Check the fixtures and demand
- Test more than one faucet or shower
- Confirm the temperature controller was not changed
- Run one hot fixture by itself
- Notice whether the problem appears only when several fixtures run
Start With These Checks
A few observations can help distinguish a fixture problem, a capacity issue, overdue maintenance or a tankless-system fault.
Check the heater's clues
- Look for an error code on the display
- Note whether the heater shuts down or keeps running
- Consider when it was last flushed or descaled
- Do not repeatedly clear a code that returns
If only one fixture is affected: the shower cartridge, mixing valve, aerator or showerhead may be the problem rather than the water heater.
When Scale May Be Contributing
Minerals can accumulate in the water side of a tankless heat exchanger. Depending on the unit and water conditions, scale may contribute to restricted flow, temperature fluctuation, noise or reduced heating performance.
What a flush does
A professional flush circulates an appropriate descaling solution through the water circuit, rinses the system and includes accessible inlet-filter cleaning. When scale is contributing to the symptom, maintenance may improve performance.
What a flush does not do
A water-side flush does not repair unrelated ignition, venting, combustion, sensor, control-board or failed-component problems. A displayed code or complete loss of hot water should be diagnosed rather than automatically treated as a maintenance issue.
When Diagnosis Is the Better Next Step
Schedule diagnosis when the symptoms point beyond routine maintenance.
Call when
- The unit produces no hot water
- An error code remains or returns
- The heater repeatedly shuts down
- The temperature problem began suddenly
- A recent flush did not solve the problem
Service may include
- Brand and model confirmation
- Error-code and symptom diagnosis
- Relevant water-flow and maintenance checks
- Applicable vent and condensate inspection
- An explanation before additional repair work
Safety: do not disassemble gas, combustion or sealed venting components as a homeowner troubleshooting step. If you smell gas or a carbon-monoxide alarm sounds, leave the area and contact the gas utility or emergency services from a safe location.
Rinnai Service Focus
Dustin has hands-on experience with Rinnai tankless systems, including Code 11 ignition complaints and Code 17 venturi blockages on applicable SENSEI models. He also diagnoses and services Rheem, Navien and Noritz residential tankless systems within his service scope.
Rinnai Code 11
Code 11 generally indicates that the unit attempted to ignite but did not establish a flame. The cause must be diagnosed before repair.
Rinnai Code 17
On applicable Rinnai SENSEI models, Code 17 identifies a venturi blockage. Service may include vent and condensate checks followed by venturi removal, cleaning, reinstallation and the applicable reset.
Not-Hot-Enough Questions
Will flushing make my tankless water heater hotter?
It may help when mineral scale is restricting water-side performance. If the cause is a fixture, capacity limitation, ignition fault, vent problem, sensor or component failure, a flush alone will not solve it.
What if only one shower is lukewarm?
When other fixtures produce properly hot water, the affected shower's cartridge, mixing valve or showerhead may be the more likely cause.
Do you diagnose the unit if a flush will not solve it?
Yes. Dustin provides tankless diagnosis and applicable repairs in addition to routine flushing.
Which brands do you service?
Dustin specializes in Rinnai and also works on Rheem, Navien and Noritz residential tankless systems.
How much is a routine tankless flush?
The standard flush is $150 for most normally accessible residential systems with working service valves. An October promotion reduces the standard flush to $125 when service is completed by October 31, 2026. Diagnosis, repairs, parts, missing or stuck valves and unusual access are quoted separately.
Not Getting Enough Hot Water?
Call or text Dustin to schedule tankless water heater service in Irvine.
Call (949) 371-6423