#Peakhour windows how to#

Unless you know otherwise, assume that the incoming water temperature is 50✯ (10✬). To determine temperature rise, subtract the incoming water temperature from the desired output temperature. To reduce flow rates, install low-flow water fixtures.

The flow rate through the demand water heater should be at least 3.25 gallons (12.3 liters) per minute. If you don’t know the flow rate, estimate it by holding a pan or bucket under the faucet or shower head and measure the flow for a minute. For example, let's say you expect to simultaneously run a hot water faucet with a flow rate of 0.75 gallons (2.84 liters) per minute and a shower head with a flow rate of 2.5 gallons (9.46 liters) per minute. This is the desired flow rate you'll want for the demand water heater. Then, add up their flow rates (gallons per minute). Therefore, to size a demand water heater, you need to determine the flow rate and the temperature rise you'll need for its application (whole house or a remote application, such as just a bathroom) in your home.įirst, list the number of hot water devices you expect to use at any one time. Tankless or demand-type water heaters are rated by the maximum temperature rise possible at a given flow rate. Sizing Tankless or Demand-Type Water Heaters If you haven't yet considered what type of water heater might be best for your home, learn more about selecting a new water heater. Storage and heat pump (with tank) water heaters.įor sizing combination water and space heating systems - including some heat pump systems, and tankless coil and indirect water heaters - consult a qualified contractor.

#Peakhour windows how to#

Here you'll find information about how to size these systems: Therefore, before purchasing a water heater, make sure it's the correct size. A properly sized water heater will meet your household's hot water needs while operating more efficiently.