Retrofit, maintenance can curb charm of tankless water heaters

by Judy Stringer

It’s not hard to see the appeal of tankless water heaters.

Because water is heated as it passes through the system, you’re only warming water when you need it. That translates into lower utility bills and a smaller carbon footprint. Tankless units are also more compact than the conventional tank water heaters – i.e. they take up less of your precious storage space – and have a longer lifespan with warranties of up to 25 years compared to tank systems that tend to fizzle out in about eight to 10 years.

If you have a large household or high water demands, there’s another benefit as well: an endless supply of hot water. You won’t run out as you do when a tank water heater empties.

But tankless water heaters aren’t without their drawbacks, starting with installation costs, according to Broadview Heights Plumbing owner Steve Whitney.

“When you have an existing house that has a tank, most of the time it’s going to be cheaper, much cheaper, to replace that with another tank than it is to get a tankless water heater,” he said.

The problem, Whitney explained, is not the cost of the system itself. Tankless water heaters run anywhere from $600 to $1,500 depending on the model. The issue is the retrofit, which drives up labor and material expenses. Gas-fired tankless units must be mounted on an outside wall so they can be piped directly to the outside. They can’t be vented through a chimney. So, if your existing water heater is in the middle of the utility room or the center of your house, you’re going to have to extend both gas and water lines to a new location.

Whitney said tankless water heaters often require larger gas lines, too. While a conventional water heater tank might have a 50,000-BTU gas line, a tankless can require up to four times that. For this reason, it is likely that you will have to run a newer, larger gas line to feed your tankless water heater.

All in, he estimated replacing a standard storage water heater with a tankless one will cost a homeowner north of $5,000 versus around $2,000-$2,500 for a standard storage water heater installation. 

Maintenance can be another drawback, said Approved Plumbing employee Jeff Schlekie.

“Tankless water heaters need to be flushed,” he said. “It used to be every year but some of the newer products say they can be serviced, or flushed, every two years.”

While homeowners can learn to flush the system themselves, people tend to forget or simply don’t get around to it.

“Sometimes it’s easier to have it done by a professional and have it scheduled ahead of time,” Schlekie said.

Mineral deposits will build up in units that aren’t properly flushed, he added, which can block water flow, prevent the unit from heating water and/or void the warranty.

Whitney said not flushing tankless systems might also put electronic sensors at risk, which brings up another disadvantage – “the electronics on those units, when they go bad, they aren’t cheap to replace,” he said.

While each home is different, Schlekie and Whitney agreed that tankless systems tend to make the most sense in new construction when the plumbing network can be built to accommodate their special needs.

“That’s not to say, we don’t have some existing homes where the retrofit was not too difficult or where the homeowners are focused more on the future savings and energy efficiency than the upfront investment,” Schlekie said. ∞