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Ask Dave: Why won’t the water heater drain plug come out?

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses removing a stuck water heater drain plug.

Dear Dave,
I’m trying to winterize the water heater and can’t get the plug out. Sprayed it and it still won’t budge. I sure don’t want to break the heater. Is there another way to get the water out? It’s a Suburban water heater in a 1997 Allegro Star. Thanks. —Eloise

Dear Eloise,
The drain plug you are trying to get out of your Suburban water heater is also an anode rod, so it might be stuck due to rust or even the anode rod deteriorating and crusting!

You can see the rusting on this unit that is new at a dealership. As the water inside the tank heats up to 140+ degrees and cools down dozens of times, it will also naturally “seat” or stick, as well. Atwood uses an aluminum tank and has a plastic plug which doesn’t rust. But it is still sometimes difficult to remove as the plastic almost melts to the threads of the tank! And it is easier to strip.

This is what a new anode rod looks like which has a steel head and threads. Start with a good 6-point socket that is correctly sized as these typically have thicker walls. That reduces the flexing and is less likely to slip than the 12-point sockets. Liberally spray the exposed threaded areas with a good rust penetrator such as PB B’laster, one of my favorites. It may take several applications and waiting time but be patient.

It also is a good idea to turn the water heater on and let it get to operating temperature, as heat always helps loosen threads. Be careful not to take the anode rod out with hot water inside the tank. Also, do not start the water heater if there is not water in it, especially in the 120-volt mode, as you will short out the heating element!

Some people I know have used a small butane torch to heat the head and threads. However, I have always been able to “persuade” the nut out with patience, water heat, and a lot of penetrating spray. But sometimes a light tap of a hammer on the breaker bar head while applying pressure is required.

If all else fails, there are other ways to get the water out of the tank. However, you still need to examine the anode rod each year and replace it as needed. Otherwise, the tank itself will start to deteriorate.

Forced air

One method of winterizing is to use an air compressor hooked to the city water fill and open faucets and blow out the water in the system. This could work to get the water out of your water heater tank, as well. Hook up an air compressor and dial it down to about 40 psi and open the hot water faucets throughout the unit. It will eventually drain most of the water out of the water heater tank if you have already drained all the water out of the fresh water tank. There may still be a small amount on the bottom but that will not cause any damage if frozen.

RV antifreeze

You can also winterize with RV antifreeze and fill all the lines with the “pink stuff,” but this will take an additional 6-10 gallons for the water heater. Plus, if you do not have a winterizing valve that can draw the antifreeze through the onboard pump, you need to add antifreeze to the holding tank. That’s a much more difficult process.

Read more from Dave here

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Gary Stone
7 days ago

Most water systems have bypass valves that will prevent pink stuff from filling the water heater tank. So usually only 1-2 gallons of pink stuff will suffice. Antifreeze doesn’t need to go in the water heater if it’s empty.

Alpenliter
7 days ago

And make sure the system is not pressurized when attempting to remove the plug…..

Irv
7 days ago

On my trailer, I can drain more water out of the hot water tank by raising the front of the trailer using the tongue jack than I can by removing the plug. (My hot water tank is behind the wheels and is aluminum so it doesn’t have an anode.)

• Open the low point drains (mine are in the back)
• Open the water faucets to let air into the system

Make sure when you raise the trailer that nothing in the rear of the trailer hits the ground.

Joe
7 days ago

Just to clarify Dave’s comments on heating the threads. Do not heat the plug itself you want to heat the female threaded area (nipple) where the plug screws into without getting heat on the plug. This should help in making the nipple a slight bit bigger, an ice cube on the plug while heating the nipple could help to keep the plug cool and slight bit smaller. during the heating process a light tap on the nipple with a hammer can help break it loose. In similar situations I have put a very very light cote of never seize on the threads before putting on the teflon tape

Thomas D
7 days ago

And if they get the anode out, put some teflon paste on the threads so help prevent that from sticking again

Jesse Crouse
7 days ago

As a plumber I can tell you the operative word here is PATIENCE. Soak with PB Blaster over several days or even a week. Sounds like the drain plug has not been removed for quite some time to be that hard to remove. Good luck with the project.