What Size Tankless Water Heater Do I Need For My Home?

Water tankless heaters are one of the best-selling home appliances in the market today. This is attributed to the many versatile features and factors associated with tankless water heaters. These are automatic devices that are used to supply hot water to your home at any time or whenever needed. Beginning with a continuous and reliable supply of hot water, low operation and maintenance cost, energy-efficient, space-saving, easy installation, durability, among others, are some of the tankless water heater features.

Tankless water heaters are designed for both commercial and residential use, hence very popular. Generally, tankless water heaters are designed to continuously steam water as the heater supplies water to different taps in your household. This article will provide you with some of the information on the frequently asked questions about tankless water heaters.

What is the Right Size of a Tankless Water Heater Do I Need for My Home?

There are so many versatile tankless heaters in the market today, but choosing the right size of the tankless water heater determines how well the heater will serve you. To know the best size for your home, you need to consider the following factors.

– The size of your house.

There are so many different sizes of tankless water heaters, designed for different house sizes. The best size should sufficiently supply your home with hot water regardless of the number of taps in your house. Choosing smaller sizes will lead to insufficient hot water supply or restricted water supply to some taps only.

– Your house water flow rate.

Due to the working mechanism of a tankless water heater, the output water flow rate of your taps is determined by the rate of water supply by the heater. So the number of your taps, as well as their flow rate, also helps in determining the size of the heater. The water flow rate of the heater should be more than or just equivalent to the total flow rate of all your taps.

  • Original Design: Tankless hot water heater's Circ-Logic technology offers recirculation patterns that match your habits; For the latest in non-condensing technology that speeds up service and installation, check out our new RE180iN model
  • Never Run Out of Hot Water with this Compact Tankless Gas Water Heater: Non-condensing tankless hot water heater from Rinnai is only the size of a small suitcase and fits in a wide variety of spaces, but provides up to 9.8 GPM (6 fixtures at once)
  • Smart, Durable Design: Includes 12-, 5-, and 1-year residential guarantee and 5-, 5-, and 1-year commercial factory warranty for heat exchanger, labor, and parts, respectively; See Controlr module for WiFi control (not included)
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Find Your Rinnai: See our product guides, manuals, energy guide, warranty information, videos, and tables to find the right tankless water heater for your home; Check our Ground Water Temperature Map to see if this heater is optimal for your region

– Temperature rise.

Temperature rise is the difference between the required output water temperature and the incoming water temperature. The temperature rise helps in determining both the size of the heater as well as the heater power. The temperature rise is determined after determining the total water flow rate in all your house faucets, and this helps in determining the required heater power to heat up the water to the required temperature rise while maintaining a constant flow rate.

  • Whole home indoor, gas powered tankless water heater, rated at 3 GPM that activates only on demand and no pilot light needed, reducing energy consumption
  • Sleek, modern design with black tempered glass front panel featuring an easy to use LED display controls
  • Features fully automatic temperature controls with an energy saving mode and child lock technology
  • Safe electronic ignition system; Plugs into standard 110v electrical outlet with UL-listed cord. Field tested to 5500 ft. elevation (not recommended to be used any higher)
  • Uses standard 1/2" NPT water fittings and comes with horizontal venting allowing for a convenient and quick installation

Can a Tankless Water Heater Work for the Whole House?

Yes, a tankless water heater can be used to supply water to the whole house, whether small or large houses. The intended purpose for a tankless water heater determines the power output of the heater. Heaters designed for very large houses with high water consumption are designed with high power and high flow rate, to continuously supply water hot water as needed.

Although, these powerful heaters have a higher operation cost. Generally, the key factor to consider for a whole house or large house tankless water heater is the heater power and rather not the flow rate. Some of these heaters are designed with a high flow rate but with small power, hence not capable of sufficiently supplying water throughout the whole house.

Recommended Large Power Natural Gas Tankless Water Heaters For Whole House Use

  • Original Design: Tankless hot water heater only heats when necessary to conserve energy; For the latest in non-condensing technology and a cleaner layout that speeds up service and installation, check out our new RE160eN model
  • Never Run Out of Hot Water with this Compact Tankless Gas Water Heater: Non-condensing tankless hot water heater from Rinnai is only the size of a small suitcase and fits in a wide variety of spaces, but provides up to 6.5 GPM (5 fixtures at once)
  • Smart, Durable Design: Enhanced scale detection helps prevent serious, long-term damage to unit; Includes 15-, 5-, and 1-year residential guarantee for heat exchanger, labor, and parts, respectively; See Controlr module for WiFi control (not included)
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Find Your Rinnai: See our product guides, manuals, energy guide, warranty information, videos, and tables to find the right tankless water heater for your home; Check our Ground Water Temperature Map to see if this heater is optimal for your region
  • Original Design: Tankless hot water heater only heats when necessary to conserve energy; For the latest in non-condensing technology and a cleaner layout that speeds up service and installation, check out our new RE160iN model
  • Never Run Out of Hot Water with this Compact Tankless Gas Water Heater: Non-condensing tankless hot water heater from Rinnai is only the size of a small suitcase and fits in a wide variety of spaces, but provides up to 6.5 GPM (5 fixtures at once)
  • Smart, Durable Design: Enhanced scale detection helps prevent serious, long-term damage to unit; Includes 15-, 5-, and 1-year residential guarantee for heat exchanger, labor, and parts, respectively; See Controlr module for WiFi control (not included)
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Find Your Rinnai: See our product guides, manuals, energy guide, warranty information, videos, and tables to find the right tankless water heater for your home; Check our Ground Water Temperature Map to see if this heater is optimal for your region
  • Endless Hot Water: Enjoy unlimited hot water flow throughout the house; compact, durable, and easy to install; professional installation recommended
  • Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary
  • Optimal Water Pressure: Up to 11 GPM hot water flow rate for a powerful, constant stream
  • Instant Heating: Equipped with Circ-Logic - Pair with an external pump to reduce wait time for hot water via scheduled or on-demand recirculation
  • Guaranteed to Last: 15-, 5-, and 1-year residential for heat exchanger, labor, and parts, respectively. Wifi monitoring.

