Most people are surprised to know that hot water makes up 30% of an average household’s energy consumption?
So, choosing the right hot water system can make a substantial difference to the running costs of your home.
There are two main types of hot water systems:
(A) Storage hot water
(B) Continuous flow / Instantaneous hot water.
A storage system maintains hot water in a tank and provides a relatively quick supply of hot water but has a limited storage capacity.
A continuous flow system rapidly heats up an unlimited amount of water on demand when you need it but at a slightly reduced water pressure which can result in slower delivery of hot water.
Both of these systems can use gas or electricity and or solar power to heat the water, however, they each have distinct advantages and disadvantages.
Electric Hot Water
Advantages = low upfront cost to buy and install, can be installed inside or outside and can be programmed to take advantage of “off-peak power” periods.
Disadvantages = more expensive running cost and higher greenhouse gas emissions, so generally discouraged as a long term hot water solution.
Gas Hot Water
Advantages = similar upfront costs to buy and install but lower running costs compared to electric systems due to lower natural gas prices. Produce less greenhouse gas emissions.
Disadvantages = must be installed outside, continuous flow systems need a much larger gas supply and have slower hot water delivery. Areas that only have LPG gas supply will have much higher running costs for gas hot water.
Solar Hot Water
Advantages = can reduce your hot water energy consumption by up to 80% and solar systems are the most environmentally friendly option. May be eligible for government rebates.
Disadvantages = high upfront costs for purchase and installation, solar systems require gas or electric boosters for hot water consumption at night or on cloudy days.
Other hot water system considerations
Electric Heat Pump Systems
Heat pumps are a much more economical alternative for electric hot water and work like a fridge or reverse cycle air conditioner where they draw warm air into the system and condense it to heat the water stored in a tank. However, they are more suitable to a warm climate and are more expensive to purchase than a conventional electric system.
Ring Mains System
In larger new homes (i.e. 300 sqm +) the time lag in hot water delivery to the taps and appliances can be a significant problem and can waste a lot of water. The best solution to reduce this hot water time lag is to install a hot water “ring main” and circulation pump throughout the house. This will give you instant hot water at any tap in the house but will increase your running cost by 20-30% and will add $2,000.00 to $3,000.00 to the plumbing and installation cost.
What I recommend to my clients
1. For smaller homes or town houses 300 sqm or less, I recommend a 200 to 250 litre gas storage hot water system OR a 26 to 32 litre per minute gas instantaneous hot water unit.
2. For larger new houses or renovations 300 sqm or more, I recommend a 250+ litre gas storage unit with a ring main and circulation pump.