Last week I mentioned the main types of water heaters available and introduced the causes and possible remedies for a leaking P&T valve.  In this article I will discuss what to do if you find yourself without hot water.

When referring to loss of hot water in an RV, there are two main failure modes. The first is when no water flows when the hot water taps are opened, and the second is when only cold water flows from the hot water lines.

If you find that you don’t have water in the hot water lines, first verify that you have water in the cold water lines. If not, ensure the city water tap is turned on or water pump is turned on and functioning, there is water pressure in the line or water in the tank, and there are no kinks in the water supply hose. If there is water in the cold water lines but not the hot, the problem is likely either with the winterizing bypass valves or the one-way check valve(s) at the hot water tank. First make sure there is water in the hot water tank by briefly opening the P&T valve and ensuring water flows from the valve. Be very careful with this step, as the water will be very hot if the heater is functioning.  If there is no water in the tank, make sure the winterizing valves are in the normal (non-bypass) operating position. If this does not solve the problem, the issue may be a faulty check valve at the cold water inlet to the hot water tank. However, not all water heaters have check valves. The easiest way to verify the operation of the inlet check valve is to slightly loosen the water line entering the inlet check valve. This is the water line entering the bottom of the hot water tank. If there is water at the line entering the check valve, but not water in the tank, the check valve is faulty and should be replaced. Again, this assumes the winterizing bypass valves are properly set. If there is water in the hot water tank but no water in the lines downstream of that, verify operation of the outlet check valve by loosening the water line exiting the check valve. If there is no water there, the outlet check valve should be replaced.

If there is only cold water flowing when the hot water taps are open, this generally means that either the water heater is not functioning or the winterizing bypass valves are set to bypass mode. First briefly open the P&T valve and carefully check that hot water flows from the valve. Once again, this water may be very hot, so use caution! If no water flows at all, the winterizing valves are likely set to the bypass position. If cold water flows from the P&T valve, the water heater is either faulty, not turned on, has a tripped or faulty thermostat or ECO (energy cut-off), or has a problem with the energy source (propane or 120V electricity).  If you have verified that the water heater is not functioning, ensure that your other propane appliances work, you have AC power, and that none of the circuit breakers are tripped or fuses blown. Note that the hot water fuse may be on the water heater control board. Also check that the thermostat and ECO do not need to be reset or replaced. If none of these are the case, take your RV in to an authorized service center.

Remember to never turn on a water heater when the hot water tank is empty, as this can damage the electric heating element (in the case of 120V energy source), or the hot water tank (in the case of propane).

About the Author: 

Steve Froese, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.