A tankless water heater can be an attractive alternative to a conventional storage water heater. Instead of storing hot water in a large tank, a tankless water heater provides hot water on demand, using gas or electricity. While traditional systems rely on fixed hot water tank sizes, tankless units eliminate the need for storage by heating water only when needed. The most popular gas-fired model is the “demand” type, while the most popular electric models are called “instantaneous” or “tankless on-demand.”
Tankless water heaters last longer than storage models and have no standby loss (electric models) or fuel loss (gas models). Some models can save you as much as 50% GPM off your monthly utility bill. However, they’re more expensive initially than conventional storage models, and they’re most likely too small to supply all of your hot-water needs. They’re also more complicated to install. Compared to systems with traditional hot water tank sizes, tankless systems require a more calculated approach to installation and water flow expectations. If you use only a few gallons of hot water at a time, it may not be worth the investment.
One of the most common questions we receive is how to determine the correct size tankless water heater for your home. This is an important question because a tankless water heater will cost you thousands of dollars to purchase and install, and if you get the size wrong, you could end up with a unit that doesn’t meet your hot water needs. Understanding your household usage patterns and comparing them against standard hot water tank sizes can help inform your decision.
When choosing between tankless units and conventional models, always consider factors like daily usage, flow rates, and existing hot water tank sizes. In many cases, assessing your past system’s hot water tank sizes gives a strong starting point to gauge what your tankless replacement should handle.
What you need to know when choosing a tankless water heater:
Size: One of the biggest decisions in choosing a tankless is how big you want to go. Manufacturers typically offer units that provide anywhere from .5 GPM to 6 GPM of hot-water flow for every 1,000 square feet of living space.
As an example, let’s say you are a typical family of four living in a three-bedroom home. You have two teenage children, who take long showers every morning and have friends over on weekends. During peak times, you need five gallons of hot water per minute. Your average daily usage is 70 gallons per day, and there are four people in your household. Here’s how to calculate the right size for you:
Peak time usage: 5 GPM x 4 hours (2 teenagers taking showers) = 20 gallons per day
Average daily usage: 70 gallons/day x 4 people = 280 gallons/day
Required size: 280 gallons per day / 70 gallons per day minimum requirement = 4
Flow Rates
A flow rate is typically measured in gallons per minute (GPM). The flow rate of a low-flow showerhead is 2.5 GPM and a high-flow head is 5 GPM or higher. Most homes have an average of 2.5-5 GPM fixtures but it’s important to know what you have because it will affect the size of the tankless water heater that you should choose.
Flow Rates for Various Fixtures are their typical Flow Rate is:
- Shower 2.5 gallons per minute (GPM)
- Hand Shower 1.5 GPM
- Bathtub 2.0 GPM
- Kitchen Sink 2.0 GPM
- Dishwasher 2.0 GPM
- Laundry Tub/Appliance 3.0 GPM
- Washing Machine 4.0-6.0 GPM
Other Sizing Notes
In general, it is best to locate the tank near the point of use. However, hot water tank sizes must be carefully considered if several fixtures are located on a long pipe run or if there are significant elevation changes in the plumbing system. Additional pressure drops can impact performance, so choosing the right hot water tank sizes helps ensure consistent flow and temperature. You may need to install back-pressure valves to maintain adequate flow rates, especially in larger systems where hot water tank sizes play a major role in balancing supply across multiple fixtures.
If your home includes various fixture types (such as faucets with aerators), ensure that all can be supported by your chosen tankless unit, and that your selected hot water tank sizes are suitable for household demands.
Hot water tank sizes also affect tubing requirements. Tubing refers to the length of copper pipe between the tankless heater and your fixtures. If you’re switching from a traditional system, you’ll need to ensure existing hot water lines are long enough—or adaptable—for your chosen hot water tank sizes and layout. As a rule of thumb, if there’s less than 25 feet between the heater and fixture, you’re good. But remember: every extra foot of tubing can reduce the flow rate by half a gallon.
6 Signs Your Water Heater is About to Fail
Water heaters are the heart of the home. Despite their importance, most people don’t think about them until there’s a problem. You may be surprised to know that water heaters typically have a life expectancy of 8-15 years.
Contact our professional hot water system repair team today to avoid major issues within your hot water system in Australia.
While it’s important to have your water heater inspected annually, there are also a number of signs you can look out for that will help you avoid a water heater failure, and possibly an emergency situation.
The average lifespan of a water heater is about 10 to 12 years, though some make it up to 20 years. The best way to know when your water heater is getting old is to monitor it regularly. Here are 6 signs that it’s probably time to replace your water heater. If you notice any of these signs that your water heater is likely about to fail and you should contact us today!
