May 25, 2018
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Tankless water heaters have come a long way

By Tom Gocze, BDN Staff

Back in the late 1980s, I met a guy who was importing tankless water heaters from Europe. He was the first to introduce this product into the U.S. market. I became involved in remanufacturing all the LP gas units that were returned for warranty.

This was an interesting job since I got to see all the mistakes that the factory perpetrated as well as the installer errors. There were some installer errors that were real whoppers.

Although these early units were complicated with a lot of moving parts, they were well-engineered and were fairly reliable. They used a standing pilot light and had no electronic parts.

For a number of years I was nervous about electronics in heating appliances, but the latest generation of tankless gas water heaters are full of electronics and are proving to be quite reliable.

The use of electronics has eliminated a number of moving parts and the unit reliability has actually improved.

I think we rebuilt more than a hundred units. It was a simple process. Having access to the factory service information allowed us to know what was likely to be a problem, and we had all the spare parts on hand.

The installer errors were usually caused by not reading the instructions, although it was obvious that some folks just should not have touched anything mechanical.

We received about a dozen units that were a black mass of burned copper. These made one wonder whether anyone got out alive. Most of the burned units were from someone installing an LP gas unit up to natural gas. This does not work. It is akin to filling a diesel car with gasoline. Not good.

There was one unit that came back with the water connections hooked to the gas line and the gas regulator tied to a water line. I always wondered about that installer.

Most units could be rebuilt, although some made nice scrap metal.

Many people ask about making the change to a tankless gas water heater. It seems that the motivation is to save money. Tankless water heaters operate at the same combustion efficiency as gas tank water heaters do. They save energy because there is very minimal standby loss. These units usually hold less than a pint of water, and the heat loss from that is not significant.

Gas tank heaters can lose a lot of energy during standby mode when there is 30-50 gallons of water sitting. This is significant when you consider that there is a hole in the middle of the tank that allows air that is warmed from the tank to vent out through the chimney, taking valuable stored energy with it. The tankless unit eliminates this issue. They also eliminate the standing pilot by using an electronic igniter.

The other big plus with tankless water heaters is the fact that you can get unlimited hot water. You do not run of out of hot water while taking a long shower. This can be an issue if you have someone who likes long showers. This can negate the energy savings of a tankless through hedonism. The traditional 40-gallon water heater usually will run out in 20 or so minutes — sort of an ad hoc energy savings device.

A tankless gas water heater is not for everyone. It is more expensive than other water heaters. It usually will not corrode like a traditional tank heater will. Although it might require descaling in areas with hard water. This requires a service person coming in and dosing the heat exchanger in the unit with acid to remove mineral buildup. I would not expect to have this problem very often unless you have very hard water. And then a water softener will help minimize this issue.

Most new units come with built-in diagnostics, which can keep service costs down, if and when service is required.

There is a whole new generation of condensing tankless gas water heaters coming out soon that are offering even higher efficiency than the current units.

But be prepared to pay for that extra energy savings in cost and possibly more maintenance.

Questions for Tom Gocze should be mailed to The Home Page, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. A library of reference material and a home-project blog are at

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