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Let’s face it: When it comes to hot water, all you want is to be able to turn on the tap when you want and get the steaming hot water you need and expect. In reality, however, it’s a little trickier than that – and why’s that? Because there’s an awful lot of great but vastly different technology types out there – and they all come in different sizes and capacities.

So after making your choice between an electric or gas, instantaneous, solar or heat pump, tank or tankless, your next question is naturally ‘What size hot water system do I need?’

It’s a question best answered by the local Melbourne plumbers, who spend each and every day matching hot water users with precisely the hot water system for their home, lifestyle, preferences, family size and budget. And, based on that expertise and experience, that’s exactly why we’re here to help with some simple advice.

First, it’s important to reiterate that the answer to what size hot water system you’ll need depends on the type of hot water system you’ve selected. Let’s break down the main ones:

Traditional or ‘tank’ systems:

You know what they look like – a big cylindrical tank, inside which is the water typically heated by electricity, gas, solar power, or ‘heat pump’ heating technology. Once heated and stored, the hot water is there, ready to be used as you see fit.

However, once that tank runs dry, you’ll have to wait for the system to heat up more – which means a cold shower for you in the meantime. For your choice, what that means is matching the actual tank size to your family size and typical daily usage – the more hot water-hungry people, the bigger the tank.

Instant/continuous flow systems:

If your usage is less predictable, though, with some days needing a lot of hot bath and shower water but others when not a long is happening at all, an instantaneous or tankless system might be the way to go.

In this case, the question isn’t really ‘What size hot water system do I need’, but rather ‘What capacity hot water system do I need?’. That’s because while an instant hot water system will keep churning out hot water from a single hot tap, running multiple hot water outlets all at the same time will cause your smaller-capacity system to struggle.

What size hot water system – Frequently Asked Questions

To narrow down your choice even more, we’ve broken down all of the most common questions that people looking to size the ideal hot water system installation for their home or premises tend to ask:

1. How much water do I use each day?

If you’re the Average Joe or Jill, you probably use just shy of 50 litres every day. As you browse those tank or capacity sizes, it should therefore be quite straightforward to find a match for your household – remembering to factor in whether your water usage is average, below average, or above average.

2. Is a bath per day still ‘average use’?

Actually, no. If you love a hot bath each and every day, that will cost you about 100 litres – making you an above average hot water user. A typical shower, though, uses only about 18-20L.

3. Should I just buy a huge system to be on the safe side?

If you have deep pockets, that’s one way to go – but bear in mind that if your system really is too big and powerful for your home’s needs, you’re simply paying unnecessary money up-front for a big unit, and then for the rest of time heating up a lot of water that you’ll rarely use.

4. Ok, so what size hot water system do I need, then?

As we’ve tried to demonstrate, there’s no simple answer to that question, because it depends on how you answer questions like these:

  • How many people use hot water in your house?
  • How much water does each person use?
  • What time of day is your ‘peak’ hot water usage?
  • Does your dishwasher or washing machine use hot water?

To give you a rough guide, we’d probably recommend a small tank storage or continuous flow system for a couple, an efficient heat pump system for 3-4 people, or a large tank for heavy use or bigger families than that.

To quickly put it in numbers:

  • 1-4 people: 90-130L tank
  • 2-5 people: 130-170L tank
  • 4-6 people: 200L tank
  • 5-9 people: 260L tank

Or:

  • 1 outlet per usage: 16 litres-per-minute flow
  • 2-3 outlets per usage: 20L-24L/pm flow
  • 3+ outlets per usage: 32L/pm flow

For the exact answer for you, call an expert

So while there isn’t a definitive answer to ‘What size hot water system do I need’, hopefully this guide has at least pointed you in the right direction. To really get the perfect match for your home, lifestyle and budget, you’ll have to talk to the professionals directly – and here at Ezy-Plumb, we’re always happy to oblige! Need a plumber in Bentleigh, Elwood, Mentone or Murrumbeena? Get in touch today! We work across the Melbourne bayside area and into the south eastern suburbs. With our gas and electrical licenses, we can supply and install new hot water systems from start to finish with guaranteed workmanship.