1. Taps or Knocking Sounds
If your water heater has been making strange noises, chances are it’s on its last leg. This can be caused by sediment collecting at the bottom of the tank. Sediment buildup is common in water heaters that are over 10 years old and should prompt you to consider a replacement. When this happens, the tank needs to be flushed out before repair or replacement can occur. Other potential problems include a faulty pressure relief valve and a malfunctioning heat exchanger.
2. Not Enough Hot Water
If your hot water isn’t as hot as it used to be, this could be your first sign that something is wrong with your unit. Older units can experience reductions in hot water output due to sediment buildup or corrosion of the heating element. You may also experience a lack of hot water if the tank is damaged or if the thermostat is faulty. An experienced plumber or gas fitter should be able to fix this problem or advise if it needs replacing.
3. Temperature Fluctuations:
If you notice your water temperature varies greatly throughout the day, this could be a sign that your heater is failing. The fluctuation in temperature will depend on how old your particular model of the heater is. Newer models can have temperature fluctuations within degrees while older models have temperature fluctuations within ranges up to 30 degrees celsius.
4. Leaks
Leaks could indicate a major problem with your water heater. Leaks are usually caused by corrosion around pipes and fittings, broken seals or worn-out gaskets. A good plumber will be able to find the source of your leak and fix it up for you before it becomes irreparable.
5. Cloudy or Odd-Smelling Water
Cloudy or odd-smelling water is often a warning sign of a hot water system not working properly. Typically, bacteria growth caused by organic matter in the tank can lead to unpleasant odours and metallic-tasting water. If your hot water system is not working as it should, sediment buildup could be to blame, affecting both the taste and safety of your water. In some cases, cloudiness may indicate lime or scale accumulation, another common reason for a hot water system not working efficiently. Whatever the cause, it’s important to get in touch with a licensed plumber promptly. Leaving a hot water system not working unchecked can result in more serious damage and costly repairs down the line.
Things to Consider When Replacing Your Water Heater
Replacing your water heater seems like a pretty straightforward project, but it’s actually a lot more complicated than you might think. You need to consider how old your current unit is, what type of water heater you want to install, and what hot water tank sizes best suit your household’s needs. Choosing the wrong size can lead to inefficiency and increased energy bills. This decision can be daunting—especially if you haven’t replaced your water heater before or are unfamiliar with the range of hot water tank sizes available. If you’re in this situation, give Anytime Hot Water a call—we can help you choose the right system and size for your home.
What do I need to know before replacing my water heater?
To make an informed decision, you need to know how much it will cost to replace your water heater and what you’ll get for your money. Here are some other important things to consider when replacing your water heater:
Size: One of the most common mistakes people make when replacing their water heater is purchasing one that’s too small for their household needs. While smaller hot water tank sizes may seem more cost-effective upfront, they often fall short of meeting daily demands. It’s tempting to choose the cheapest, most compact option, but selecting the right size is critical for long-term satisfaction.
Your future needs: It’s also essential to think ahead. If you’re planning a home extension or adding extra bathrooms, you’ll need to consider larger hot water tank sizes that can accommodate increased usage. Choosing the right system now saves you from costly upgrades later.
Energy Efficiency: Another vital consideration when replacing an old water heater is energy efficiency. New models—whether gas or electric—offer better insulation and smart circuit boards for more precise temperature control. Opting for units with condensing technology can save even more on your utility bills. Matching energy efficiency with appropriate hot water tank sizes ensures your system runs optimally.
Tubing and fittings: Before buying a water heater, calculate the length of tubing required to connect it to your plumbing. You’ll also need fittings like elbows and tees. Complex plumbing runs may require additional parts, which should be planned alongside choosing from available hot water tank sizes.
Warranty: Most water heaters come with limited warranties, usually covering labour costs for the first year. Check the duration and extent of coverage to ensure you’re protected.
Insulation: Some modern water heaters come with insulation kits that can reduce energy loss and condensation by up to 30%. It’s usually worth investing a little more for these energy-saving features, especially when combined with correctly sized hot water tank sizes that prevent overuse and inefficiency.
Frequently Asked Questions:
Q: What factors should be considered when choosing a tankless water heater size?
A: Household size, number of simultaneous users, and flow rate requirements.
Q: How does household water usage impact the selection of tankless water heaters?
A: More users or fixtures increase demand, requiring a higher GPM (gallons per minute) rating.
Q: Are there specific sizing guidelines for tankless water heaters?
A: Yes, typically based on peak water usage during mornings or evenings.
Q: How can I ensure optimal performance with the right-sized water heater?
A: Choose a model that matches your demand and ensure proper professional installation.
