RV water heater not getting hot enough
What this usually means
There is a difference between no hot water at all and hot water that runs out quickly, and it is worth being precise. No hot water at all, particularly on the first trip of the season, is very often a bypass valve still set for winterising — the tank is simply empty. Hot water that runs out fast is usually sediment occupying the volume that should hold it.
Check this first
Check the water heater bypass valve position. If the coach was winterised and the bypass was never returned to the run position, the tank has no water in it and the heater will appear completely dead. It is free to check and it is right more often than anything else on this page.
Stop-work system
Gas water heaters involve a propane burner and an exhaust path. Combustion appliances are a technician job.
Nothing below is a repair instruction for this system. What follows is what to observe and record — the work itself belongs to a technician.
Most likely causes
Ordered by how often each one turns out to be the answer, with the tell that distinguishes it.
Bypass valve still in the winterising position
most commonPlenty of cold water, no hot water at all, first trip of the season.
Sediment reducing capacity
commonHot water runs out after a minute or two; recovery is slow.
Failed electric heating element
commonWorks on gas but not electric.
Thermostat out of adjustment or failed
commonWater is warm but never properly hot in either mode.
Gas side not firing
commonWorks on electric but not gas — a combustion-side fault.
Consumed anode rod, on tanks that use one
commonOverdue service; often accompanied by sediment and a rotten-egg smell.
What you can safely check
- 01
Check the bypass valve first, every time
A bypass left in the winterising position routes water around the tank so it never fills. It presents as a completely failed water heater and costs nothing to rule out.
- 02
Note which mode fails
Gas only, electric only, or both. Both modes heat the same tank, so a failure in one alone eliminates the tank and points at that mode’s components.
- 03
Identify your tank material before buying an anode rod
Steel-lined tanks use a sacrificial anode that is consumed and replaced. Aluminium-clad tanks are not designed for one, and fitting an anode to them causes damage rather than preventing it. Confirm your model first — this is the most common expensive mistake made on RV water heaters.
- 04
Note how quickly the hot water runs out
Immediately versus after several minutes distinguishes an empty or bypassed tank from a sediment problem.
What needs a technician
Element and thermostat replacement, gas-side work of any kind, tank flushing, anode service and assessing whether the tank itself is at end of life. Energising an electric element in a dry tank destroys it almost immediately, which is why tank status is confirmed before power is applied.
Parts typically involved
So you know what a quote should be naming. We publish no prices — real costs vary by market, season and technician, and a number we invented would look authoritative and help nobody.
- Electric heating element
- Thermostat
- Thermal cutoff (ECO)
- Anode rod, on steel tanks only
- Bypass valve kit
- Complete water heater, at end of life
When to stop troubleshooting
- You are about to switch on electric mode without confirming the tank is full
- There is soot at the exterior vent or a gas smell
- The pressure relief valve is discharging repeatedly
Can you still travel?
Comfort rather than safety, and driving is unaffected. If the tank is empty because of the bypass, that is fine for travel — just do not run the electric element until it is filled.
Common questions
- Should I put an anode rod in my RV water heater?
- Only if your tank is the type that takes one. Steel-lined tanks are designed around a sacrificial anode that is consumed protecting the tank and replaced periodically. Aluminium-clad tanks are not, and fitting an anode to one causes damage rather than preventing it. Confirm your model before buying anything — this is the most consequential single fact about RV water heaters.
- Hot water runs out after two minutes. Is the heater failing?
- Often it is sediment rather than failure. Accumulated sediment takes up volume that should be holding hot water and insulates the heating surface, so the tank both holds less and recovers more slowly. Flushing is part of routine service and frequently restores most of the lost capacity.
- Why does my hot water smell like rotten eggs?
- Generally a reaction between the water supply and the anode rod in a steel tank rather than contamination. It is addressed through flushing, sanitising and sometimes a different anode material. Unpleasant rather than hazardous, but worth dealing with because it indicates conditions inside the tank worth looking at.
Related failures
For the whole system rather than this one symptom, see RV water heater repair.
Next step
Work through structured triage for this system and you will end up with a written service brief: what you observed, in what order, and what has not been established yet. It is the document that lets a technician quote properly instead of guessing on arrival.
Being straight about what this is. No technician is signed to any territory yet — not one. We do not match you, dispatch anyone, or promise a call. What you get is the brief, and a request form that copies it to us so we know the demand is real. If you need someone today, take the brief and send it to a local technician directly; it works just as well that way.