The Role That a Hot Water Cylinder Plays in Your Home
In modern living, hot water is something most of us take for granted, until it runs out. Whether you're enjoying a morning shower, washing the dishes or doing laundry, your hot water cylinder is quietly working behind the scenes to keep daily life running smoothly.
But what exactly is its role and why is it so important?
Let’s explore the central part that a hot water cylinder plays in your home, how it functions and why keeping it in good condition matters.
What Is a Hot Water Cylinder?
A hot water cylinder is a large, insulated tank that stores and heats water for domestic use. It acts as a reservoir of ready to use hot water, available on demand for your taps, showers, and appliances.
Hot water cylinders are typically powered by:
Electricity
Gas
Solar panels (with electric or gas backup)
Wetback systems (connected to wood burners)
They come in two main types:
Mains pressure (unvented): Delivers strong water flow, more common in modern homes.
Low pressure (vented): Older system with lower flow, often still found in older New Zealand houses.
Why Is It So Important in Your Home?
1. Consistent Hot Water Supply
The primary role of a hot water cylinder is to ensure you have reliable hot water on tap. Instead of heating water as you use it (like a continuous flow system), it heats and stores a fixed amount typically 135L to 300L ready for use throughout the day.
2. Efficient Energy Use
Hot water cylinders are typically insulated to retain heat, meaning they can store heated water for hours with minimal energy loss. Combined with off peak electricity plans or solar power, they offer a cost effective way to heat water efficiently.
3. Supports Multiple Water Points
One of the key advantages of a storage cylinder is that it can deliver hot water to multiple taps or appliances simultaneously. Whether someone’s showering while the dishwasher is running, there’s no major drop in temperature assuming the cylinder is large enough.
4. Essential for Daily Routines
Hot water is integral to:
Personal hygiene – showers, bath, hand washing
Kitchen use – washing up and food preparation
Laundry – especially when washing in warm or hot cycles
Cleaning – mopping and general household cleaning tasks
How It Works: A Simple Breakdown
Cold water enters the cylinder through the inlet valve.
A heating source (element, gas burner, or solar coil) heats the water inside.
A thermostat maintains the set temperature.
Hot water exits through an outlet pipe when you turn on a hot tap.
Cold water enters to refill the space, and the heating cycle begins again.
Some systems also have:
A tempering valve to control water temperature to a safe level.
A pressure relief valve to prevent over pressurisation.
What Happens When It’s Not Working?
When a hot water cylinder fails or becomes inefficient, you might experience:
No hot water
Inconsistent temperatures
Low water pressure
Strange noises or leaks
These issues can disrupt daily life and in worst cases, lead to expensive water damage or energy waste.
What to Check When Things Go Wrong
Here’s what to look for if your hot water cylinder isn’t behaving:
No Hot Water
Check the fuse/switch on the main electrical board.
Test the element – it may need replacement.
Inspect the thermostat – a faulty one may prevent heating.
Low Hot Water Pressure
Common in low pressure systems.
Look for a partially blocked tempering valve or inlet filter.
Upgrade to a mains pressure cylinder if pressure is consistently poor.
Water Too Hot or Cold
Thermostat settings may be too high or low.
Tempering valve could be faulty or need adjustment.
Leaking from the PRV
A small drip during heating cycles is normal.
If constant leaking, the valve may be worn and need replacement.
Noisy Cylinder
Sediment build up in the tank can cause popping or rumbling.
Consider flushing the tank or installing a filter on your cold water inlet.
Rust-Coloured Water
May signal corrosion in an older cylinder, especially steel tanks.
Time to consider replacing the unit with a stainless steel one.
Think it Might be Time to Call a Professional?
While you can check and troubleshoot some issues yourself, most of the time you should always contact a licensed plumber or gasfitter to check in case of electrical issues.
At Garcia Plumbing and Gas, we're here to support you every step of the way. Give us a call on 022 046 1463 or click “Get in Touch” and we will get your hot water cylinder fixed right away.