A tankless water heater is a wall-mounted unit that heats water only when you open a hot tap, using a gas burner or electric elements. There is no stored volume, so the supply does not run out, but the flow rate is limited by what the unit can heat at once.
We offer same-day appointments when available for service and plan installs on a normal schedule. If your old tank has already failed, water heater replacement is the faster route.
Flushing a tankless water heater in soft Hanahan water
Charleston Water System reports moderately soft water, about 3.4 grains per gallon, and monthly pH between 8.6 and 8.8, with chloramine as the disinfectant. Soft water builds less scale than hard water, so a Hanahan tankless unit usually needs descaling less urgently than one in a hard-water town. That is true, but it is not permission to skip it.
Navien, one major maker, recommends descaling at least once a year and says it may be needed more often with higher mineral content, a higher temperature setting or heavy use. We treat annual flushing as the baseline, and we read your own unit's manual because the interval differs by brand. Flushing also clears sediment that is not hardness, such as rust flakes from older house lines or debris after a main break.
The pH and chloramine are not reasons to worry. They matter here only in that they are the same water running through the heat exchanger every day, and a yearly flush keeps the passages open.
A tankless unit raises the stakes on three code areas: the gas supply, the vent and the electrical supply. The City of Hanahan lists the 2021 International Plumbing Code (IPC), the 2021 fuel gas code and the 2020 National Electrical Code (NEC), each with South Carolina modifications.
The manufacturer's manual adds its own requirements for venting and clearances. The installer follows both, and the City's Building and Codes department can tell you how permitting applies.
Sources: City of Hanahan, Building Codes and SC LLR, Building Codes in Effect for South Carolina. Checked October 2026.
How a tankless flush works
The flush is a closed-loop circulation of a descaling solution, not a rinse.
- 1
Shut off gas and power
Close the gas valve and unplug or switch off the unit.
- 2
Close the water valves
Cold inlet and hot outlet isolation valves closed, using the service ports built into most units.
- 3
Connect the pump and solution
A small pump and bucket circulate a descaling solution, often food-grade vinegar or a manufacturer-approved cleaner, through the heat exchanger. Use what your manual permits.
- 4
Circulate and rinse
Run for the time your manual specifies, then flush with clean water until it runs clear. Clean the inlet screen.
- 5
Restore and test
Reopen the valves, purge air, restore power and gas, and check for error codes and leaks.
Signs your tankless heater needs attention
Symptoms usually show up before an error code does.
- Hot water that fluctuates from hot to lukewarm during a shower (the cold-water sandwich).
- Longer wait for hot water at a tap than before.
- Error codes for ignition, flame, overheating or low flow.
- Rumbling, popping or kettle-like noises while heating.
- A drop in hot flow at the faucet that cold flow does not share.
- Clogged inlet screen or visible debris when the screen is cleaned.
A flow problem can be a plumbing issue elsewhere, such as a stuck mixing cartridge. We check that before we pull a unit apart.
Ready to book?Call and we will find the earliest slot, often the same day when the schedule allows.
Call (855) 575-2890Is a tankless water heater right for your Hanahan home?
The U.S. Department of Energy says demand-type heaters can be 24 to 34 percent more energy efficient than storage heaters for homes that use 41 gallons or less of hot water a day, and 8 to 14 percent more at about 86 gallons a day. DOE also says most tankless units last more than 20 years, against roughly 10 to 15 years for storage tanks. The savings depend on how much hot water you use.
The trade-off is that the unit must heat a lot of water fast. A gas tankless often needs a larger gas line than a tank, a stainless or PVC vent through a wall, and a condensate drain. An electric tankless can need a very large circuit. Many Hanahan houses were built in the 1970s growth, so panel and gas line capacity are the first things we check, not the last.
If you shower and run the dishwasher and laundry at once, size by peak flow, not by household headcount.
Tankless or tank: how they compare in practice
A side-by-side look at what changes in your house.
| Topic | Tankless | Tank |
|---|---|---|
| Hot water supply | Continuous, limited by flow rate | Limited by tank size, then recovery |
| Space | Wall mount, small footprint | Floor space, tall |
| Energy use | No standby loss, per DOE | Standby loss while the tank holds heat |
| Expected life | More than 20 years per DOE | About 10 to 15 years per DOE |
| Upfront work | Gas line, vent and electrical often change | Often a like-for-like swap |
| Maintenance | Annual flush, screen clean | Occasional drain, anode check |
| Failure mode | Error codes, heat exchanger scale or damage | Tank leak |
DOE figures come from its tankless guide on energy.gov. Your results depend on your usage and fuel prices.
Tankless water heater installation and conversion
Converting from a tank to a tankless unit is a small remodel. The old vent is usually the wrong size, the gas meter may need to support a higher load, and the new unit needs a condensate path and a relief valve. Power-vent models also need an electrical outlet nearby. We design the job around the vent route and gas capacity first, and the unit second.
On a first call we ask about the gas meter, the current line size, the location and the vent path, then we explain which parts have to change. We refer gas utility questions to Dominion Energy and permit questions to the City of Hanahan Building and Codes department. Our water heater installation page lists the parts any install needs.
Common tankless problems we diagnose
Most service calls fall into one of these groups.
Ignition and flame errors
Dirty flame sensor, blocked vent, low gas pressure or an undersized gas line.
Overheat and temperature faults
Restricted flow from scale, a clogged inlet screen or a failed sensor.
Cold-water sandwich
Not a defect. Recirculation loops and small buffer tanks reduce it.
Low flow
A partially closed isolation valve, a clogged filter, or a fixture issue.
Leaks at the unit
Loose fittings, failed isolation valve seals or a cracked heat exchanger.
What affects the price of tankless service
Installation and service are priced differently, and these factors drive both.
- Gas line and electrical capacity
- A larger gas line or a new circuit can be most of the cost of a conversion.
- Venting
- Wall penetrations, vent materials and condensate drain add labor.
- Unit type and size
- Condensing, non-condensing, indoor, and different flow ratings.
- Water quality and condition
- A neglected unit may need a longer descale. Soft CWS water usually helps.
- Isolation valves
- Units without service valves cost more to flush until they are added.
Maintenance and upgrades are generally not covered by homeowner insurance. If a tankless unit fails suddenly and damages a floor, damage coverage may apply. Ask your carrier.
Call with your unit's model, and we will give a clear price before work starts.
Working with the rest of your plumbing
If your tankless is paired with older lines, a leak detection check can find a slow problem before it matters. For a failed old tank, water heater repair helps you decide. We serve Hanahan and nearby towns, including North Charleston.
Frequently asked questions
How often should I flush a tankless water heater?
Navien recommends at least once a year, with more often in higher-mineral water or heavy use. Check your own manual, since brands differ.
Does Hanahan's soft water mean I can skip flushing?
Not safely. Scale builds slower in soft water, but sediment, rust flakes and debris still collect, and manufacturer guidance still calls for periodic flushing.
Can I flush a tankless heater with vinegar?
Many manuals allow it, but follow yours. Use the right pump, the right time and a full rinse.
How much do tankless heaters save?
DOE says 24 to 34 percent for homes using 41 gallons or less a day and 8 to 14 percent at about 86 gallons a day. Your use sets your result.
Why do I get hot then cold then hot water?
That is the cold-water sandwich. Cold water in the pipes arrives between bursts of hot. A recirculation loop or buffer tank helps.
Does my unit need isolation valves?
They make flushing possible. Without them, we add a service valve kit.