First decide whether you need to replace it at all
Tankless units fail in two broad ways. Many problems are maintenance, such as scale in the heat exchanger or a clogged inlet screen, and a flush clears them. Others are real failures, such as a cracked heat exchanger or a dead control board.
Before you buy a new unit, note the error code on the display, the brand and the age. That information separates a service visit from a replacement and keeps you from paying for equipment you do not need.
Signs a tankless heater is near the end
A tankless heater is built to last longer than a tank, but it does not last forever. These signs point toward replacement rather than another repair.
Repeated error codes after a flush
If a descaling flush does not clear the fault, the heat exchanger or a sensor may be failing.
Water that never gets fully hot
A unit that cannot reach set temperature even at low flow often has a worn burner or heavily scaled exchanger.
Leaks inside the cabinet
Water at the base of the unit may come from a loose fitting, but a leaking heat exchanger cannot be patched.
Cost of repairs adds up
When the second or third repair is on the table, compare it with the cost drivers of a new unit.
Repair, flush or replace
| Symptom | Likely cause | Usual response |
|---|---|---|
| Lukewarm water, code for flow or temperature. | Scale or a clogged inlet screen. | Descaling flush and clean the screen. |
| Unit will not ignite. | Gas supply, igniter or flame sensor. | Service visit, repair if parts are available. |
| Intermittent cold sandwich in showers. | Low flow, a sensor fault or recirculation setup. | Diagnose before replacing anything. |
| Water leaking from the heat exchanger. | Corrosion or freeze damage. | Replace the unit. |
| Many repeat faults on an old unit. | General wear on boards and valves. | Replace and review the venting. |
Maple Heights water and what it does to a tankless unit
Cleveland Water, which serves Maple Heights, reports an average total hardness of 117 in its 2025 water quality report. That is about 6.8 grains per gallon, which counts as moderately hard water.
Hard water leaves scale on the heat exchanger, and a tankless heater is more sensitive to scale than a tank because its water passages are narrow. Ask a plumber about a yearly flush schedule. If you want to know your own tap, test it or ask the water utility.
Source type: Utility reportWhat the swap involves, step by step
This is the order a plumber follows. It also shows why the job is more than a plug-in change.
Shut off fuel, power and water
The gas valve, the electrical supply and the water isolation valves are all closed before anything is touched.
Drain and disconnect the old unit
The unit still holds water and may have scale and hot components. Disconnect gas, water and vent in that order.
Check the lines and vent path
Gas pipe size, vent material, the condensate drain and isolation valves must match the new unit's specification.
Mount, connect and test
The new unit is mounted, connected and run through a leak, ignition and temperature test before the job is finished.
Not sure it is time to replace?
Call and tell us the error code. We will say whether it needs a flush, a repair or a new unit, and give you the price first.
What a homeowner can do and what needs a plumber
Reasonable for a homeowner
- Note the error code and model number
- Clean an accessible inlet screen with the water off
- Run a flush if the maker provides isolation valves and instructions
- Clear the area around the unit
Needs a licensed plumber
- Disconnecting or reconnecting a gas line
- Changing the vent type or routing
- Sizing a new gas pipe or electrical circuit
- Replacing a leaking heat exchanger or control board
- Anything requiring a permit or inspection
Why older Maple Heights houses need extra checks
About 68 percent of Maple Heights homes were built before 1960, based on older survey data. Many were built with tank heaters and a gas line sized for a tank, not a tankless unit that draws much more gas at once.
A plumber will check whether the existing gas line can feed a tankless heater and whether the old chimney or vent works with the new unit. If you are going from a tank to tankless, our tankless water heater page explains the planned installation. If the old unit is a tank that has failed, water heater replacement covers that path.
After the swap, keep a simple log
Write the install date, the model number and the first flush date on a piece of tape near the unit, or in your phone. When a technician comes later, that note saves a lot of guessing about age and service history.
Set a reminder for the first flush using the maker's schedule, and ask the installer to show you where the service valves sit. Knowing which handle isolates the unit turns a future leak from an emergency into a small job.
Permits and inspections
Gas and venting work can require a permit and inspection. The Maple Heights Building Department handles permits, and work that needs one must be approved before it starts. We could not confirm the specific water heater rule, so ask the city Building Department and confirm who pulls the permit before the swap is booked.
Serving nearby homes
We replace and service tankless heaters for homeowners across Maple Heights, and in nearby Warrensville Heights and Walton Hills. Tell us your address and the unit's brand when you call.
Frequently asked questions
Makers commonly rate them for many years of service, but life depends on water quality and maintenance. Regular flushing in hard water helps.
Yes, if the space, gas and venting suit a tank. We can compare the options for your house.
Cleveland Water reports moderately hard water, so scale can build up over time. Ask about a regular flush schedule.
Many are, but venting, gas line or electrical changes can add time. We confirm the scope before the work starts.
Call the 24/7 line. We can troubleshoot by phone and send a plumber if the cause is more than a quick fix.
Yes. You get a clear price before work begins and we explain what might change it.