subject: Gas Tankless Water Heaters - Critical Considerations [print this page] Gas Tankless Water Heaters - Critical Considerations
Gas powered tankless water heaters are becoming more and more widespread in North America thanks to their efficiency, low maintenance, reliability and of course, the promise of an unending supply of hot water. If you are considering installing a gas tankless water heater in your new home or replacing an existing standard storage tank heater, here are a few important things to keep in mind before making your final decision.
Placement & Pipe Runs
Gas tankless water heaters have seen significant technological improvements in recent years but they still take a couple of seconds to bring a flow of water to your specified temperature. So to reduce the time you spend waiting on the hot water to arrive, it's important that the heater be located as close as possible to the kitchen, bathroom or other outlet where the hot water is needed. This can be tricky with a gas heater due to venting issues (discussed below). Consult with a licensed plumber to determine the maximum distance that will give you satisfactory performance. If the distance is too great, installing smaller, electric point-of-use heaters at strategic locations in your home may be an alternative.
Gas Requirements
Gas tankless water heaters are much more efficient than a conventional storage tank system over time but they do require a great deal of fuel when firing. Thus, many gas fired models, like the Bosch 2700ES NG, require a 3/4 inch gas line to ensure an adequate flow of natural gas or propane. Many older homes are equipped with only a 1/2 inch gas line and must be upgraded before the tankless heater can be installed.
Combustion & Venting
Modern gas tankless water heaters burn hotter and faster than a standard heater and even many furnaces. Thus they require a lot of available air for combustion and special venting to ensure exhaust fumes are handled correctly. For combustion the heater must be installed in a well ventilated area or have an intake duct installed that leads to the exterior of the home. Installation in an attic is typically suitable as there is plenty of air circulating thanks to the venting required in attics. Basements are usually another matter though, and an air intake must be professionally installed.
Venting is also crucial due to the volume of exhaust produced while the unit is running. The required ducting is usually stainless steel and must adhere to strict standards of operation. If your home is not already equipped with this style of venting this can easily double the cost of installing a gas tankless water heater.
