Choosing the right size of tankless water heater to meet your specific needs is one of the most important (and often most neglected and misunderstood) steps in purchasing a tankless water heater.
Here are some parameters you need to evaluate carefully prior to shopping and installing your Titan tankless water heater:
1. Peak hot water demand (how much hot water will you need delivered if all your hot water users were to run simultaneously)
2. Desired temperature rise (how hot you want the water to be delivered)
3. Real Estate (find the right spot for your heater to eliminate extra pipping)
To size a tankless water heater, you need to determine the flow rate and the temperature rise you'll need for its application (whole house or a remote application, such as just a bathroom) in your home.
First, list the number of hot water devices you expect to use at any one time. Then, add up their flow rates (gallons per minute). This is the desired flow rate you'll want for the demand water heater. Here are some numbers from the U.S.Department of Energy: For example, let's say you expect to simultaneously run a hot water faucet with a flow rate of 0.75 gallons (2.84 liters) per minute and a shower head with a flow rate of 2.5 gallons (9.46 liters) per minute. The flow rate through the demand water heater would need to be at least 3.25 gallons (12.3 liters) per minute. To reduce flow rates, install low-flow water fixtures.
To determine temperature rise, subtract the incoming water temperature from the desired output temperature. Unless you know otherwise, assume that the incoming water temperature is 50F (10C). For most uses, you'll want your water heated to 120F (49C). In this example, you'd need a demand water heater that produces a temperature rise of 70F (39C) for most uses. For dishwashers without internal heaters and other such applications, you might want your water heated at 140F (60C). In that case, you'll need a temperature rise of 90F.
Here is a handy sheet to calculate power needed for certain temperatures and flow rates: From our experience, here are our recommendations:
APPLICATION
MODELS
Houses
N-120, N-100
Apartments
N-1OO, N-85
Efficiencies
N-85, N-75
Point of Use
N-64, N-10
N-10 uses 110 volts and will supply only warm water. In areas with cold weather, always use the highest model.
