Continuous Flow/Instantaneous hot water systems – are they better than Gas storage hot water systems?
Firstly, At 6 Star Hot Water & Plumbing we take pride in giving our customers informed advice. I have been selling, supplying and installing gas, electric and solar hot water heaters for 25 years. I am also one of just a handful of plumbers who have attended Australia’s only hot water Institute. Therefore, we can guarantee you that our advice is based on experience and ongoing professional development.
How to choose a hot water heater
When buying a hot water heater your choice will be based on a number of reasons specific to you. These will be energy efficiency, environmental impact, the size of the hot water system and its location, amount of available hot water, installation costs, reliability, serviceability and safety. We will compare these issues one by one
Over a year, 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. However, a 5 star Gas Storage hot water heater system does not require any electricity to run its computing and standby functions as does a Gas Continuous Flow/Instantaneous hot water system.
Further, according to a paper delivered by Adjunct 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.
The best way to determine how efficient the hot water heater will be is to ask the sales person to tell you the average yearly gas consumption of the various units they are selling to you. Don’t forget that a Gas Continuous Flow/Instantaneous hot water system also uses electricity which is not included on the gas consumption data plate.
This can be broken into two categories
Both the 5 star Gas Storage hot water heater system and Gas Continuous Flow/Instantaneous hot water system 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.
The Gas Continuous Flow/Instantaneous hot water system has minimum flow requirements before it will start heating water. Some units range between 2 and 3L/minute. We have found that some of the more water efficient shower roses have to be changed or their restrictors removed so that the Gas Continuous Flow/Instantaneous hot water system will produce hot water. The minimum flow rates of a Gas Continuous Flow/Instantaneous hot water system means that you cannot be economical with water whilst doing things like shaving and rinsing dishes.
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.
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. This does not take into account the longer shower that also might be had.
You can learn more if you visit the websites listed below.
Size and Location
If space was the main factor I would chose the Gas Continuous Flow/Instantaneous hot water system.
A Gas Continuous Flow/Instantaneous hot water system takes up less room than a 5 star Gas Storage hot water heater 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 generally twice the price of an external Gas Continuous Flow/Instantaneous hot water system
Always try to locate your hot water system close to the most frequently used tap. Normally this is the kitchen. This tap will generally get used 5 times more frequently than any other hot tap in your hose. By putting it close to the most frequently used tap you reduce water wastage and heat loss.
Amount of available hot water
It is important to select a hot water system that matches your hot water needs.
A Gas Continuous Flow/Instantaneous hot water system can go on producing endless hot water. However, 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.
Additionally, a 5 star storage hot water ssytem is not limited by minimum and maximum flow rates. If you manage to run the 5 star Gas Storage hot water heater system out it will fully recover within 45 minutes, producing piping hot water again.
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.
The majority of Gas Continuous Flow/Instantaneous hot water systems are very reliable. You could expect a life of 10-15 years. The majority of 5 star Gas Storage hot water heater system systems are very reliable and very durable. In Canberra we have replaced systems that are 22 years old. These systems were built with a 5 year tank warranty. You can buy a 5 star Gas Storage hot water heater system with ten year cylinder warranty.
The 5 star Gas Storage hot water heater system systems can easily be serviced by a licensed gasfitter. Most of the parts are interchangeable with other brands. You could expect same day repairs if you had a problem with your 5 star Gas Storage hot water heater system.
The Gas Continuous Flow/Instantaneous hot water system is a very complicated piece of plumbing and electronics. There are not many people in Canberra who can fix them. Therefore, you are likely to have to wait 2-3 days for repairs.
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. Importantly, 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 on a 5 star Gas Storage hot water heater system.
You may find that the water temperature will jump up and down dramatically 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.
Some Gas Continuous Flow/Instantaneous hot water system models can be turned up above 70°C. This can be dangerous if someone is using very hot water in the kitchen and another person goes to use a shower expecting it to be no hotter than 50°C. The only method of avoiding this is to remove the touch pad controllers and installing a tempering valve on the bathroom hot pipes.
It is recommended that a tempering valve be fitted to a 5 star Gas Storage hot water heater system where the pipes go to ablution areas. However, in some cases it is possible to run an untempered line to the kitchen and laundry. Therefore, you can have 50°C water at the shower while someone in the kitchen is using water at 70+°C.
What is different about Canberra water
Rain water, like Canberra water, is unique as it contains little mineralisation. Therefore our storage hot water tanks last longer than they do in many other places. In my 25 years of servicing hot water heaters in Canberra I have never had to replace a sacrificial anode. As I said previously, I have replaced gas and electric storage tanks that are 22 years old and were originally sold with a 5 year warranty.
Finally, 6 Star Hot Water & Plumbing will do its best and give you its best price when it supplies and installs any type of hot water system you want.
If you need more information about your gas hot water or immediate help in Canberra, Queanbeyan or Jerrabomberra just call 6161 9417 for Six Star Hot Water & Plumbing.