Gas hot water heating
Water heating is generally the biggest energy user in any home, typically using about 40% of all household energy. The economy and effectiveness of gas make gas water heaters suitable for virtually all hot water applications.
There are two types of gas hot water heaters available: continuous flow units and hot water storage cylinders.
Each is highly effective and designed to meet a variety of different requirements and are available as either internal or external units.
Placement of hot water heaters
The hot water system should be placed as close as possible to the most frequently used hot water outlet or outlets – such as the kitchen – to minimise the delay time for hot water delivery. Check the manufacturer’s recommendations regarding placement of the selected hot water system.
Both external and internal hot water systems must also be situated in compliance with the flueing requirements of Part 2 of NZS S5261: 2003, see Ventilation and flueing for further information.
Most gas hot water heaters require a power source.
Capacity guidelines
When determining what size heating system to use, the following should be considered in calculating the amount of hot water required:
- The number of people in the household. Teenagers and adults use more hot water than children.
- Appliances such as dishwashers and washing machines should be taken into account as an extra person.
- The number of water outlets in the building/dwelling.
- Different bathroom fittings use different amounts of water. For example, massage shower heads use as much as 30 litres of water per minute.
This chart is an indication of how many litres of hot water are usually needed for different household activities:
Activity Type |
Number of litres used per activity |
| Bathing | 70 to 120 litres (more for spa baths) |
| Showering | (standard shower head) 8 to 12 litres per minute |
| Bathing an infant | 10 litres |
| Hand washing | 5 to 10 litres |