- 1 A Buyer’s Guide to Hot Water Systems
- 1.1 The pros and cons of the different hot water systems
- 1.2 Gas Hot Water Systems
- 1.3 Electric Hot Water Systems
- 1.4 Solar Hot Water Systems
- 1.5 Heat Pump Hot Water Systems
- 1.6 Storage tank or instantaneous?
- 1.7 The size of the household matters
- 1.8 Energy efficiency star ratings
A Buyer’s Guide to Hot Water Systems
It’s a wise homeowner who acts first rather than waiting until the hot water system quietly draws its last breath or goes out with a bang and leaves the family to suffer cold showers while a new one is quickly installed. This usually happens suddenly, always at the wrong time, and leaves you no time to shop around, not only for the best deal but for one that is energy efficient and will last longer and work better than the old one did. In this situation, many people would just replace same with same – set and forget – without doing some research on the best option. The following tips might help you make the right hot water system choices for your home and family.
The pros and cons of the different hot water systems
In a typical household, a quarter or more of the total energy used is taken up by heating water. So it’s a good idea to check how much energy your existing system uses, but be sure to do it before it stops working so you have time to shop around, as already mentioned. There are hot water systems that save money, energy and they are also more environmentally friendly than the older types. Remember though, the new regulations put in place to reduce energy consumption means that many homes can’t have new electric storage systems installed.
Gas, electric, solar or heat pump?
The heating method is the first thing you’ll need to consider when deciding on your new hot water system. Gas, electric, heat pump or solar?
Gas Hot Water Systems
A good choice is natural gas, providing you have the right connection. It’s a less expensive option than electricity, however, the price of gas is rising. Gas hot water systems heat water when it’s needed and since gas rates don’t change throughout the day they’re considered less expensive to run.
- A household consisting of four people will need a tank from 135–170L but there is also the option of an instantaneous hot water system.
- Although gas hot water units are usually placed outside the house because of the necessary ventilation, they can go inside if installed with a flue.
- They will have an energy star rating with regard to their energy efficiency.
Those with a pilot light will use gas, although only a small amount. It’s more economical if the one you choose has electrical ignition but the downside is in a blackout your hot water supply will be affected.
- An alternative to natural gas is Liquid Petroleum or LPG which comes in bottles, but they will cost you a lot more to run.
What do they cost? Gas hot water system prices are usually from around $900 to $2000, but this doesn’t include installation costs.
Electric Hot Water Systems
- Although they are rather expensive to run, (especially if they are on the full day rate) hot water system storage tanks heated with electricity are fairly inexpensive both to purchase and to install.
- If your electric system is off-peak it will be so much cheaper to operate, but because the water that’s heated overnight has to last all day, so you’ll need to have a large tank. Alas, not all homes can have off-peak electricity.
For a continuous full-day system a household of four usually needs a 125–160L tank or for off-peak, 250–315L.
- Electric hot water systems can be installed either inside or outside.
There are instantaneous electric hot water systems available.
What do they cost? They range in price from about $300 to $1500 (not including installation).
Solar Hot Water Systems
- The system will be made up of a storage tank and photovoltaic collector panels. If your family has four members you’ll most likely need about 4 sqm of solar collector area, which is two panels. The tank should be a 300–360L, and the reason it has to be large is to compensate for days of less sunlight, or if you have guests and the shower is used more than usual.
- You will also need a larger collection area if the panels can’t be placed in the best location on the roof to make the best use of the sunlight.
- On cloudy days when there isn’t enough sunshine the hot water system storage tank will need a gas or electric booster element to maintain the heat of the water.Due to the low
- operating costs, solar hot water systems pay for themselves over time, although they’re time-consuming and quite expensive to install.
- To help with the cost of buying and installing solar hot water systems, there are Government rebates and other incentives available.
What do they cost? They range from about $2000 to $7000 but that doesn’t include the installation costs.
