Tankless water heaters can be a significant energy saver for homeowners because they don’t rely on a storage tank to keep water heated throughout the day. Conventional tank systems can be subject to significant standby losses, a factor that tankless systems bypass through their instantaneous ability to heat water. Before you purchase a system, be sure to take sizing factors into account.
In order for a tankless system to meet the hot water needs in your home — for washing clothes, showering and cleaning dishes for instance — sizing calculations must take into account temperature rise and flow rate.
To size a system, you need to evaluate the maximum usage for your hot water needs. This requires that you assess the number of devices you wish to use at peak capacity, and the most effective way to do so is to take into account the systems you use in the morning when most homeowners shower. If you have a tankless system for one bathroom, and you expect to use it for shower and sink use at the same time, you would factor the flow rate of the faucet at approximately 3 litres per minute and the shower at about 10 litres per minute. Therefore, you would need a flow rate of at least 13 litres per minute for that application.
It’s also necessary to factor in the system’s temperature rise, because water enters your home at a particular temperature, generally 10 degrees. Most homeowners desire the outgoing water temperature at a comfortable 49 degrees. Therefore, a minimum temperature rise should be 39 degrees.
When considering tankless systems, you have to think a little differently than you would for conventional systems. It’s often necessary for homeowners to install several tankless applications to meet all of a home’s hot water needs, with perhaps one larger system for household activities like washing clothes and dishes, and smaller systems installed at point of use locations, like bathrooms and the kitchen.
If you’d like to explore the energy-saving possibilities of tankless water heaters, contact the experts at Arpi’s Industries.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about water heaters and other HVAC topics, download our free Home Comfort Resource guide.