What is the Right Size of a Tankless Water Heater Do I Need for a Family of 5?

Tankless water heaters work by supplying hot water continuously while heating up the water simultaneously, unlike the tank water heaters that work by heating up a certain capacity of water and then supplying the hot water. Therefore, to determine the right size of the tankless water heater for your family, it is important to consider the flow rate rather than the storage capacity.

Determining the flow rate involves counting the number of fixtures in your home that will run simultaneously. For a family of five, with 3 to 5 bathrooms and a number of sink faucets as well as laundry taps, an ideal heater should have a flow rate equal to all the faucets running at the same time. This is obtained by adding the total flow rate of these faucets. Generally, for a family of five members, an ideal tankless heater should have a total flow rate of 9 GPM with up to three showers.

Recommended Tankless Water Heater For Family of 5

  • Original Design: Tankless hot water heater only heats when necessary to conserve energy; For the latest in non-condensing technology and a cleaner layout that speeds up service and installation, check out our new RE160eN model
  • Never Run Out of Hot Water with this Compact Tankless Gas Water Heater: Non-condensing tankless hot water heater from Rinnai is only the size of a small suitcase and fits in a wide variety of spaces, but provides up to 6.5 GPM (5 fixtures at once)
  • Smart, Durable Design: Enhanced scale detection helps prevent serious, long-term damage to unit; Includes 15-, 5-, and 1-year residential guarantee for heat exchanger, labor, and parts, respectively; See Controlr module for WiFi control (not included)
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Find Your Rinnai: See our product guides, manuals, energy guide, warranty information, videos, and tables to find the right tankless water heater for your home; Check our Ground Water Temperature Map to see if this heater is optimal for your region

Can You Run out of Hot Water with a Tankless Water Heater?

Unlike the tank water heaters where water is first heated constantly in the storage tank, tankless water heaters only heat up water when required and heat up water as it flows. Therefore, there is no single time you will ever run out of hot water. Also, tankless water heaters have a longer lifespan than the tank model, hence many years of hot water supply.

The only problem associated with tankless water heaters is insufficient water supply in cases of small unit installation for large houses. To ensure that you never run out of hot water, it is important to consider the right size of the tankless water heater in relation to the intended use.

What is the Right Size of a Tankless Water Heater Do I Need for a Family of 3?

To know the right size of the tankless water heater for your family with three members, you should consider the number of faucets in your home, and then considering the number of fixtures that will run at the same time. After this, then determine the flow rate of each fixture to get the total flow rate that will be required at the same time.

Usually, there is a general flow rate range for most fixtures that can help you determine the total flow rate that you require depending on your family uses. For instance, a family of three with two showers, a kitchen sink, and a dishwasher, 6 GPM is an ideal flow rate.

Recommended Tankless Water Heater for Family of 3

  • Endless on-Demand Hot Water; Consistent hot water when you need it that never runs out; Continuously monitored water temperature and controlled flow rates ensure efficiency and consistent performance within 1 degree of selected temperature
  • Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank heaters; may be installed on wall or at point of use; Dimensions 17 x 17 x 3.75 inches 
  • Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only heats water when called unlike a tank heater that maintains water temperature even when not being used. Save up to 50% in water heating costs according to the Department of Energy
  • EcoSmart ECO 27 Sizing; Refer to the sizing map. Requires 3x40 AMP Double Pole Breaker, 27-kilowatt tankless electric water heater ideal for providing hot water for whole home applications; provides between 2.7 and 6.5 gallons-per-minute depending on the inlet water temperature; refer to the sizing guide to select the proper solution
  • Warranty and Certifications; Limited Lifetime Warranty on electronics, exchanger and element; UL-499 certified; ETL Listed
  • Required Breaker Quantity: Three 40 Amp Double Pole
  • Recommended Electrical Panel: 200 Amps
  • NEVER run out of hot water with an ECOSMART tankless water heater.
  • Save up to 12 cubic feet of storage space.
  • Digital temperature control in 1-degree increments gives users complete control of hot water

What is the Right Size of a Tankless Water Heater is Needed for a Family of 4?

The same case happens with a family of four. The number of taps and fixtures using the hot water from the tankless water heater determine the ideal size and flow rate of their tankless water heater. For instance, a family of four with 3 showers, kitchen, and other sinks can require 8 GPM or more depending on how many fixtures that run simultaneously.

Recommended Tankless Water Heater For Family of 4

  • External digital thermostatic control with LED display (+/1 degree accuracy)
  • Most advanced self-modulation, adjust power to meet hot water demand
  • Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM
  • Simple installation – bottom 3/4 inch NPT water connections
  • Threaded for easy replacement, simple installation, digital temperature display

Conclusion.

In conclusion, tankless water heaters are very versatile heaters designed for a constant and reliable supply of hot water. The above article has explained a number of points about the size of a tankless water heater.