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RV water heater pressure relief valve dripping: normal expansion or repair?

A few drops after heating is different from a steady leak. The relief valve is a safety device, so the answer is not to cap it, plug it or ignore it.

Never plug a relief valve. Scalding water and pressure can injure you. Let the water cool before touching anything around the heater.

Why it drips

Water expands as it heats. RV water heaters need an air pocket to absorb some of that expansion. If the air pocket is gone, pressure can push water out of the relief valve. High city-water pressure, debris on the valve seat or a tired valve can do the same thing.

What to check first

  1. Confirm city water is regulated to a safe pressure for your RV.
  2. Turn off propane and electric heat and let the tank cool.
  3. Look for steady leakage versus a short drip during heating.
  4. Restore the tank air pocket using the water-heater manufacturer's procedure.
  5. If dripping continues, the relief valve may have debris or may need replacement.

When it is not the relief valve

Water near the exterior door can come from the drain plug, anode rod, bypass fittings, tank seam or plumbing connection. Dry the area and watch carefully before ordering parts.

Call for service if

The tank body leaks, the valve discharges hard, pressure is excessive, or you are not sure the heater is full before firing it. Empty-tank heating can ruin parts quickly.