RV Water Heater Repair: Fixing the LP Tubing Connections

What You'll Need
Electronic leak detector, bubble test solution or a spray bottle filled with soapy water
Two wrenches, channel lock pliers or crescent wrenches
Copper tubing cutter
45 degreeflare tool
Copper tubing
Flare nut

A key component of RV water heater repair is inspecting the LP gas connection. Typically, RV LP gas systems use copper tubing run from a black iron manifold system that feeds all LP gas appliances in the RV. In some cases, flexible tubing may be used to connect to your water heater. This article covers copper tubing connections.

Step 1 - The Smell Test

LP gas is treated with an additive that renders a distinctive smell. A strong rotten-egg odor emanating from the hot water heater is a first indicator that the connections may be faulty.

Step 2 – Check for Loose Fittings

Your problem may be as simple as a loose fitting. Tighten the connection and check for leaks. 

Step 3 - Leak Test

Use an electronic leak detector or a low tech “bubble test”. Bubble test solutions are available for purchase, but in a pinch, use liquid dish detergent mixed with water in a spray bottle. Do not use ammonia or bleach based products, as these will corrode copper tubing and fittings.

Spray the solution onto the LP connection then observe. If you see bubbles forming you have a leak.

Step 4 - Safety First

Turn the gas off. Open the RV’s windows and doors so that the area is well ventilated. Do not proceed until you are certain the gas is off and the area well ventilated.

Step 5 - Remove the Old Fitting

Using two wrenches, one for the flare nut and another for its mate on the water heater, loosen the old fitting and remove the copper tubing from the water heater. Check to be certain that you have enough slack in the tubing to reconnect the water heater after your repair. If not, it will be necessary to replace the tubing from the gas manifold to the water heater.

Step 6 - Cut the Tubing

Using a tubing cutter, remove the flare and any damaged tubing. Inspect for burrs and for a deformed end (flattened or oblong). Sand or file the burrs as needed, but if the tubing is deformed, cut that section off and start over. A perfectly round tube is necessary for a good flare (see below) and a leak-free fit.

Step 7 - Flare the Tubing

Place the new brass flare nut onto the tubing, thread side facing the water heater. Now use a 45 degree flare tool to flare the copper tubing. Inspect the flare to ensure it is not deformed by looking into the tube. If the flare appears circular and the center of the tube is centered with the flare, you’ve done a good job. If not, cut it off and begin again.

Step 8 - Connect the New Fitting and Check for Leaks

Connect the new fitting to the water heater, then turn on the LP gas. Using the same methods as described earlier, check for leaks.