Open 24/7 for emergencies
A Rinnai tankless water heater repair starts with the $99 diagnostic, and a new Rinnai is $8,886 to $10,486 installed, permit and haul-away included. We install Rinnai, so a code 11 or an LC on the controller tells us where to look.
From about $148 a month at 0% APR for 60 months, the whole price financed, on approved credit. How financing works
Get your price in writing
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Rather talk now? (703) 997-9757
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Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceOften same-day, and we will tell you honestly when we can get there.
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The price is settled before the workYou see the number in writing before anything is taken apart
Read your own Rinnai
The things people describe on the phone about a Rinnai, and where each one points.
Write the number down. 11 is no ignition and 12 is flame failure, and both often come back to the gas: Rinnai’s checklist starts with the gas being on, propane in the tank, and a gas line, meter and regulator sized right. 10 means the air supply or exhaust is blocked, or on a condensing model the condensate trap is full.
The hot water left in the pipe runs out, then you get a few seconds of cold while the burner fires back up. A Rinnai needs 0.4 to 0.6 gallons a minute to light and 0.26 to keep running, so a trickle from one tap can let it drop out. The RXP and REP have a recirculation pump built in, and the RXP’s learns your hot water use over seven days.
Check the flow first: below 0.26 gallons a minute the burner shuts off, then lights again when you open the tap wider. After that it’s the inlet filter, scale, or the gas, and Rinnai says an undersized gas line stresses a tankless and can shorten its life. We clean the filter and check the gas before anyone talks about parts.
Start with the in-line screen filter on the cold water inlet: Rinnai says check it periodically and clean it. Scale building up inside the heat exchanger narrows things too, and that’s the descale.
LC means scale is building up in the heat exchanger and it needs a flush; newer units lock out, and a reset buys about 70 hours. SS is a service reminder set at install, telling you it’s time. Rinnai calls for a yearly flush on a home unit once the water is 4 grains per gallon or harder, and scale damage isn’t covered by its warranty.
With power and gas on, a Rinnai protects itself from freezing: an indoor unit down to -22°F, an outdoor one to -4°F out of the wind. If the power goes out in a freeze, Rinnai says drain it, because freeze damage isn’t covered. Leaking after a cold night? Shut off the water to the heater and call.
The controller
A Rinnai with a problem shows a number on the controller. Write it down with the model from the rating plate, because a few numbers mean different things on different lines.
Rinnai’s code book gives these the same meaning on every line, give or take the wording.
| Code | What it means | What to do |
|---|---|---|
| 10 | The air supply or exhaust is blocked; on a condensing unit, the condensate trap may be full | Check the vent caps outside for a blockage, then call: the condensate line and air filter get checked too |
| 11 | No ignition: the heater didn’t light | Check the gas is on, and on propane that there’s gas in the tank |
| 12 | Flame failure: it lit, then lost the flame | The same gas checks as 11. If it keeps coming back, call |
| 16 | The outlet water went over 203°F (the V Series calls it a warning) | Leave it off and call |
| 19 | An electrical grounding fault | A wiring check |
| 61 | The combustion fan | A fan repair |
Source: Rinnai Troubleshooting TWH Diagnostic Codes, 100000652. Codes vary by model and control board: the chart printed on your unit, or its manual, is the final word.
Check the rating plate for the line first: a SENSEI (RX, RXP) and the non-SENSEI units (RE, REP, V, RUS) don’t always mean the same thing by the same number.
| Code | What it means | What to do |
|---|---|---|
| LC (LC0 to LC9, 00) | Scale building up in the heat exchanger | A flush. Newer units lock out; a reset buys about 70 hours |
| SS | Service soon: a flush reminder set at install | Book the flush. On a SENSEI RX it’s set for 6, 12 or 24 months |
| 14 | Overheat. SENSEI RX: the heat exchanger; RE and V: the thermal fuse | Call. Rinnai’s checks include hot spots on the heat exchanger from scale |
| 25 | SENSEI RX: the condensate pump accessory’s safety switch | It only shows with a condensate pump installed: check the pump, then call |
| 32 | RE: the outgoing water temperature sensor | Scale on the sensor is one cause: a cleaning or a new sensor |
| 52 | SENSEI RX: the gas valve. RE and V: the modulating solenoid valve signal | A gas valve repair |
| 63 | SENSEI RX on a recirculation loop: recirculation flow too low | The loop needs more than 0.4 gallons a minute: a pump or loop check |
| 72 | SENSEI RX: the flame rod. RE and V: the flame sensing device | On an RE, Rinnai says check the flame rod for carbon |
| 79 | RE, V and other non-SENSEI units: water found in the cabinet | Shut off the water to the heater and call a licensed pro |
Source: Rinnai SENSEI RX and RE technical sheets, linked from Rinnai’s product pages. Codes vary by model and control board: the chart printed on your unit, or its manual, is the final word.
