RV water heater not working: what to check and what the repair costs

No hot water is one of the few RV problems where the odds strongly favour a cheap answer. The great majority of these calls across Mesa and the East Valley end at a $150 to $450 repair, and a fair number end at a part costing less than a tank of fuel. Replacement at $700 to $1,800 is the exception, not the rule.

Check this first (fifteen minutes)

If it runs on gas:

Confirm you have propane and that other gas appliances light. Obvious, and it is the answer more often than anyone admits.
Listen at the outside access panel. You should hear the gas valve click, then a series of sparks, then a whoosh. Sparks with no whoosh means gas is not arriving or the burner is blocked. No sparks at all means the board or the electrode.
Look into the burner tube with a torch. In Arizona, mud dauber wasps build in that tube, and a blocked tube means the flame cannot establish. This is one of the most common causes, and it is a cleaning rather than a part.
Find the ECO / high-limit reset. Usually a small button behind the outside panel. A tripped high limit locks the unit out, and it is often what people mean when they say the heater “just stopped”.

If it runs on electric:

Check the switch inside and the breaker. Many rigs have an interior switch for the electric element that is easy to leave off.
Make sure the tank is full of water. Running an electric element in an empty tank burns it out within minutes, and that is the single most common way people destroy an element after winterising or after a dry camp.

What is usually wrong

What you observe	Likely cause	Fix and cost
Sparks, no flame	Blocked burner tube, often a wasp nest	Clean and service, $150–$300
No spark at all	Electrode, control board, or a bad ground	$200–$450
Lights, then goes out in seconds	Thermocouple or flame-sense circuit	$150–$350
Works on gas, not on electric	Failed heating element or its thermostat	$200–$450
Works on electric, not on gas	Gas valve, regulator pressure, or burner	$200–$500
Water lukewarm on both	Thermostat, or a tank half full of sediment	$150–$450
Rusty water, weeping tank	Tank corrosion, often a neglected anode	Replacement $700–$1,800
Steady stream from the relief valve	Lost air gap or a failed valve	Often under $200

These come from the pricing page and sit on top of the $75–$150 trip fee and $125–$190 hourly labour.

The Arizona specifics

Wasps. Mud daubers are relentless here and they love the burner tube of a water heater and the furnace intake. Rigs that sit through the summer in a storage lot come back with nests in both. Screens over those openings cost a few dollars and prevent an annoying share of no-heat calls.

Hard water. East Valley municipal water is hard, and a tank that has never been flushed collects a sediment layer that insulates the bottom of the tank from the burner. The symptom is lukewarm water and a heater that runs constantly. Flushing a tank takes twenty minutes and is worth doing every season.

Sitting dry. A rig stored empty through a Phoenix summer bakes the tank and every seal in the system. Do not switch the electric element on before you have confirmed the tank is full. That one mistake accounts for a meaningful number of dead elements every October.

Tank or tankless, if it comes to replacement

If the tank is perforated, the decision is which way to replace it. Tank units are cheaper, simpler, and take a known footprint. Tankless units give endless hot water and take a bigger gas and electrical demand, and they are less forgiving of low water pressure. In a rig that mostly sits at a resort with full hookups, a tankless is a genuine comfort upgrade. In a rig that dry camps, it often is not. Pick the one that fits the way you actually use the rig rather than defaulting to the bigger invoice.

What to expect on the call

Tell us the brand off the outside panel, whether it fails on gas, electric, or both, and what you hear when it tries to light. That conversation often ends with a part and an appointment rather than a diagnosis visit. Water heater calls happen at your resort space, storage lot, or driveway across Mesa, Apache Junction, Gilbert, Tempe, and Queen Creek.

Frequently Asked Questions

My RV water heater will not light. What is the usual cause?

On a gas water heater, the top three are a dirty or spider-blocked burner tube, a failed thermocouple or electrode, and a tripped high-limit (ECO) switch. All three are inexpensive. Mud dauber wasps building in the burner tube is genuinely one of the most common causes in Arizona.

How much does RV water heater repair cost?

$150–$450 for the common repairs: thermocouple, element, anode rod, thermostat, or a burner cleaning. A full replacement runs $700–$1,800 installed depending on whether it is a tank or tankless unit. The diagnosis comes first, because most no-hot-water calls end in the cheaper column.

Water is dripping from a valve on the outside of the water heater. Is it broken?

Probably not. That is the pressure and temperature relief valve, and a small weep after the water heats is normal as the tank pressurises. A steady stream is not, and usually means the air gap at the top of the tank has been lost, which is a five-minute fix, or the valve itself has failed.

Do I need to replace the anode rod?

If you have a Suburban with a steel tank, yes, roughly annually. That rod exists to corrode instead of your tank. Atwood and some newer tanks are aluminium-clad and do not use one. Getting this wrong is how a perfectly good water heater tank ends up perforated.