Rinnai Tankless Water Heater Replacement in Goodyear, AZ — A Two-Year-Old RE160e Leaking From the Bottom, Replaced With an RE180

By Donnie Jablonowski, Owner — Pridemark Plumbing · Licensed Arizona Contractor, ROC #319398

You walk around the side of the house and there’s water on the ground under your tankless water heater. Not a little condensation on a warm morning. It’s coming out of the bottom of the cabinet, and when you crouch down you can see it running through the fan housing. If that’s what you’re looking at, you’re past the wait-and-see stage, and your gut is right: water shouldn’t be moving through a box that also holds a gas burner and a circuit board.

In September 2026, a homeowner in the Avion at Ballpark Village community of Goodyear, AZ called us with exactly that. Their outdoor Rinnai RE160e was about two years old, installed when the house was built, and leaking from the bottom hard enough that water was running through the fan. Here’s what Donnie found when he pulled the cover, how the warranty case played out, and why the new heater on that wall is one size bigger.

Why Was a Two-Year-Old Rinnai Leaking From the Bottom?

Because the heat exchanger had failed. A tankless water heater doesn’t store hot water. It heats water on the way through, inside a heat exchanger, the copper coil at the top of the cabinet. In Rinnai’s RE Series the burner and gas manifold sit below the exchanger, and the combustion fan, the fan that feeds air to the burner, sits below those. So when the exchanger cracks or corrodes through, the water drips down through the burner and the fan on its way out the bottom, which is exactly what this homeowner was seeing.

What Donnie found with the cover off

Donnie shut off the water and the gas, pulled the front cover, and the story was right there. One corner of the gas manifold, the pipe that spreads gas to the burners, was corroded. The burner orifices, the small brass jets that feed gas to each flame, had heavy corrosion around them. Even the gas shutoff had a light coat of rust starting. That’s months of a small leak nobody could see from outside, and it’s why a “little drip” under a tankless deserves more attention than it usually gets. The same parts fail in different ways: on a Rinnai in Buckeye, the heat exchanger and fan unit were the repair. Here the exchanger was done, the unit was two years old, and its coverage was still active, so the path was different.

What Happens If You Keep Running a Leaking Tankless Water Heater

The leak doesn’t heal on its own. The unit keeps firing every time you open a hot tap, and each cycle pushes more water through the crack. Water on a spinning fan motor and its wiring is asking for a short, and the corrosion keeps creeping toward the gas valve and the control board, the two parts you least want wet. The usual ending is a heater that throws an error code and quits on the one morning you can least afford it. The ending you really want to avoid is a corroded gas connection on the side of your house.

How the Rinnai Warranty Case Worked

A two-year-old heater gets treated differently from a fifteen-year-old one. Rinnai’s published terms give a new tankless one year of labor coverage, and registering the unit extends that to five. This RE160e was registered and still covered, so Donnie got Rinnai tech support on a video call, walked the camera over the failed exchanger and the corrosion, and opened a warranty case with the failure on record. Rinnai reviewed what the unit showed, authorized a replacement under that case, and told us the coverage carries over to the new heater.

That video call is worth knowing about if you ever have a young tankless fail. The manufacturer wants to see the failure, not hear about it secondhand, and a plumber who documents it on the spot keeps the paperwork from dragging on for weeks. We walked the same path on a Rinnai tankless warranty replacement in Glendale. Not sure yours was ever registered? It’s worth ten minutes to find out, because registration is the difference between a covered replacement and a new-heater invoice.

Why the Replacement Was a Bigger Unit: RE160e vs. RE180 for a 2.5-Bath Home

The RE160e is a good heater, and in plenty of homes it’s the right one. What stretches it is overlap. This home has about 2.5 bathrooms plus a washer and dryer, and the demand that matters is the peak: two showers running while the washer fills with hot water. A tankless holds your set temperature first, so when more taps open than it can heat to that temperature, it limits the flow instead of sending cooler water. Somebody in the house notices.

The numbers explain the upgrade. Rinnai rates the RE160 at up to 6.6 gallons per minute and the RE180 at up to 8.5, and how much of that you actually get depends on how far the heater has to raise the incoming water. With the warm water Arizona sends into a heater most of the year, Rinnai’s own flow chart puts the RE180 near 6 gallons a minute and the RE160 near 5.3. That’s close to a gallon a minute of extra room, roughly one more fixture at the same time, without running a brand-new heat exchanger at its limit every busy morning. Our tankless water heater page covers how we size one to a home instead of to a bathroom count.

