On-Demand Units Serviced
Tankless Water Heater Service in Roswell, GA
Descaling, error-code troubleshooting, repairs and tank-to-tankless conversions for Roswell homes. We start with the code on the display and the model on the label.
- Error-code diagnosis
- Descaling and filter service
- Conversion estimates free
Tankless Quick Facts
Keep the model number handy when you call.
Sound Familiar?
Hot Water Goes Cold Mid-Shower, or the Display Shows a Code
Those two complaints account for most tankless service calls, and people rarely search for "tankless service" when they happen. They search for the symptom. The shower runs hot, then cold, then hot again. Or the unit shuts off and flashes a two or three digit code nobody in the house understands.
Both usually trace back to a short list: a clogged inlet filter, scale on the heat exchanger, a gas line too small for the unit, a venting problem, or a flow rate too low to keep the burner lit. Tankless water heater service is the work of finding which one and fixing it, plus the routine descaling that keeps these units running.
Roswell 24/7 Plumbing services tankless water heaters across Roswell, in 30075 and 30076, and in nearby Milton, where larger homes often run tankless units sized for several bathrooms.
Troubleshooting
Tankless Problems and Their Usual Causes
A starting point before the visit. The error code narrows it further.
| Problem | Common causes | Typical fix |
|---|---|---|
| Hot, then cold, then hot | Low flow, dirty filter, scale | Clean filter, descale, check mixing valve |
| Unit will not ignite | Gas supply, igniter, flame sensor | Check gas pressure, clean or replace sensor |
| Shuts off under heavy use | Undersized gas line or unit | Gas line upgrade or add capacity |
| Error code after rain or wind | Venting or intake blocked | Clear and reseal vent termination |
| Lukewarm water only | Scale on the heat exchanger | Descale with a pump and cleaning solution |
Error Code on the Display?
Read it to the dispatcher along with the model number. It often points straight to the cause.
Descaling in Soft-Water Roswell
Scale forms when minerals in heated water drop out onto hot metal. In hard-water regions, tankless heat exchangers can clog in a year or two without service. Roswell's water sits at roughly 1.5 grains per gallon in public hardness data, which counts as soft, so scale builds slowly here.
That is good news, not a license to skip maintenance. Most manufacturers still call for periodic descaling, often yearly, and many warranties depend on it. A descale runs a food-safe cleaning solution through the heat exchanger with a small pump for about an hour, using isolation valves on the inlet and outlet. Units installed without those valves are harder to service, and adding them is worth doing on the first visit.
The inlet filter screen needs attention too. Grit from a nearby water main repair can clog it faster than minerals ever will.
Before a Tank-to-Tankless Conversion
Most surprises in a conversion come from these five items. Check them before you commit.
- Gas capacity. Large gas tankless units need far more fuel at full fire than a tank. The existing gas line and meter have to be able to supply it.
- Venting route. Condensing models vent through PVC, often out a side wall. The route has to meet clearance rules from windows and doors.
- Condensate drain. Condensing units produce acidic condensate that needs a drain, sometimes with a neutralizer.
- Power. Even gas tankless units need a nearby outlet for controls and fans.
- Permit. In Roswell, replacing a water heater requires a City permit and inspection, and a conversion is no exception.
If any of these look complicated, a standard tank or heat pump model may be the better value. The water heater repair page covers keeping an existing tank running instead.
Cost
What Drives the Cost of Tankless Service
Routine service is predictable. Repairs and conversions depend on what the unit and the house need.
Conversions are planned work and get a free estimate. Rebates for efficient water heaters change often, so ask your gas provider what is currently offered.
Want your tankless unit looked at? Call (770) 214-4545.
Questions
Tankless Questions From Roswell
Write down the code and the model number from the label, then check whether the unit has power and gas. Many codes point to ignition, flame loss, venting or overheating, and some clear after a reset. If the code comes back, call with it. The plumber can often narrow the cause before arriving.
The most common causes are a flow rate below what the unit needs to stay lit, a dirty inlet filter, scale on the heat exchanger or a gas supply that cannot keep up. A mixing valve set too cold can cause it too. Cleaning the filter and a descale often solve it.
Manufacturers commonly suggest a descale about once a year, and some ask for more frequent service in hard water. Roswell's water is soft, so many homes can follow the manual's standard interval without problems. Follow your unit's manual, since skipping required maintenance can affect the warranty.
Usually, but check three things first. Gas tankless units need a larger gas supply than most tanks, often more than the existing line provides. They need their own venting, commonly PVC for condensing models. And they need an electrical outlet for controls. A site visit answers all three.
They never run out the way a tank does, but they have a flow limit. Run too many fixtures at once and the temperature drops. Sizing the unit for your busiest hour prevents it.
That comes down to how much hot water you use and how many years you expect to live in the house. The energy savings add up slowly in low-use households, and conversion costs are real. For a straight comparison, see the options on our water heater replacement page.
Sources for This Page
Water hardness reflects public hardness data for ZIP 30075. Permit requirements come from the City of Roswell Community Development FAQ. Descaling intervals and conversion requirements reflect common manufacturer installation and service manuals.
Written by the Roswell 24/7 Plumbing team and checked against the sources above. Last reviewed October 1, 2026.
Tankless Unit Acting Up?
Call with the error code and model number, and get a straight answer on repair or service.
Call (770) 214-4545