On the covered Rinnai tankless water heater, 65 means a fault in the water flow control. Rinnai states that the water flow control valve may have failed to close during the bath fill function. First, if water keeps flowing during a bath fill, shut off the water at once.
Differential
Likely causes of “Rinnai tankless water heater code 65”, and how to tell them apart
- 1
The water flow control failed to close
What separates it Water keeps flowing during bath fill
How to confirm Shut off the water at once
- 2
A faulty valve or sensor
What separates it The resistance is out of range
How to confirm Technician measures it
- 3
A wiring fault
What separates it Intermittent faults
How to confirm Technician inspection
- 4
Scale or debris in the valve
What separates it The valve sticks
How to confirm Flush and filter
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether the bath fill function was in use
- Whether water kept flowing
- Whether the code returns
Try in this order
0 of 8 completedWhat to do first
ReversibleIf water keeps flowing during a bath fill, shut off the water at once.
Correct only the documented fault domain
ReversibleRinnai directs measuring the resistance of the water flow control. If the valve failed to close during bath fill, immediately turn off the water, discontinue the bath fill function and contact a licensed professional to service the appliance.
Shut off the water
ReversibleIf it will not stop.
Stop the bath fill function
ReversibleUntil serviced.
Reset the power once
ReversibleAfter the water is off.
Do not use the function
ReversibleAgain.
Note the code
ReversibleAnd model.
Call a licensed professional
ReversibleTo service it.
Model-specific
What is true of this model and not of its siblings
- The flow control valve
- The water flow control opens and closes to meter water, such as the volume for a bath fill. If it fails to close, water can overflow a tub.
- Rinnai's advice
- Rinnai says to measure the resistance of the water flow control, and, if the valve failed to close, to turn off the water immediately, stop the bath fill function and contact a licensed professional.
- Practical care
- Do not leave a bath filling unattended, and know where your water shut-off valve is.
- What bath fill needs
- The bath fill function lets the heater deliver a set volume of water at a set temperature to fill a tub. To do that the water flow control valve opens, meters the water and closes. Code 65 warns that the valve may not have closed when it should.
- Why Rinnai is cautious
- A valve that fails open can overfill a bath and flood a bathroom, so Rinnai's advice is to turn off the water at once, stop using the function and call a licensed professional. Never leave a bath filling unattended.
- Everyday use
- Until the valve is serviced, use the taps normally and avoid the bath fill function. Know where the water shut-off to the heater is, so you can close it quickly.
- Locating your shut-off
- Find the water shut-off valve for the heater now, before you ever need it, and label it. In an emergency, closing it stops both the flow through the valve and any overflow from a tub.
Stop boundary
When this stops being a self-service repair
- !If water keeps flowing during a bath fill, turn off the water immediately
- !Stop using the bath fill function
- !Contact a licensed professional
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What does 65 mean on a Rinnai tankless water heater?+
A fault in the water flow control. Rinnai states that the water flow control valve may have failed to close during the bath fill function.
What if water will not stop?+
Shut it off at once.
Which function is involved?+
Bath fill.