Learning how to winterize hot water heater on rv setups is one of those chores most of us dread, but skipping it is a recipe for a very expensive spring. If you've ever dealt with a burst pipe or a cracked tank, you know exactly what I'm talking about. Water expands when it freezes, and since your RV's water heater is basically a metal box full of water, it doesn't take much for a cold snap to turn it into a giant, useless paperweight.
The good news is that it's not actually that hard to do. Once you get the hang of it, the whole process takes maybe fifteen or twenty minutes. You don't need a degree in plumbing—just a few basic tools and a bit of patience. Let's walk through how to get this done so you can put your rig to bed for the winter without worrying about any nasty surprises when the thaw hits.
Why You Can't Skip This Step
It's tempting to think that because your RV is parked in a "relatively" warm area or because you've got the heat on, you're safe. Trust me, you aren't. Most water heaters are tucked away in an exterior-facing compartment. That thin piece of metal or plastic isn't going to stop a deep freeze from reaching the tank.
If that water freezes inside, it has nowhere to go but out. It'll split the tank seams or crack the fittings. Replacing a whole water heater unit isn't just expensive—it's a massive pain in the neck to install. It's much better to spend twenty minutes now than hundreds of dollars and a whole weekend later.
Get Your Tools Together
Before you start crawling around, make sure you've got everything you need. There's nothing more annoying than getting half-finished and realizing you don't have the right socket.
You'll generally need: * A socket wrench with an extension. * A 1-1/16 inch socket (this is the standard for most Suburban heaters). * A 7/8 inch socket (often used for Atwood/Dometic heaters). * Some Teflon tape for when you put the plug back in (optional, but a good idea). * A dedicated RV water heater flushing wand (super cheap and worth every penny).
Step 1: Safety First
Before you touch a single valve, turn off the power and the gas. If you have an electric element and you drain the tank while it's still turned on, you will burn that element out in about ten seconds flat. I've seen it happen, and it's a bummer.
If you've been using your hot water recently, let it cool down for a few hours. You're going to be pulling a plug out, and if that water is still at 140 degrees, you're going to have a very bad day. If you're in a rush, you can run the hot water at the sink until it comes out cold to flush the tank with fresh, cool water from your hose.
Step 2: Pressure Relief is Key
Once everything is cool and the power is off, go to the outside of your RV and open the water heater access panel. You'll see a little brass lever near the top—that's your Pressure Relief Valve.
Do not just pull the drain plug yet. If there's pressure in the tank, that plug will shoot out like a cannonball, and a wave of water will drench you. Flip that little brass lever up. You'll probably hear a hiss of air or see a little trickle of water. Leave it open. This lets air into the tank so the water can actually drain out smoothly, kind of like how you poke a second hole in a juice tin.
Step 3: Find and Flip the Bypass Valves
This is the part that trips people up when they're learning how to winterize hot water heater on rv units. You need to find the back of your water heater. This usually involves opening a cabinet, lifting a bed, or unscrewing a panel inside the living area of the RV.
You're looking for a series of valves on the pipes leading into the back of the tank. The goal here is to "bypass" the tank so that when you pump RV antifreeze into your lines later, it doesn't go into the heater. You never want to fill your water heater with pink antifreeze—it's a waste of money (it takes 6 to 10 gallons), and it's really hard to rinse the taste and smell out later.
- Three-valve system: Turn the top and bottom valves (cold in, hot out) so they are perpendicular to the pipe. Turn the middle valve (the bypass) so it's parallel to the pipe.
- One-valve system: Just flip the single lever. It's designed to redirect the flow automatically.
Step 4: Pull the Drain Plug
Now go back outside. Take your socket wrench and unscrew the drain plug at the bottom of the unit.
If you have a Suburban water heater, the plug is usually attached to a long metal rod called an anode rod. This rod is designed to corrode so your tank doesn't. If it looks like a chewed-up piece of gum on a stick, don't worry—that means it's working. If it's almost gone, this is a great time to buy a replacement for the spring.
If you have an Atwood or Dometic heater, you'll likely just have a plastic plug. These can be a bit stubborn, so be careful not to round off the edges of the plastic nut.
Let the water drain completely. Since you opened the pressure relief valve earlier, it should flow out in a steady stream rather than glugging.
Step 5: Flush Out the Gunk
Even if the water looks clear, there is almost certainly a layer of white, chalky sediment (calcium and lime) sitting at the bottom of that tank. If you leave it there, it can harden or get into your lines later.
This is where that flushing wand comes in. Hook it up to your garden hose, stick it into the drain hole, and move it around. You'll be shocked at how much white "sand" comes washing out. Keep doing this until the water coming out of the hole is crystal clear.
Step 6: To Plug or Not to Plug?
There are two schools of thought here. Some people like to put the drain plug back in loosely once the tank is empty. Others prefer to leave it out all winter and just stick the plug in a kitchen drawer so they don't lose it.
If you leave it out, it allows any remaining moisture to evaporate. However, it also leaves a nice little hole for spiders or insects to crawl into. Personally, I like to thread the plug back in just a couple of turns—enough to keep bugs out, but loose enough that any leftover moisture isn't trapped under pressure.
A Quick Word on Antifreeze
Just to reiterate: don't put the pink stuff in the heater. If you've successfully bypassed the tank, you can go ahead and pump your RV antifreeze through the rest of the plumbing system. The bypass valves ensure that the antifreeze flows from the cold line, through the bypass bridge, and straight into the hot water lines without ever entering the tank.
If you're blowing out your lines with compressed air instead of using antifreeze, the process is the same. Just make sure the heater is drained and bypassed before you start pushing air through the system so you don't accidentally blow any leftover sediment into your faucets.
Wrapping Things Up
That's pretty much all there is to it. Once the tank is drained, the sediment is flushed, and the valves are bypassed, your hot water heater is officially winterized. It's a simple routine, but it saves you from a massive headache come April or May.
When spring rolls around, you'll just do the opposite: put the plug back in (with fresh Teflon tape), flip the bypass valves back to their normal positions, and fill the tank before you turn the power back on. For now, you can rest easy knowing your RV is ready to handle the cold. Stay warm!