Whether you’re in need of a new water heater now or you’re looking to switch over to a tankless water heater for other reasons, choosing the right size is essential. You don’t want to waste money on a larger unit than you need or throw money away on a tankless water heater that isn’t going to meet your needs. Installing the correct size tank will also help save you save money by reducing your energy bills.
Unlike traditional water heaters, tankless systems heat water on demand and are sized according to their ability to heat a specified number of gallons per minute rather than total holding capacity. To determine the size needed, calculate the flow rate of the hot water devices that will be used at once.
The flow rate is the number of gallons per minute that flows from the faucet. Check with the manufacturer for specific flow rates or use these average flow rates to calculate the total.
- Dishwasher – 3.0 GPM
- Washing Machine – 2.5 GPM
- Bathtub – 4.0 GPM
- Shower – 2.5 GPM
- Kitchen Sink – 2.0 GPM
- Bathroom Sink – 1.5 GPM
- Hot Tub/Jacuzzi – 6.0 GPM
Your water heater needs to be capable of handing the necessary flow rate. For example, if you are using the dishwasher and shower at the same time, add the flow rate of these together for a combined total of 5.5 gallons per minute. You will need a 5.5 GPM tankless water heater or larger.
Temperature and climate should also be considered when determining the size of on-demand water heater you need. In colder climates or during the winter months, the water heater’s ability to heat may be reduced by 2 to 4 gallons per minute when compared to hot weather climates or summer months. You may want to factor in a couple extra gallons to compensate for the difference and make sure you have enough hot water year round.
For more information on choosing the right tankless water heater, or to explore other options, contact us. Around the Clock Air Conditioning and Heating, Inc. is here to help with all your heating, cooling and indoor air quality needs.
Our goal is to help educate our customers in Los Angeles, North Hollywood and surrounding areas about energy and home comfort issues (specific to HVAC systems). For more information about tankless water heaters and other HVAC topics, download our free Home Comfort Resource guide.
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