With cost of utilities set to increase this year again, being efficient with energy use is always top of mind. One of the ways you could save on your energy bills is by going the tank less hot water heater route. Just to clarify, the traditional way to supply hot water is by using a tank type system, where the water (40 gallons and up) is heated in a reserve tank that is available anytime. A tank less system on the other hand heats up water on demand (there are some hybrid models as well).
There are multiple factors to look at when deciding on this upgrade. We will discuss the two crucial ones below:
Flow GPM(gallons per minute)
What is this? This is the amount of water that is being used. To calculate how much water a fixture is using, take a measuring cup and measure how much water you have filled up in one minute. This will translate in the desired GPM (Gallons per minute). The following is typical usage per application:
Typical shower: 1.5 to 2.0 GPM
Typical bath faucet: 2.0 to 3.0 GPM
Bathroom vanity sink faucet: 0.5 to 1.5 GPM
Kitchen sink faucet; 1.0 to 2.2 GPM
Clothes washer: 1.5 to 3.0 GPM
For a comparison basis, a with a typical shower of 2.0 GPM, a 40 gallon tank from a tank type system will have water available for 20 minutes ( a very long shower). Given that most households have dishwashers, laundry, and multiple bathrooms, at least a 3.5 GPM or higher heater would be recommended.
What is this? This is the difference between the temperature of the water coming into the house (supplied by the city) and the temperature of the hot water required.
Why is this important? The flow rate of tank less water heater systems depend on temperature rise. All manufacturers will supply this information.
For example (and the eyes are starting to glaze over) : Given the desired temperature is 110 degrees Fahrenheit in a case where the water temperature from the city is 75 degrees, the temperature rise is 35 degrees. Let’s say at this temperature rise a given tank less system delivers 7 GPM. If the water temperature from the city is 35 degrees Fahrenheit, the temperature rise will be 75. At this rise, the same system might only deliver 4 GPM. This is a very important concept when choosing a system.
As with anything that will save money, the upfront costs are higher (why should the homeowner pocket the savings instead of the manufacturer). But the fact remains, energy prices are going to increase over time and investing in an energy efficient system should reduce the operating cost of the home.