DIY - Drain and Flush Your Water Heater for Better Economy | .....Aaron's EnvironMental Corner.....

DIY – Drain and Flush Your Water Heater for Better Economy

Filed Under: Do It Yourself on December 29, 2009

It’s amazing how many people are unaware of even the most basic home maintenance tasks. Did you know that your water heater, if you have a tank heater (which most do), should be drained and flushed out every year? This is especially true if you have very hard water or if the water from the supply line goes through your water heater before being filtered or softened.

The sediment that invariably builds up in a water heater over time reduces its efficiency, increases the probability of rust or corrosion, and shortens the life of your water heater. Throwing stuff away is bad. Right? Buying a new water heater at $400+ every 5-7 years sucks. Right? Then make it last!

All that’s required for this job is a place to drain the water heater to (in my case, a below-grade sump pump), some pliers to help coax along uncooperative valves, and about fifteen minutes’ worth of your time. Here’s the procedure, with pictures.

Start by cleaning the dust and debris off the top of your water heater. There’s always some, no matter how clean your house is. Your water heater is probably hidden in the corner of a utility closet or down in the basement. Most of us never look at our water heaters so long as they’re functioning. Now check which pipe going into your water heater is hot and which is cold. The pipes are probably covered in insulation (if not, spend the $4 and get some for the hot water line to increase efficiency). I took it off for this photo so you can see what’s going on. The large pipe in the center is the “chimney” from which the exhaust from the burning gas vents. This should be checked for leaks. Use a spray bottle with water and a little bit of dish soap and spray the vent to see if it bubbles up anywhere. If so, duct tape or use heat sink silver tape to close off the leak. That’s CO2 (pure Al Gore) leaking into your house, which isn’t good unless you have a lot of plants. I once knew a guy who vented his water heater and furnace into his greenhouse for added CO2.

The lines going into the water tank should be labeled hot and cold, probably stamped into the top of the water heater. Trace the cold line to it’s nearest shutoff valve. If there isn’t one, turn off the water main coming into your home. Either way, you want the water entering your water heater (cold) to be off. Now at the bottom you’ll find the gas controls. They’re usually a square box with two or three knobs on it.

One of the knobs will say “Off – Pilot – Hot” and another will have temperature ranges. Turn the first knob to “Pilot” and the second knob to its lowest temperature setting. Make note of where the second knob was positioned before–probably on a manufacturer’s mark for the optimum heat setting to save the most energy. You’ve now shut off the heat so the water heater will no longer try to heat water.

In the picture at right you can see the gas box with the Pilot-Hot knob on top and the temperature control knob at front. The large pipe coming into the gas box is the gas line. Directly below the box is a cover (humped). That cover shields the pilot light and gas burners underneath the water heater tank.

If you’re lucky, like us, and you have a separate valve just for the water heater, you can now go run the dishwasher, a load of laundry, or take a short shower to drain most of the water out of the water heater without wasting it. Otherwise, do this in the summer time so you can capture the water in buckets or something to throw on your garden or lawn. Most water heaters hold between 30 and 50 gallons. The label on the unit’s side will say what its capacity is.

Next, attach a garden hose to the drain valve, located somewhere near the bottom of the water heater. It should accept a standard garden hose “female” end. Make sure you aren’t attaching to the pressure relief valve, near the top of the heater, which will only accept the male end of a hose.

Fasten the hose as tightly as you can without damaging anything. This is important because you don’t want it to leak. If you have some, put plumber’s tape around the threads before attaching the hose for extra leak-security. This is important because the water in the heater is likely very hot and you don’t want it spraying all over you.

Once it’s attached, run the other end of the hose to your drain point. Even if the drain is right next to the water heater, you should use a hose. Otherwise, the water will come out in an uncontrolled splash. At the far end of the hose, attach something to act as a filter. In this case, I took a t-shirt, tied off one end, and then slipped it over the hose end and tied it in place with string. Socks, panty hose, or whatever will work. Something you aren’t really worried about getting rust stains on is fine. This t-shirt is destined for the rag bin anyway, so it was perfect.

Now open the drain valve slowly. Remember: lefty-loosey, righty-tighty. Let it drain slowly, opening the valve more and more as you gain confidence it won’t spray from the hose attachment. Open it most of the way unless you have some kind of drain restriction on the other end. I took the cover off of our sump pump hole so I could more easily see what was going on and fit the hose with its custom filter cover in there.

Don’t do like I did and put the hose in right where the float to activate the pump is located, blocking it so that you are threatened with a flood and have to run to move things before your basement becomes a lake. Learn from my mistakes, people.

Let the water heater drain completely. Then go to the shutoff valve you turned the water off from (the water going into the water heater). Turn the water on for about half a minute, then shut it off again. Do this two or three times to “flush” the water heater tank. For those bucketing the water, this will amount to about 9 extra gallons (at most).

Now shut off the drain valve on the water heater (righty-tighty) and remove the hose. Wipe the drain valve off and watch for leaks. Then turn the water on to the water heater again. You might hear it entering the unit, but you probably won’t because of the thick insulation. While that’s happening, go to a sink or bathtub and turn on the hot water faucet. It will likely spit a lot of air before finally producing cold water. Let the air blow out completely before turning it off again. This will help the water heater fill without back-pressure from air in the system.

Now go back to your hose as the water heater refills and remove your filter. Be careful, as it could be full of rust chips and minerals and sediment from the bottom of the water heater. Throw all that in the garbage. If you haven’t drained your water heater in years, you’ll likely have a fair amount of it.

Once the water heater has had at least five or six minutes to refill, turn the gas back on to “hot.” Wait for the ignition, which you’ll hear as a “whoosh” like when you light the barbecue. Let it run for a few seconds, then turn the temperature control knob back to its proper setting. Check everything again for leaks and you’re done!

Now a quick word about that pressure control valve. If your water heater doesn’t have a valve that looks like the one at the right, you should have a professional plumber look at it. If it’s been capped off or plugged with something, you’ll need to have it replaced. Why?

Because that valve is what literally keeps your water heater from turning into a missile should something go wrong and the water overheat and build too much pressure. That’s why. Have you seen Mythbusters? They have an episode where they removed that valve (plugged it), overheated the water tank and BOOM! The water heater launched like a missile through the roof of a house and into the air. That’s not good for your insurance or health, so make sure that relief valve is there and proper.

The gas will have a redundant “fuse” that’s made to burn and cut off the gas flow should something at the control box go wrong. If the gas won’t come back on and you smell a little funky burning metal smell, it means that the fuse was likely tripped for some reason. Get a professional to come in, evaluate it, and replace the box or fuse if necessary.

So there you go! If your water heater is an efficient model (most are now), flushing it occasionally will do wonders for improving its life span and efficiency. There are a handful of models that don’t require yearly maintenance, using some kind of swirling turbo action inside to push the debris out through centrifugal action. I saw one at Sears. It was expensive.

When this water heater finally needs replacement, I’ll probably switch it for an on-demand heater, which uses less energy and has no maintenance at all. We’ll cover how those work in another blog post.