Replacing Your Hot Water Cylinder

Hot water cylinders are the most commonly used hot water heating systems in New Zealand and can last a long time if properly maintained.

The time may come to replace your hot water cylinder if it has broken down or starts to leak, causing isssues at your property. Based on your hot water needs you may choose to replace your current model with a similar one or you may choose to upgrade to a bigger capacity model to suit your needs.

Regardless, it can be a stressful time if your old model is no longer working and you’re stuck without hot water. You will need to be informed and you may require expert advice to make the right decision under the time constraints.

Replacing a variety of hot water systems

Sumich are specialised in replacing mains & low pressure cylinders as well as other models including Rinnai and Rheem hot water cylinders. To restore your hot water system get a free hot water replacement quote from our experts by either calling us on 0800 437 021 or by completing the online form for a free quote.


Hot Water Cylinder Replacement Auckland


Signs that there are hot water cylinder problems

Its never an easy time dealing with a problematic hot water system, however there are some distinct signs that tell you your hot water cylinder is not working properly including:

  • No hot water
  • Low water temperature
  • Knocking or banging noises coming from the cylinder
  • Hot water smells
  • Low water pressure
  • Leaking hot water cylinder
  • Damaged hot water cylinders
  • The discharge valves running constantly

In certain cases and depending on the severity, you may be able to repair your hot water cylinder instead of replacing it. Our team would need to assess your cylinder to identify the issue, and repair the fault.

If you have flowing water, but it is not coming to temperature you may have a faulty thermostat or element, or a blown fuse or power provider ripple control. This can easily be remedied by replacing the thermostat, element or fuse..

If you do not have flowing hot water, the issue may lie with:

  • A blocked tempering valve or strainer
  • Incoming water problem
  • Various possible blockages
  • A damaged valve.  

If you have very low temperature or water temperature fluctuations, possible faults include:

  • Incorrect controller or thermostat settings
  • A damaged element
  • A damaged or incorrectly set tempering valve
  • A damaged diffuse
  • A possible blockage
  • A tapware issue.

To remedy this, you may need to change the thermostat, controller or tempering valve settings.  

If you hear a knocking or banging noise, this can be caused:

  • By replacing from a low-pressure system to a mains pressure system.
  • The existing pipe work may not be fixed properly
  • The plumbing could be prioritised incorrectly
  • There could be too much pressure
  • The valves could be damaged or unsuitable.

To stop this from happening, you can find and fix the pipe work; improve the existing priority; or install a water hammer arrestor. 

Smelly hot water can be caused by:

  • Bacterial growth due to the water temperature not meeting minimum HWC temperatures.
  • It can also be due to accumulated sludge or rust caused by insufficient protection against electrolysis as the anode rod breaks down.
  • If the smell comes from the hot water cylinder itself, it is typically caused by older cylinders or cylinders that have been slowly leaking over an extended period of time, due to a threaded element or a minor crack.

The only possible outcome may be to replace the hot water cylinder as the issues can be too severe to remedy.

An existing low water pressure issue may be caused by:

  • A damaged pressure reducing valve
  • Incoming pressure changes
  • Tapware or related valve issue
  • Excessive sludge or debris blocking the outlet

New low water pressure issues can be caused by:

  • Faults or blockages with the taps and valves,
  • Issue with the incoming pressure.

Leaking hot water cylinders can be caused by a range faults, these include

  • Loose connections
  • A faulty element washer
  • A faulty valve
  • Excessive pressure
  • Thermal expansion or contraction
  • A cracked tank. Usually a cracked tank is cause by excessive pressure, overheating or old age.

Sumich Plumbing will be able to repair the leak but replacing the unit could be more successful remedy. 

If the discharge valves are running constantly

It could indicate the valve may be faulty or debris are blocking the valve spring. To remedy the problem, you can attempt to discharge water from the valve to dislodge debris by following the manufacturer’s instructions. You should also maintain the valves regularly and repairing or replace any faulty valves. 

Your decision to repair or to replace the hot water cylinder has to be considered carefully and should start with the age of your cylinder. A traditional hot water cylinder can last anywhere between eight to twelve years, if your cylinder is at the end of this range you may consider replacing it.

Discoloured or Rust Coloured Water

Hot water cylinders have an anode rod inside to help protect the interior lining by attracting corrosive particles by electrolysis. As time goes on, the rod can corrode preventing it from functioning properly. At this stage, the inside of the tank will start corroding, this will signal the end of the hot water cylinder’s life span. Signs that this may be happening include discoloured or rust-coloured water and a metallic taste to the water. 

You may choose to replace your current hot water cylinder with a similar model, that could be a low pressure hot water cylinder or a mains pressure hot water cylinder. Or you could take the opportunity to replace your hot water system to a different type that is more suited to your hot water needs, alternative options include gas continuous flow hot water system, a hot water heat pump system or a solar water heating system.

Hot Water Cylinder Replacement Cost

We understand that costs play a key role in deciding whether or not to replace your hot water cylinder, however It’s difficult for us to provide a cast-iron, final price without a full assessment. 

Your decision may largely be based on the cost of disassembly, removal, installation and ongoing running costs. However, as a ball park figure, replacing a new hot water cylinder can cost anywhere between $2,000 and $3,000, the running costs for the average three-person household are approximately $560 to $1,000 a year. 

Ultimately, the cost of hot water cylinder replacement is dependant upon several key factors including: the size of the hot water cylinder, model and type of the replacement cylinder, the replacement job itself, installation and connection.

A hot water cylinder is comprised of several parts and valves, along with an outer and inner cylinder. There are several places where a problem might occur, therefore there are a number of possible solutions when it comes to repairs and costs.

A replacement part and associated labour may be just a couple of hundred dollars. A new hot water cylinder for an average household of four people will usually cost between $2000 to $2500. And a new continuous flow hot water system averages $2750 to $3750 upfront (but will save you money on your water use).

It’s important to review your needs, how your household uses hot water, and the other factors mentioned here in addition to cost. The experienced team at Sumich Plumbing & Drainage will take a full-picture approach and help you decide what is best for your needs and budget. Give us a call – we’d be happy to help!

What Is Your New Cylinder Going To Be?

A key factor to the total cost will be dependant on which type of hot water cylinder you will be replacing. 

Any of these hot water cylinders can be replaced by the skilled staff at Sumich. We can provide you with some choices and go over the advantages of switching from a low pressure hot water system to one that operates on mains pressure.

If you are noticing problems with your hot water cylinder get in touch with our team and we will come over and assess the situation. We will then be able to provide you with a detailed plan of action, as well a costs breakdown of the project.  

To get a free hot water cylinder replacement quote, please call us on 0800 437 021 or complete our online quote form.

Gas vs Electric Hot Water Systems

There are several things to consider if you’re trying to decide whether to heat your [...]

Why Is My Hot Water Cylinder Leaking?

f you notice a pool of water around your hot water cylinder, you may have [...]

Hot Water Cylinder Problems

Generally speaking, your hot water cylinder is a low maintenance appliance. When it's working properly, [...]

Recommended Hot Water Temperature NZ

Did you know that there is legislation in New Zealand that determines and regulates how [...]

5 Questions to ask yourself before buying a hot water cylinder

There is a range of hot water cylinder manufacturers that make the highest quality models, [...]

Your Guide To Hot Water Systems

If you’re building a new home or are considering changing or upgrading the hot water [...]

Auckland Plumbing & Drainage Solutions

Call now: 0800 437 021

Get in touch

Don’t forget to mention Free Quote!*