It has been great to see a distinct shift in people opting for the more efficient and environmentally friendly gas hot water option. What I find, however, is nearly every enquiry I receive initially wants a continuous flow/instantaneous unit. I provide my clients with all the information I can, and many end up opting for a gas storage unit instead.
Below is some comparisons of both options, I hope this allows people to make a clearer decision based on what it is you value or want out of your system.
According to a paper delivered by Professor Alan Pears at the National Plumbing Regulators Conference 2008, gas storage systems may be on par with Gas Continuous Flow/Instantaneous hot water system for gas consumption in houses using 150 to 250 litres of hot water per day.
For an average household a 5 star Gas Storage hot water heater is likely to use 5%-10% more gas than a Gas Continuous Flow/Instantaneous hot water system in 1 year. it's important to consider however, unlike a Gas Continuous Flow/Instantaneous hot water system, a 5 star Gas Storage hot water heater system does not require any electricity to run its computing and standby functions.
Both the 5 star Gas Storage hot water heater system and Gas Continuous Flow/Instantaneous hot water systems have lower carbon footprints than some electric boosted solar hot water heater. The Gas Continuous Flow/Instantaneous hot water system will use 5 -10% less gas than a 5 star Gas Storage hot water heater system. However, a Gas Continuous Flow/Instantaneous hot water system requires electricity.
This is my biggest personal gripe with the gas instantaneous units. The Continuous Flow hot water system has minimum flow requirements before it will start heating water. Some units range between 2 and 3L/minute. This often leads to people doing this such a removing flow restrictors in order to get hot water sooner.
As a result of this, The Gas Continuous Flow/Instantaneous hot water system will lose between 15,000 litres and 20,000 litres of cold water down the drain every year. The 5 star Gas Storage hot water heater system will lose up to 2000 litres of water through its relief valve every year. This water is wasted if is not collected for the gardens.
Size and Location
As most people know, a Continuous Flow/Instantaneous hot water system takes up less room than a 5 star Gas Storage system and can be mounted high on the wall. Some models can also be installed inside, under the house or in the roof space. These units are a lot more expensive than the outside version.
Whilst a Gas Continuous Flow/Instantaneous hot water system can pump out endless hot water, it is limited by maximum and minimum flow rates. For instance a 26 litre per minute Gas Continuous Flow/Instantaneous hot water system running at 26 litres per minute will only raise the temperature of the water 35°C. If you attempt to use less than 2-3 litres per minute you will have no hot water.
A 5 star 135 litre tank will produce 330 litres of hot water at 60°C in the first hour. This is ample considering that each 10 minute shower will use 50 - 60 litres of hot water. Some showers are restricted to 25 -30 litre per 10 minute shower.
Also, a gas storage hot water system doesn't have minimum and maximum flow rates. If you it runs out, it will fully recover within 45 minutes!
On average the cost of the hot water heaters themselves are about the same. However, if all of the gas fitting, electrical and plumbing work is carried out by suitably licensed tradespeople then the cost to install a Gas Continuous Flow/Instantaneous hot water system is likely to be at least a few hundred dollars more expensive than a 5 star Gas Storage hot water heater system.
A Gas Continuous Flow/Instantaneous hot water system requires 5 times the volume of gas as a 5 star Gas Storage hot water heater system when it is operating. Therefore you will need to run a larger and more expensive gas pipe to supply the additional gas.
A Gas Continuous Flow/Instantaneous hot water system requires electricity for its computing functions and standby mode. Therefore you will have to pay a licensed electrician to supply and install an external power point. Costs also change depending on whether you are moving from an internal hot water heater to an external hot water system installation.
Both systems are proven to be equally reliable with manufacturers offering warranties up to 10 years.
Both the Gas Continuous Flow/Instantaneous hot water system and 5 star Gas Storage hot water heater system have a number of inbuilt safety features. Both can deliver tempered hot water to prevent hot water scalds. Both can have the water temperature controlled by touch pads. However, this is not very common in the gas storage hot water system.
You may find that the water temperature will vary more on a Gas Continuous Flow/Instantaneous hot water system if you use water efficient shower roses. This may also occur if you only want a small flow of water from the hot tap.
If you have any questions or would like to chat about any of this, please don't hesitate to give me a call on 0409461353.
“To waste, to destroy our natural resources, to skin and exhaust the land instead of using it so as to increase its usefulness, will result in undermining in the days of our children the very prosperity which we ought by right to hand down to them amplified and developed.”