1. Hot Water Recirculation
One of the advantages of a tankless water heater is endless hot water. But, if your tankless water heater does not have a recirculation system, hot water will sit in the pipes and cool off between uses. This is why most traditional tankless water heaters have a "wait" time for the water to heat up when you turn on a fixture. The best solution to have endless hot water delivered fast is to get a tankless water heater with Recirculation.
Rinnai offers a few different recirculation solutions for homeowners who want instant access to hot water. Some of their units come with an integrated pump that recirculates water back to the tankless water heater so hot water is always available in every part of your home. However, this requires a dedicated return line which can be costly to install if your home doesn't have one available.
Fortunately, Rinnai offers a cost-friendly recirculation solution for homes without a dedicated return line. It is called ThermaCirca360 technology. This is available in their SE+ series of tankless water heaters that use a thermal bypass valve which will temporarily use your cold water line for recirculation. Rinnai's technology also provides homeowners with the option to set recirculation schedules based on peak-usage or through the use of installed motion sensors. With a recirculation system, you will have instant access to endless hot water throughout your home regardless of usage.
2. Flow Rate ( gallons per minute GPM)
Flow rate, or gallons per minute (GPM), is the measure of how many gallons of water flow out of a fixture each minute. It’s important to take inventory of the fixtures in your home that use hot water so you can determine the size of a tankless water heater necessary to satisfy your home's hot water needs. In general, you will want to buy a tankless water heater with a flow rate that is larger than the GPM your home uses during peak-usage times.
Below is a list of the average flow rates of typical fixtures found in the home:
- shower: 1.5 GPM to 3.0 GPM
- kitchen faucet: 2 to 3 GPM
- bathroom sink: 0.5 to 1 GPM
- washing machine: 2 to 3 GPM
- bathtub: 4 to 6 GPM
- dishwasher: 1 to 2 GPM
To calculate your peak hot water demand, add together the GPM of every fixture that requires hot water at the same time. Compare that number to the flow rating of the tankless water heater that you plan to buy.
More important than flow rate is the power, or BTU rating, of your tankless water heater. The goal is to get access to endless hot water, so it’s necessary to source a tankless water heater with a thermal capacity high enough to fulfill the hot water demands of your household. BTU, or British Thermal Unit, is the measurement of how much energy is needed to raise the temperature of water by 1 degree Fahrenheit.
A common mistake people make is forgetting about the temperature of groundwater entering the home when deciding how powerful their tankless water heater needs to be. Typically, groundwater in northern states is colder than groundwater in southern states.
If you live in Minnesota, the groundwater averages 40 degrees Fahrenheit, so you will need to purchase a tankless water heater with a BTU rating sufficient enough to raise the groundwater temperature 80 degrees in order to arrive at an acceptable average hot water temperature of 120 degrees.
Have more questions on what features you should have on your tankless water heater? Contact us here, and one of our water heater experts can walk you through your options.