Tankless Buying Guide: What You Need
If you are leaning towards tankless, it is important to determine the hot water requirements of your home before you can start seriously examining units.
The amount of hot water will you need at peak demand... (let's say when somebody's showering, you're doing dishes, and there are clothes in the wash?)
Finding out hot water demand is very simple...
Make a list all of the fixtures that will be using hot water from the tankless heater, and also add-up their flow rates.
How can you detect the flow rate?
Once you buy the fixture, you have to check the documentation it came with or you can go online to find out more about it.
You are going to also need to determine the temperature of incoming water.
Although real temperatures will of course differ, this rough guide should be enough to help you pick out the right unit.
For greater accuracy, call your water provider.
Tankless Buying Guide: Water Temperature
Once you know the incoming water temperature, you can determine the temperature rise.
Most homes will likely be satisfied with 120°F water, and most units will heat up to 160°F.
To calculate the temperature increase, simply subtract your incoming water temperature from the specified output temperature.
For example, if your water temperature is 68°F and you would like 120°F hot water, the temperature increase would be 52°F.
Finding out water temperature rise enables you to focus on a unit that meet your home's needs.
Your objective is to find a product that provides the needed flow rate at the necessary temperature rise.
Tankless Buying Guide: Best Power Source
Once you understand the temperature rise and flow rate you’ll need from your new water heater, you'll be able to to decide whether an electric powered or gas-powered model will work best for you.
Except small point-of-use heaters, it's most likely that you will need to upgrade your electrical system or the gas supply line and water heater venting.
The primary issues with electric units are with the load they place on your home's electrical system.
They are great for point of use but not for whole-house applications.
Gas and liquid propane are far stronger than electric and will be the type most frequently used as whole-house hot-water heaters.
But there are some things that are critical before making a decision to choose gas:
- Is the gas line size adequate for the unit?
- How will you get rid of the exhaust gases?
- Distance from the meter to the new tankless unit?
- How much gas is used in the rest of the home?
It is recommended that you contact your gas provider or plumber to discuss your options.
Tankless Buying Guide: Gas Piping
Homes with small gas supplies might need bigger diameter pipes to transport more fuel, or the gas provider would need to increase the supply pressure to your home.
Gas repiping involves a large amount of labor, and upgrading the gas service demands a new meter and regulator.
Make sure that the gas-powered models you are looking for use electronic ignition devices, which prevent the frequent fuel consumption of a standing pilot light.
Most tankless heaters employ this technology.
Tankless Buying Guide: Outdoor Installation
If you live in a mild temperate climate, an outside installation is a great choice.
This opens up valuable area indoors, and saves cash by eliminating the cost of ventilation.
Outdoor units are designed with freeze-protection devices which are good down to single-digit temperatures.
Many outdoor units can be installed in a recessed wall box, keeping your house's exterior neat and free of distractions.
Tankless Buying Guide: Condensing Units
- When a hot faucet is opened, the water heater senses flow
- Flow sensor is activated to determine hot water needed
- Igniter is activated
- Gas valve opens up to supply the exact amount of gas
- Fan and venturi are activated to provide fuel
- Premix burner is ignited and provides a flame
- Cold water is heated by the secondary heat exchanger
- Pre heated water flows into the primary heat exchanger
- Unit senses outgoing temperature and adjusts the flame
- Heated water moves to the buffer tank
- Desired hot water amount is delivered to the faucet
Please read our post on Hot Water Recirculation