed on the roof of your house. The absorb heat from the sunshine and transfer it into the hot water system, where it’s turned into hot water. Solar hot water heaters are ideal for warm, sunny places, but may not work as efficiently if it’s cloudy or overcast. They are also more expensive than other types to install but could save you some money on your energy bills in the long run. This type of hot water system is sized based on the number of people in your household. For example a family of four will need about four square metres of solar collector and a 300–360L tank. This is the average but specific details will need to be considered.

Questions to consider:

  • How many people live in your house?
  • How much water do you use?
  • When does everyone in your home shower?
  • When do you use your hot water?
  • Do you have a dishwasher?
  • Does your washing machine use hot water?
  • What type of shower head do you have?
  • How many shower heads do you have?


If you need help deciding between the different types and sizes of hot water systems in Newcastle, call us here at  Murphy Plumbing today or fill out our online contact form.