Why is my RV water heater not working?

When this usually happens

Most calls come when outdoor temperatures fall to around 35°F (1–2°C). At this point, the water in the supply line isn’t frozen, but it’s cold enough to disrupt the heater’s operation.

Because water still flows normally, it’s easy to assume the heater has failed, when in reality it’s reacting to the low inlet temperature.

Why cold inlet water causes the issue

Water heaters in RVs are designed to raise water temperature by a specific range. When the inlet water is already near freezing, the heater can’t make up the difference quickly enough.

This may trigger safety shutdowns or simply result in water that never reaches hot temperature.

How to prevent the problem

To restore normal function, preheat the incoming water before it reaches the heater.

• Wrap heat tape (or a thermostatically controlled heat cable) around the cold-water line leading from the spigot to the water heater.

• This keeps the water above freezing and allows the heater to operate as designed.

Important:

• Do not apply heat tape directly to the water heater or the hot-water outlet line.

• Use only heat tape rated for exterior plumbing and plug it into a grounded outlet.

• Add insulation over the wrapped line for better efficiency in freezing weather.

Where to find heat tape

RecPro does not sell heat tape, but it’s commonly available at most hardware or home improvement stores.

It’s best to install it before a cold snap because once the line is already cold, the heater may not recover quickly.

Summary

If your RV water heater stops heating when it’s cold outside, it’s likely because the incoming water is too cold, not because the heater is defective.

Keeping the inlet line warm with heat tape prevents future shutdowns and protects your system from possible damage.