Have you ever wondered about how many types of hot water cylinders there actually is?

We have complied a list of hot water cylinders for you, showing application, benefit and disadvantages helping you make an educated decision before purchasing your next hot water cylinder.

First of all we need to separate the PRESSURE TYPES from the MATERIAL TYPES. In New Zealand one can purchase almost any material type at three different pressures.

Most common pressure types available in New Zealand (Domestic Applications) 

• Low Pressure, open vented systems where the pressure is provided by a cold water storage tank, open vent or rely on a pressure-reducing valve to reduce the pressure below mains pressure supply.
  Typical Pressure: 30 – 75 KPA, typically 3 – 7.5 metrets Head

• Medium Pressure, open vented systems where the pressure is provided by a cold water storage tank, open vent or rely on a pressure-reducing valve to reduce the pressure below mains pressure supply.
  Typical Pressure: 75 – 120 KPA typically 7.5 – 12 meters Head

• Mains Pressure, with a working pressure equal to incoming supply. Pressure can be limited to any requirement but using the appropriate valve work.
  Typical Pressure: Ranging from 120 – 1400 KPA (Domestic Supply is typically 350 – 750 KPA depending on requirement)

Mains pressure water heaters are the predominant type of new installation in Australia and New Zealand.

COMPARISON TABLE OF HOT WATER STORAGE TYPES AT DIFFERING PRESSURES. 

The following hot water cylinder material types are available in New Zealand

CYLINDER MATERIAL	PRESSURE	ADVANTAGES	DISADVANTAGES
Enamel Lined	Low Pressure Mains Pressure	– Supply of mains pressure – Low cost supply Installation – Very common in NZ	Requires sacrificial anode 8 – 20 year life expectancy
Copper	Low Pressure Medium Pressure	– 15 – 40 year life expectancy – Large Storage at low cost – Can be used for high temperature power sources such as wetbacks and solar.	– Not suitable for most  modern tap ware – Requires sacrificial anode – Low pressure
Stainless Steel	Low Pressure Mains Pressure	– 15 – 50 year life expectancy No sacrificial anode required – Can be used for high temperature power sources such as wetbacks and solar.	– Large storage at high cost – Higher supply cost – Come with the longest warranties