Common tankless water heater problems
- Error codes on the display, which point to ignition failure, flame loss, overheating, venting or flow sensor problems
- Cold-water sandwich: bursts of cold water between hot, often from the unit cycling at low flow
- Water never gets hot at low flow, such as a single faucet
- Fluctuating temperature when more than one fixture is running
- The unit shuts down mid-shower, often from scale, a dirty inlet filter or a venting issue
Scale is the number one enemy
Tankless units heat water quickly through a small heat exchanger, and minerals in the water stick to it. Over time the scale insulates the exchanger, makes the unit overheat and triggers errors. Most manufacturers recommend descaling, or flushing the unit with a cleaning solution, about once a year, and more often with hard water. Well water in many rural Connecticut towns can carry minerals and sediment, so homes in places like Southbury, Guilford or Granby may benefit from a scale-reducing filter ahead of the unit.
How tankless repair works
- Call and have the brand and any error code ready. We connect you with a local pro.
- Diagnosis. The tech reads the code history, checks gas pressure or electrical supply, inspects the inlet filter, flame rod and venting, and checks the flow sensor.
- Repair or descale. Many fixes, such as cleaning, descaling, sensor or igniter replacement, can be done on site. Some parts may need to be ordered.
- Prevention. Ask about installing isolation valves if your unit doesn't have them. They make yearly descaling quick.
Tankless installation and conversions
Thinking about going tankless? It's a good fit for many Connecticut homes with natural gas or propane. The install usually involves a larger gas line, new venting through the wall and sometimes a condensate drain. Electric tankless units for a whole house need a lot of amperage, so a panel check is essential. If you're replacing a tank, ask for quotes on both; our water heater replacement page compares the options.
Tankless units are popular in homes around Westport, Fairfield, Glastonbury and Madison, where saving space and having endless hot water both appeal. For other types of units, see gas water heater repair or our main page on water heater repair services in Connecticut.
Frequently asked questions
How often should a tankless water heater be descaled?
Most manufacturers recommend about once a year, and more often with hard or mineral-heavy water. Check your owner's manual for the specific schedule.
Why does my tankless water heater go cold in the middle of a shower?
Common causes include scale buildup on the heat exchanger, a clogged inlet filter, low gas pressure or a venting problem. The unit's error code will help the technician narrow it down.
What does a tankless water heater error code mean?
Each brand uses its own codes, but they typically point to ignition, flame, overheating, venting or water flow problems. Note the code before you call. It speeds up the diagnosis.
Can I switch from a tank to a tankless water heater?
In most homes, yes. It usually needs a bigger gas line, new venting and sometimes a condensate drain, or significant electrical capacity for electric models. A pro can tell you what your home needs.