Tankless water heaters are touted as an energy saving way to deliver hot water to households. While novel in the States, tankless water heaters have been used in Europe for decades. They look like a large suitcase secured to the wall. Instead of heating and storing the water, as in conventional water heaters, the tankless water systems use a heat exchanger to instantly heat the water. No storage tanks.
After considerable research, our family installed a natural gas tankless water heater over a year ago. We love it, but the tankless heaters are not for everyone. Here are some things to consider before replacing your hot water system with a tankless version.
Cost. One-for-one, a tankless water heater is much more expensive than a conventional water heater. An October 2008 Consumer Reports article found tankless water heaters would likely return an energy savings to consumers of about $80 a year. It would take the average family over 20 years to recoup the extra expense for an energy efficient tankless system. Don’t write that tankless heater off yet. In our family’s case, we replaced two conventional hot water heaters with a single tankless heater – this two for one replacement coupled with the tax credit under the American Recovery and Reinvestment Act made the installation of our system less expensive than a conventional water heater. For more information on the specifics of the tax credit visit the Energy Star website.
Output constraints. Because it does not store hot water, the tankless heater is restricted to a hot water outflow of between 3 – 6 gallons per minute. If you intend to run three showers, the dishwasher and washing machine simultaneously, you may have a problem. Our family tends to shower sequentially not in parallel. Over the last year, our family has had no problem with running out of hot water. We haven’t tested the limits of our system, but we do occasionally run dishwasher and shower together – once again, without problems.
And while there may be a flow restriction to several gallons a minute, there is no capacity restriction. Your hot water could, theoretically, run all day – you aren’t limited to the hot water capacity of storage tanks. This unlimited capacity is what allowed our family to replace two conventional water heaters with a single tankless system.
Maintenance. We live in North Texas. The dissolved minerals in our hard water can lead to scaling (mineral deposits) within the tankless system potentially degrading its life span and efficiency. To keep your warranty intact and to prolong the life of the system, an annual system flushing is needed. If done professionally, this will cost about $300 annually. You can buy the equipment and conduct the flushing yourself. I should, in fairness note that conventional storage water heaters should be flushed annually too.
Installation. Installation is relatively easy if you have sufficient capacity on your gas line. In our case, the most difficult part of the installation was the removal of the old hot water heaters. A tankless water heater requires a ¾” gas pipe and is a tremendous BTU draw. Make sure you check out in advance if your system can accommodate the tankless system. Tankless systems are also relatively novel in our area. Check out your installer with the Better Business Bureau. Pay a little more if you need to, but make sure whoever installs your system has already installed that model dozens of times before.
Our family is happy with our tankless water heater. We feel a little greener with our energy saving system. However, a lot more than just environmental considerations need to go into this decision.