How We Replaced the Tankless Water Heater in Avion at Ballpark Village, Step by Step

Here’s the work Donnie did at this home, in order:

1. Shut off the water and gas and removed the RE160e. Closed the water and gas shutoffs, disconnected the failed unit, and took it off the wall.
2. Mounted the new Rinnai RE180 outdoor natural gas tankless. Rinnai’s full model code is RE180eN, “e” for exterior and “N” for natural gas. Same outdoor wall, more capacity.
3. Installed a brand-new flexible gas connector. The connector, the short flexible “whip” between the house gas pipe and the heater, is a one-installation part, and its makers print “do not reuse” in the instructions. The gas side of a heater swap gets the same care as any gas line repair.
4. Made up the water connections. Reconnected the hot and cold lines to the new heater and checked them dry.
5. Verified the burner’s high and low gas pressures. With a manometer, a gas-pressure gauge, on the burner’s test port, Donnie confirmed the pressure at the lowest flame and the highest against Rinnai’s settings, adjusting where needed.
6. Ran the hot water and confirmed the heater did its job. Opened fixtures inside the house and watched the unit fire, come up to temperature, and hold it.

What this home gets: more hot water when everything runs at once, a new gas connection instead of a corroded one, a dry cabinet, and a warranty case behind the new heater. Morning routines stop being a negotiation between the hall bath and the laundry room.

Hard Water, Scale, and the Softener Estimate We Left Behind

This home is on city water with no softener, like a lot of newer West Valley homes. The U.S. Geological Survey calls water “very hard” once it passes 180 milligrams per liter of calcium carbonate. Rinnai’s installation manual sets its hardness guideline at 200 milligrams per liter, about 11.7 grains per gallon, and the City of Goodyear’s own water quality guidance tells residents to set a softener for 14 to 20 grains per gallon. In other words, the water here starts out harder than the heater’s guideline.

When hard water is heated, minerals come out of it and crust the inside of the heat exchanger. That coating is scale. It insulates the copper so the burner has to run hotter to push the same heat through, and Rinnai points to those hot spots when it troubleshoots a failed exchanger. Rinnai’s warranty also excludes damage caused by poor water quality and scale, and its manual says that where the water is known to be hard, it must be treated.

So we sent the homeowner an estimate for two things: a water softener, which removes the minerals before they reach the heater, and a Scale Guard, a scale inhibitor that keeps the minerals that remain from bonding to the exchanger. That estimate is the homeowner’s decision, and nothing on it has been installed. See our water treatment and purification page for the options, and the whole-house softener we installed in Estrella Mountain Ranch for what that job looks like across town. Softener or not, a tankless on hard water should be flushed on a schedule, and that flush is part of the maintenance visit under our Service Agreement.

Before We Left

Donnie verified the gas pressures, ran the hot water, and left the homeowner with two things: a heater sized for the way the family actually uses hot water, and the water treatment estimate to think over on their own schedule. For our neighbors in Avion at Ballpark Village and across our plumbing services in Goodyear, AZ area, that’s how a warranty replacement should go: the new heater fits the house, and the next decision belongs to the homeowner.

Why an Outdoor Gas Tankless Swap Is a Licensed-Plumber Job

An outdoor gas tankless swap touches natural gas, water, combustion air, and the manufacturer’s warranty all at once. The gas connector has to be new and tightened right. The burner’s gas pressure has to be verified at low fire and high fire. The warranty case has to be documented the way the manufacturer expects, and Rinnai itself recommends a trained professional for the install and says improper installation may void the warranty. Tank or tankless, our water heater installation work follows the same order: size it to the home, connect it right, set it to the manufacturer’s numbers, and run it before we leave.

Questions West Valley Homeowners Ask About Leaking Tankless Water Heaters

Why is my tankless water heater leaking from the bottom?

Most often the heat exchanger, the copper coil where the burner heats your water, has cracked or corroded through, and water is escaping inside the cabinet. Water running through the fan housing, as on this Rinnai RE160e, means the exchanger has failed rather than a fitting weeping. Shut off the water to the unit if you can reach the valve safely, then call a plumber.

Can a Rinnai tankless water heater be replaced under warranty?

It can, when the unit is registered and the case is documented the way Rinnai asks. On this job we recorded the failed heat exchanger on a video call with Rinnai tech support, opened the case, and Rinnai authorized a replacement unit. Labor coverage was still active because the unit had been registered, and Rinnai told us the coverage carries over to the new heater.

How do I know if my tankless water heater is too small for my house?

Watch what happens when two things run at once. A tankless holds its set temperature by limiting flow, so when demand passes what it can heat, a second shower or a washer fill turns the first shower into a trickle. Sizing is about peak overlap, not bathroom count alone. On this 2.5-bath home, the RE180 adds close to a gallon a minute over the RE160e at Arizona water temperatures.

Do I need a water softener with a tankless water heater in Goodyear, AZ?

It isn’t required, but it’s what protects the heat exchanger from scale. The City of Goodyear tells residents to set a softener for 14 to 20 grains per gallon, above Rinnai’s own hardness guideline for its heaters, and Rinnai’s warranty excludes damage from poor water quality. A softener, a scale inhibitor like Scale Guard, or both is the usual pairing. For this home, the estimate is with the homeowner to consider.

Can the old gas connector be reused when a tankless water heater is replaced?

No. The flexible gas connector, the “whip” between the gas pipe and the heater, is a one-installation part. Its makers print “do not reuse” in the instructions, and the U.S. Consumer Product Safety Commission says connectors should always be replaced whenever the appliance is replaced or moved. We install a new connector on every replacement.