Tankless Gas Water Heaters – Important Considerations

What Is A Tankless Gas Water Heater?

A tankless gas water heater is a type of water heater that heats the water you use instantaneously, whereas a conventional water heater continually heats a “held” tank of water to a constant temperature, all the time. In many cases, a tankless water heater can provide significant savings over a conventional one, depending on how you use water, and where your water heater is in your home.

Five Important Things To Know About Tankless Water Heaters

Should you use natural gas or propane?

A gas tankless water heater is going to use natural gas or propane. The water heater itself is specific to the fuel type, although the venting and installation will be the same regardless of the type of fuel you use. If you do wish to convert from one type to the other, most manufacturers will offer conversion kits; consult a professional in home heating if you don’t know exactly what to do.

Piping and retrofitting

Tankless gas water heaters are “on demand” water heaters; this means they require more fuel to heat water then conventional tanks do, which simply store hot water all the time. This often means that houses need to be retrofitted with larger gas pipe fittings to accommodate a tankless gas water heater, from 1/2″ pipe to 3/4″ pipe.

Application and venting

Tankless gas water heaters need air both for combustion and for venting. The right amount of air intake is essential for proper function and efficiency. There are lots of venting options to choose from, with some venting vertically and some venting horizontally. All exhaust air will travel outdoors, though. The venting options you have with your particular home may also determine to some extent where the tankless gas water heater is going to be installed.

The option you choose can limit the location of installation, so make sure you have everything worked out in regard to ventilation before you purchase your tankless gas water heater.

Fan assisted ventilation

A fan can assist with ventilation to the outdoors, and can also provide the unit the air it needs to operate.

- Sealed combustion or direct ventilation

You can also utilize what’s called “sealed combustion” or “direct ventilation”. In this case, the air needed for combustion and operation comes from the outdoors, not inside. Two “air” pipes are installed, one for air intake and the other for the exhaust. You can also do this with an indoor application, either horizontally or vertically ventilated.

- Completely outdoor ventilation

An outdoor vented tankless gas water heater is recommended only for outdoor installation, and is generally only used in warmer climates.

Pilot light, or intermittent ignition device?

Some tankless gas water heaters have a pilot light, while others have something called an intermittent ignition device. Newer gas ovens use these devices, too, instead of relying on a pilot light. In general, the newer IID devices are recommended, since tankless gas water heaters with pilot lights must burn continuously and will offset some energy savings normally seen with the tankless water heaters.

Flow rates

Finally, you’ll need to determine what the flow rates of devices consuming hot water will be. This will determine the best model of tankless gas water heater for your purposes.