What it costs
A repair is priced after the $99 diagnostic, because the fix depends on which part failed. A new tankless water heater is a range we can print, everything in.
Diagnostic visit
$99
The code read, the fault found, and the repair priced in writing. You approve it or you don’t.
A new Rinnai tankless
$8,886 to $10,486
or $148/mo at 0% APR for 60 months
One condensing tankless water heater, sized for the house. The permit and haul-away included.
Monthly figures: 60mo @ 0% APR on each starting price, the whole price financed, on approved credit. Longer plans lower the payment and cost more in total. The lender sets the final terms. How financing works
The yearly descale is its own visit: tankless water heater descaling. Comfort+ members get the $99 diagnostic included in the visit, 15% off any service, and 50% of each repair bill banked toward replacing that system, up to $1,500. How Comfort+ works.
Fix it or replace it
Rinnai prints the manufacture date on the rating plate. The serial number won’t tell you.
Rinnai doesn’t publish a way to read the age from the serial number, and the letter charts on other websites don’t fit Rinnai’s own serials, so skip them. The manufacture date is its own line on the rating plate; on an RX or RXP the plate is on the left-hand side of the heater.
Rinnai says its tankless water heaters last up to 20 years, depending on water quality, use and maintenance (Rinnai).
Gas or propane tank instead
$3,379 to $5,485
or $56/mo at 0% APR for 60 months
50 or 75 gallon on a flue you already have. Installed.
Power vent tank instead
$5,957 to $7,494
or $99/mo at 0% APR for 60 months
Gas or propane, a fan and PVC out a side wall. Installed.
Electric tank instead
$2,757 to $5,493
or $46/mo at 0% APR for 60 months
50 or 80 gallon. No flue, no gas line.
Monthly figures: 60mo @ 0% APR on each starting price, the whole price financed, on approved credit. Longer plans lower the payment and cost more in total. The lender sets the final terms. How financing works
Want your own number before anyone comes out? The water heater estimator prices your house in a few questions.
Our Virginia Class A contractor license, 2705192276, on the side of the van. Rinnai recommends a licensed contractor for the install.
Why we install Rinnai
Rinnai makes condensing and non-condensing tankless water heaters, with a pump and without.
The warranty
The model line sets the terms, and registration sets the labor.
Rinnai’s terms: Rinnai’s warranty page. We read the model and the plate date before ordering anything.
Where we work
Out of Chantilly and Ashburn, across six counties. Pick your town for its own water heater page: the houses there, the county’s permit rules, and the same prices.
Keep reading
Every make we work on, in one place: the brands we repair.
The system we put in first
Built to take a beating. Put in by our crew.
Heat lamps, snow and rain on one outdoor unit: that’s Trane’s own film. We’re a Trane Comfort Specialist, on Trane’s own dealer locator, and when you pick a Trane, our crew puts it in.
Films: Trane’s own.
Asked on the phone
A repair starts with the $99 diagnostic: we read the code, find the part, and price the fix in writing before any work. A new Rinnai tankless is $8,886 to $10,486 installed, everything in, and going back to a gas tank is $3,379 to $5,485. From about $56 a month at 0% APR for 60 months, the whole price financed, on approved credit. How financing works
11 means no ignition: the heater didn’t light. Rinnai’s checklist starts with the gas: is it on, is there propane in the tank, and are the gas line, meter and regulator sized right? If the gas checks out and 11 keeps coming back, call.
Scale is building up in the heat exchanger and it needs a flush. Newer Rinnai units lock out on LC, and a reset buys about 70 hours before it locks out again; older ones kept running. Rinnai calls for a yearly flush once the water is 4 grains per gallon or harder.
Yes. We install Rinnai and Navien tankless water heaters, and Rheem, A. O. Smith and Bradford White tanks. We repair any Rinnai tankless on natural gas or propane, whoever put it in. Rinnai doesn’t make an electric tankless.
No. CPSC has never recalled a Rinnai tankless water heater. Rinnai’s recalls were I-SERIES Plus boilers in 2025 and EnergySaver wall furnaces in 2008.
Rinnai says up to 20 years, depending on water quality, use and maintenance. Skipping the flush damages the heat exchanger, Rinnai says, and that damage isn’t covered. Our guide to tankless water heater maintenance walks through the yearly descale.
Get the hot water back
No hot water or a code that won’t clear: call (703) 997-9757, 24/7. Not that urgent? Send the form at the top with the number on the controller, and the office calls or texts you back.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
Virginia Class A contractor license #2705192276
Prices are SwiftPro’s installed ranges with the permit and haul-away. Yours is quoted in writing before any work.
Rinnai is a registered trademark of Rinnai Corporation, used under license by Rinnai America Corporation.