RV Water Heating Systems
Know Your Brand (Dometic/Atwood vs. Suburban) How you drain and protect your water heater depends entirely on the manufacturer. Never mix up the replacement parts for these two dominant brands:
Adding a hot water system essentially doubles the plumbing inside an RV. Beyond the main pump and city water valve, you have the water heater tank and a completely separate set of hot water pipes running to each sink and shower.
The water heater consists of an insulated storage tank (usually holding six to ten gallons) and a propane gas burner used to heat the water. Depending on the model, the storage tank is made of either aluminum or porcelain-lined steel.
Steel tanks use an anode rod
to prevent the tank itself from rusting. The corrosive elements in the water attack and "eat up" this sacrificial anode rod rather than the steel walls of the tank. These rods should be inspected and replaced annually. Aluminum tanks are naturally corrosion-resistant and do not require an anode rod.
Additional water heater options in some motorhomes include electrical heating elements and "motor aid" systems, which use the vehicle's engine heat to warm the water while you drive.
As cold water in the tank heats up, it expands and increases the overall water pressure in your plumbing. Because RV water systems are only designed to handle about 45 PSI, this added pressure can cause the temperature/pressure relief valve to "weep" or create leaks elsewhere.
To help prevent this, you should always use a water pressure regulator when hooking up to a pressurized city water source. Furthermore, the water heater is designed to trap a pocket of air at the top of the tank to act as a cushion. This air pocket compresses as the water heats and expands, absorbing the excess pressure.
Over time, this air pocket can be absorbed into the water due to the motion of the vehicle and normal use, so it occasionally needs to be restored.
To restore the air pocket, follow these steps:
- Step 1:Turn off the water pump or city water supply.
- Step 2:Open a hot water tap to reduce the water pressure to zero.
- Step 3:Remove or open the water heater drain plug or valve.
- Step 4:Allow the water heater to drain and flush it by running water through it for several minutes.
- Step 5:Insert the plug or close the drain valve and re-fill the water heater tank until the water appears at the opened hot water faucet.
Add an Accumulator Tank
Another solution would be to add an accumulator to the system. An accumulator tank is basically a sealed tank in the water system that has an air pocket to absorb extra pressure.
See also: RV Water Heater Dripping?.