Tankless units fail in a few predictable ways up here: scale from hard water, settings left at sea level, and cold-weather trouble. We start from the error code and the model, then fix it in a booked visit.
Flagstaff Water Heaters LLC · ROC 367669 · Arizona Registrar of Contractors · Licensed, bonded and insured
Every tankless unit reports its faults as a code. The code and the model number together usually point to the part before we arrive, so photograph both and send them when you call. We read codes against your model's own manual, never a generic list.
Minerals in hard water build up inside the heat exchanger. The unit runs hot, shuts itself off, or loses output. A descaling flush through the unit's service valves clears it, and the manufacturer sets how often it is due.
Many tankless units are set for elevation in the field, from the manufacturer's altitude table. A unit left at its factory setting burns wrong at Flagstaff's elevation. We check the setting on every visit. The sizing guide explains the code behind it.
Built-in freeze protection runs on electricity, so a winter power outage leaves the unit exposed. A unit that froze should not be run until it has been checked. The freeze guide covers what to do before and after.
A photo of the display and the rating plate tells us the model, the fault and the likely part.
A real appointment, Mon–Fri, 9:00 AM – 5:00 PM, planned around your day.
We confirm the fault at the unit and price the fix in writing before any work begins.
The part goes in, the heat exchanger gets descaled if it needs it, and the elevation setting gets checked before we leave.
Igniters, flame and flow sensors, fans and valves are repairs. A failed heat exchanger outside its warranty is often the point where replacing the unit makes more sense, and we will show you the numbers either way. One more case: a unit that is not rated for your elevation. One major maker's outdoor tankless line is certified only to 6,000 feet, below Flagstaff. No repair fixes that mismatch; an altitude-rated replacement does. The tankless installation page covers model selection, and tank vs tankless at 7,000 feet covers the choice itself.
Your model's manual sets the interval, and hard water shortens it. Annually is typical for most of our service area. On a first visit we look at how much scale comes out and tell you whether your water calls for more or less often.
A short burst of cold between uses is normal: the water sitting in the pipes cooled while the unit was off. Hot water that fades to cold during a shower is not normal. Scale, an undersized gas supply or a flow sensor are the usual causes.
Codes differ by brand and by model, so the reliable answer is in your unit's manual. Send us a photo of the code and the rating plate and we will read it for you before booking.
Many units are set for elevation in the field with switches or a menu setting, following the manufacturer's altitude table. If yours was installed without that step, it is burning as if it were at sea level. We check it on every visit.
Usually, if the fault is a sensor, an igniter, a fan or a valve. If the heat exchanger has failed outside its warranty, or the unit is not rated for your elevation, replacement is usually the better money. The written price comes first either way.
Mon–Fri, 9:00 AM – 5:00 PM · Serving Flagstaff, Williams and Winslow, plus the surrounding high country