Heat Pump Hot Water Systems
- Heat pumps extract heat from the air and use it to heat the water tank and as a form of electric storage tank system they are much more efficient. They work much the same way as an air conditioner or refrigerator. The units usually consist of an integrated tank and compressor. They can also come in the split form which is a separate tank and compressor.
- They have to be installed in an area that is well ventilated. This means outdoors.
- The units usually have rather noisy compressors, similar to outdoor air conditioner units, so make sure you don’t have them installed close to a neighbour’s home.
- Heat pumps usually work best in temperate and warm areas. However, there are cold climate models available, and most will include a booster element for high demand or cold days.
- A household of four will likely require a 270–315L tank.
- To offset the cost of buying and installing heat pumps there are Government rebates and other incentives available.
What do they cost? Prices range from $2500 to $4000 but that doesn’t include installation.
Storage tank or instantaneous?
After you get your heating method decided upon, the next consideration is whether to opt for a hot water system with a tank or one that heats the water as you need it.
- You’ll find that tanks are part of most gas, electric, solar and heat pump hot water systems.
- Tanks manufactured from mild steel can corrode so they need to be maintained every few years – they are normally sold with five to 10-year warranties.
- A more expensive choice is stainless steel, but these tanks do usually last longer and require less maintenance. Although they are sold usually with a 10-year warranty, they still might need some seals and valves replaced over time.
- The quality of your water supply can often be the decider regarding the kind of hot water system tank you buy so check with your installer.
- Your installer will probably suggest the tank be placed in a sunny area or somewhere that’s insulated to lessen the chances of heat loss. Although tanks are insulated, they always lose some heat.
Instantaneous hot water system
- These are also known as continuous flow hot water systems and rather than storing it in a tank, they heat the water as it comes through the pipe so you only use what you need. You don’t really get instant hot water because it can take a few seconds for the heated water to flow through the pipe to the tap. This is especially so if the unit is a fair distance from the tap.
- There are electric instantaneous hot water systems but they usually come in gas models.
- Instantaneous or continuous flow hot water systems are often much cheaper to operate than tank storage because there is no loss of heat.
- While running an electric instantaneous system is cheaper, it will use the full tariff when you use it, making the costs higher than off-peak but less than using a tank.
- Depending on the number of hot taps the heater has to serve (the rate of flow in litres a minute), generally, you will require a flow rate of about 22–24 L/min for a two-bathroom house. Ask your plumber or supplier to work out the best capacity for your home.
- You should confirm the trigger point requirements for your instantaneous hot water system because some people have found that theirs isn’t switching on because their showerheads are low flow and there is too high a trigger point. The problem is the showerhead doesn’t generate enough flow for the system to be triggered to heat the water.
The size of the household matters
It’s normally the case that one person will use around 50L of hot water per day and more if they often use the dishwasher and washing machine and use hot water. Then there’s the long hot shower taken often. A hot water system supplier or plumber can analyse your home and work out how much water you use and recommend some choices. Get quotes from at least two plumbers or suppliers and make sure they know about your hot water usage and the size of the family. A solar hot water system can be cost-effective and proficient to run.
To give you a better idea, here are some suggestions:
- For a small household of one to two people, you need an instantaneous flow hot water system, either electric or gas, or small gas storage.
- For a medium sized household of three to four people, you will need a gas system, either instantaneous flow or storage, or a heat pump system.
- For a large household of five plus people, you would need multiple instantaneous flow hot water systems, but gas storage units might be a better economic choice. A large heat pump can work as well.
Energy efficiency star ratings
This scheme is voluntary, not government regulated and gives gas hot water systems an energy efficiency rating by the number of stars that appear in a label on your unit. The more stars (up to 6) the better and the more efficiently the unit uses energy. Electric hot water storage systems are rated by Minimum Energy Performance Standards and ratings are now being considered for other water heater varieties. The aim is to eliminate from the market those models that are energy inefficient and to bring in the ratings on all hot water systems.