Tankless water heaters have many advantages over tanked or storage-type units. One primary advantage is their ability to produce a continuous flow of heated water without running out.
Their life span is around three times as long as a storage water heater. And they don’t waste energy keeping water heated when you don’t need it. Though they are efficient, tankless water heaters have limitations.
Hot water demands
Imagine a Saturday morning when one family member is showering upstairs, another downstairs and the washing machine is running simultaneously. This stretches hot water demands. It can also stretch the flow rate of a single tankless water heater. These units heat water to a set temperature based on a flow rate. If all three activities demand 7 gallons per minute at 120 degrees, and your tankless water heater has a flow rate limit of 5 gallons per minute, the showers will be disappointing. Enough water will flow through but the temperature will be reduced.
Will two be better than one?
Once deciding to use tankless water heaters, many homeowners opt for more than one unit to avoid flow rate and temperature rise problems. Tankless water heaters use either electricity or gas. The gas varieties have a greater flow rate, 5 gallons per minute, than the electric type, 2 gallons per minute.
Faucets and showers farthest away from the water heater can present a problem as well. The water temperature may degrade several degrees before reaching distant outlets. Using several smaller units is often the optimal choice for ensuring peak efficiency, as well as flow rate and temperature rise.
Determining the best options
When deciding to purchase a tankless heater, the homeowner and installer should determine peak demand. Often two or more systems will be needed to meet the demand. You may want to use one for appliances and one for bathrooms. Or, you may choose to locate one nearer to the most distant hot water outlets. Either way, make sure you’re set for plenty of hot water during peak usage.
If you want more information about tankless water heaters, contact our staff at Rodenhiser Plumbing, Heating & Air Conditioning. Serving the Route 495/128 area, we’ll be happy to explain all the details and suggest the best options for your home.
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 Solutions Guide.
Hot shower image via Shutterstock