Tankless & on-demand
Tankless water heater repair in Plymouth
Licensed & insured · Available 24/7
Wall-mounted gas tankless units are efficient, but they're less forgiving about scale, venting and gas supply. Our plumbers diagnose error codes, ignition and flow faults, and assess whether descaling is needed.
- Error code on the display
- Hot, then cold, then hot
- Won't fire at low flow
- Reduced hot-water flow
- Unit shuts off mid-shower
Error codes are a starting point
A code identifies which sensor tripped, not necessarily which part failed. An ignition-failure code, for example, can come from an undersized gas line, a failing igniter, a dirty flame rod or a blocked vent. Note the exact code and when it appears before you contact us; it shortens diagnosis.
Scale, flushing and inlet filters
Mineral scale inside the heat exchanger reduces output and can trigger overheat codes. Water hardness differs by source, so if you know whether you're on the town system or a private well, mention it; flushing intervals depend on it. Units with isolation valves can be descaled in place; units installed without them may need valves added first.
Ask our plumbers to inspect the inlet filter screen, which can collect debris after water main work or well pump service.
Venting and condensate
Condensing tankless units produce acidic condensate that needs a working drain and, often, a neutralizer. A frozen or clogged condensate line on a cold January night will shut the unit down. Sidewall vent terminations also need clearance from snow, decks and windows.
Questions we hear
- Why does my tankless go hot, cold, then hot?
- Often called the cold-water sandwich, it happens when a fixture is turned off and on quickly. It can be normal in small amounts, but a worsening version points to flow sensor, gas supply or scale issues.
- How often should a tankless be flushed?
- It depends on your water hardness and usage. Ask our plumbers to recommend an interval after inspecting the heat exchanger and confirming your water source.
- Do you repair every tankless brand?
- Brand coverage and parts availability depend on the model. Share the brand and model so these can be confirmed before arranging work.
- Can I reset the error code myself?
- A single power cycle per the owner's manual is fine for a one-time code. If it returns, stop resetting and contact us. Never reset repeatedly if you smell gas.