Rinnai • Navien • Rheem • Expert diagnostics, descaling & repairs. Same-day service available.
It's 6 AM. You step into the shower expecting hot water and get a cold stream instead. You walk over to the tankless unit on the wall, see a flashing error code you don't recognize, and now you're standing in a towel trying to figure out who actually knows how to fix one of these things.
We do. And the reason that matters is that tankless water heaters are a different animal from tank-style heaters — they fail in different ways, they need different diagnostic equipment, and they reward technicians who actually understand the electronics, gas-air mixture, and flow dynamics involved. At Alliance Plumbing Services LLC, tankless repair isn't a side service. It's a specialty we've built deliberately, because the homeowners and businesses in St. Johns who chose tankless made that choice for a reason — endless hot water, lower long-term operating costs, smaller footprint — and that value evaporates the moment the unit isn't running.
The pages that follow walk through what we actually do when you call. No fluff, no upsell, no pressure to replace what can be repaired.
The most common call we get on a tankless unit is "it stopped producing hot water." Sometimes it's a hard error — a flashing code on the display, a unit that won't fire at all. Sometimes it's more subtle — water comes out warm but never hot, or hot water lasts a few minutes then drops out.
We diagnose by symptom pattern, not by guesswork, and we arrive with the tools to test each possibility on-site.
Our technicians carry the diagnostic tools to interface with Rinnai units directly, pull error history, and identify whether a current fault is a one-time event or a recurring pattern. Replacement parts stocked on our service trucks.
We pull error codes, run diagnostic cycles, service the recirculation pump and components, and descale the heat exchanger when buildup is the underlying cause.
The single most common preventable cause of tankless failure is scale buildup. We circulate a descaling solution and install isolation valves when needed so future service is easy.
Annual maintenance including descaling, filter cleaning, venting inspection, gas pressure verification, and combustion analysis.
Honest recommendations when repair no longer makes sense. Proper sizing, vent compatibility, recirculation options.
Rinnai, Navien, Rheem, Noritz, Bosch, Takagi and more.
We confirm make, model, and age so we can pre-stage the right parts.
Pull diagnostic data, error history, test gas pressure, flow, venting, ignition sequence and heat exchanger output.
Fixed price quoted before work begins. Most repairs completed same visit.
Full functional test under load. Unit performing perfectly before we leave.
Covers full diagnostic workup. Credited toward repair.
Isolation valves installed when needed.
Igniters, flame rods, flow sensors — quoted specifically.
Full service to keep your unit running efficiently for 20+ years.
Transparent pricing. No hidden fees. Invoice matches the quote.
The diagnostic visit itself usually runs 45 to 90 minutes. Repairs typically complete in the same visit when parts are available.
A properly maintained tankless unit in St. Johns should last 20 years or more... Units that get no maintenance often fail in 8 to 12 years.
It depends on the unit's age... We give you the actual numbers on both options in St. Johns rather than steering you toward one.
Each error code points to a specific fault category... Our diagnostic work in St. Johns always pulls the full history.
For most homes in St. Johns, annual descaling is the right interval... The unit's performance is the real indicator.
We service Rinnai, Navien, Rheem, Noritz, Bosch, Takagi, and most major tankless brands sold in St. Johns over the last 15 years.
One of the most common complaints... The most common cause we see in St. Johns homes is a low-flow showerhead combined with a partially clogged inlet filter...
The diagnostic sequence we run... Before authorizing any significant repair or replacement... get the flow situation properly diagnosed.
Tankless water heater issues in St. Johns usually have a specific, identifiable cause. Reach out to schedule a service visit today.
Click Here to Call (888) 466-2103