What Size Tankless Water Heater For 2 Bathrooms

When it comes to choosing a tankless water heater for a home with two bathrooms, it's essential to consider the specific needs and usage patterns of the household. Several factors influence the appropriate size of the unit, including the number of fixtures, the flow rate of the fixtures, and the desired temperature rise.

To determine the approximate size required, consider the following steps:

1. Estimate the Peak Demand: Determine the maximum number of fixtures that may be used simultaneously. For two bathrooms, this typically includes a shower, a sink, and a toilet in each bathroom. Assign a flow rate to each fixture based on its type and usage. For example, a standard showerhead typically has a flow rate of 2.5 gallons per minute (GPM), while a sink faucet may have a flow rate of 1.5 GPM.

2. Calculate the Total Flow Rate: Multiply the flow rate of each fixture by the number of fixtures that may be used simultaneously. For instance, if two showers and two sinks are likely to be used at the same time, the total flow rate would be: (2.5 GPM x 2) + (1.5 GPM x 2) = 8 GPM.

3. Determine the Temperature Rise: Calculate the temperature difference between the incoming cold water and the desired hot water temperature. For example, if the incoming water temperature is 55°F and the desired hot water temperature is 120°F, the temperature rise would be 65°F.

4. Calculate the BTU Rating: Use the formula BTU = (Flow Rate x Temperature Rise) x 0.83. In this example, the BTU rating would be: (8 GPM x 65°F) x 0.83 = 431.6 BTU/hr.

Based on the BTU rating calculated above, a tankless water heater with a capacity of approximately 7 GPM @ 65°F temperature rise or higher would be suitable for a home with two bathrooms. This size unit can provide sufficient hot water flow to meet the simultaneous demand from multiple fixtures without running out of hot water.

It's advisable to consider a slightly larger unit if there are additional factors to consider, such as high-flow fixtures, a large bathtub, or frequent use of hot water for extended periods. Conversely, a smaller unit may suffice if water-saving fixtures are installed, and hot water usage is relatively moderate.

When selecting a tankless water heater for two bathrooms, it's essential to consult with a qualified professional to ensure the unit is appropriately sized for the specific needs of the household. They can evaluate the factors discussed above and provide personalized recommendations to optimize hot water performance and efficiency.