RV Water Heater Not Heating Water? Here's Why
Quick Answer
If your water heater is running but not heating, check that the thermostat is set above 120°F and give the tank 45 minutes to heat from cold. If it's still cold, the electric heating element is likely burned out, gas pressure is too low, or the thermostat itself is broken. Most cases require a technician visit to confirm the element or component needs replacement.
Your RV water heater is turning on and running—you can hear it or smell propane—but the water coming out of your taps is still cold. This is different from a heater that won't turn on at all, and the causes are narrower. Usually it's a burned-out heating element, insufficient gas pressure, a thermostat set too low, the system short-cycling and not staying on long enough, or a tank that's simply too small for your usage. This guide shows you how to diagnose which one is happening and what you can fix yourself.
Heating Element Burned Out (Electric Mode)
If your RV water heater works fine on gas but produces no heat when switched to electric mode, the heating element has burned out. The heating element is a sealed electric resistor that heats water directly; when it burns out, it's an open circuit and won't conduct electricity. You can test this: turn on the water heater in electric mode and listen for a gentle hum near the tank—if there's no sound or vibration, the element is likely dead. If you have a multimeter, a technician can measure resistance across the element's terminals; no continuity means it's burned out. Heating element replacement is a straightforward job for a technician ($100–$200 for the part, $150–$300 for labor). The element is screwed into the tank, so accessing it requires draining some water and opening a service panel. Most elements last 5–10 years depending on water hardness and mineral deposits. Hard water causes mineral scaling on the element, which insulates it and causes it to burn out faster. If you live in an area with hard water, descale your element every 2 years (use a weak vinegar solution or commercial descaler) to extend its life. Don't attempt to remove the element yourself unless you're plumbing-savvy—it's pressurized and can spray hot water.
Gas Pressure Too Low for Burner to Ignite
If your gas stove has weak flame or won't ignite at all, your RV's propane system pressure is too low. This happens when the regulator (the device that controls propane pressure from the tank) is faulty, the supply line has a slow leak, or propane volume is simply running low. When propane pressure drops below the minimum threshold needed for the water heater burner (typically 10–12 inches of water column), the burner won't stay lit or won't light at all. Test this: check your stove—if the burner flame is weak or only lights when you hold the igniter button, pressure is low. If the stove won't light at all, pressure is very low. First, confirm your propane tank isn't simply running empty—check the gauge on the exterior. If it reads below 1/4 tank, refill it; propane pressure drops significantly as the tank empties. If the tank is still 1/2 full or more, the regulator might be stuck in a low-pressure state. Try closing the propane tank valve for 5 seconds, then reopening it; this sometimes resets the regulator. If pressure doesn't return to normal, the regulator needs professional inspection or replacement ($100–$200). A regulator service technician can test the pressure with a gauge and determine if replacement is needed. Until then, use electric mode for your water heater if available.
Thermostat Set Too Low or Not Communicating with Burner
The simplest reason your heater doesn't heat is the thermostat dial pointing to the lowest setting or 0°F. Check your control panel: if the dial is rotated all the way counter-clockwise, or if a digital display shows a very low temperature target, turn it up to 130–140°F and wait 5 minutes. The burner should kick on and you should feel heat rising from the tank. If adjusting the thermostat doesn't turn on the burner, the thermostat itself may have failed and isn't sending the "heat" signal to the control board. A faulty thermostat won't respond to adjustment and the burner won't cycle on at all. This requires professional replacement ($80–$150 part, $100–$200 labor). Before assuming the thermostat is dead, try the power reset: turn off the heater, trip the breaker for 30 seconds, and restore power. This sometimes fixes a stuck thermostat signal. If the reset doesn't help and you've confirmed all other components (power, propane, igniter) are working, the thermostat or its wiring is the culprit.
Short Cycling: Heater Turns On Then Off Too Quickly
Some RV water heaters have a problem where they ignite, run for 30 seconds or a minute, then shut off without heating the water adequately. This is called short-cycling and is usually caused by a faulty thermostat or thermistor that signals the burner to shut off prematurely. The thermostat might be reading false temperature signals (the tank is cold, but the sensor reports it's hot), so the control board shuts down immediately. Another cause: the pressure relief valve is opening too soon (venting heated water before it accumulates), causing the tank to never reach target temperature. Test short-cycling: turn on the heater and listen. If the burner ignites, runs briefly, then clicks off, and never runs again for an hour, short-cycling is happening. First, try resetting the control board by cycling power (turn off heater, trip breaker, wait 30 seconds, restore). If that doesn't help, the thermistor (temperature sensor inside the tank) or the relief valve might need adjustment or replacement. This is a technician call; they can monitor the heating cycle with a gauge and pinpoint whether the sensor or valve is the culprit ($100–$300 repair).
Tank Too Small for Your Hot Water Demand
RV water heaters come in various sizes: 6, 10, 20, or 40 gallons are common. If your heater is running fine but you run out of hot water quickly (after one shower or filling a sink), your tank is simply too small for your usage pattern. This isn't a failure—it's a design limitation. Most RVs ship with 6–10 gallon tanks, which are adequate for boondocking and conservation, but if you're parked at a campground with hookups and want unlimited hot water, you'll exhaust a small tank in minutes. You can't "fix" a small tank other than heating water faster (which the burner is already doing), so your options are: (1) use less hot water (shorter showers, cold-water rinses), (2) allow longer heating time between uses (the heater keeps the tank topped up), or (3) upgrade to a larger water heater if you're planning a long campground stay. Larger RVs sometimes have 20–40 gallon tanks, which provide more cushion. If you're considering an upgrade, factor in the cost of a new heater ($400–$1200) and installation against how much time you'll spend in your RV. For most boondockers, a small tank is fine; it encourages water conservation. For full-time RV living or a family of four, a larger tank is worth the investment.
When to Call a Pro
Call a technician if the heater is running but the electric heating element isn't warming water, if gas pressure is too low and the regulator needs testing, if the thermostat won't respond to adjustments, or if short-cycling persists after a power reset. Element replacement and regulator testing require specialized knowledge.
Frequently Asked Questions
How long does it take an RV water heater to heat a cold tank?
From completely cold, most RV water heaters take 30–60 minutes to reach 120°F, depending on tank size and ambient temperature. Larger tanks take longer; if the weather is very cold, add more time. In summer, a 10-gallon tank might be hot in 20 minutes. Always give the heater at least 45 minutes before concluding it's not working.
Can I clean mineral deposits off my electric heating element?
Yes, in many cases you can extend element life by soaking it in a weak vinegar solution (1 part vinegar, 3 parts water) for 2–4 hours to dissolve mineral buildup. This doesn't require removing the element from the tank. Pour the vinegar through the hot water tap or through the drain plug area. This is worth trying if you suspect mineral scale is reducing heating efficiency.
What's the difference between propane pressure being low vs. the tank being empty?
Low pressure means propane is present but the regulator is restricting flow, causing weak flames or ignition failure. An empty tank has zero pressure. Test by checking your tank gauge (if empty, refill immediately) and by trying to light your stove (weak flame indicates low pressure; no flame means either very low pressure or completely empty). A pressure gauge test by a technician can give you the exact PSI.
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Last updated: 2026-02-18