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Hot Water Heater Won’t Drain? How to Drain a Clogged Water Heater

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Water heaters are not failproof. Over time, it will have different problems and eventually break down. No matter what type of water heater you have installed at home, they will all have their own issues, despite regular maintenance.

You will encounter leaks at the top or at the bottom of your heater, its inlet and outlet, the T&P valve, and overflow pipe. Loose connections, rust, corrosion, sediment buildup, and unusual noises are also common to water heaters. But, do you know what’s the most annoying issue you can face? It’s having a water heater that won’t drain.

Clogged water heaters won’t be a problem for you if your unit undergoes periodic maintenance. But if you’ve never had your water heater checked out ever since you got it installed, this problem is something that you will face sooner or later.

Unclogging a water heater to drain properly can has varied levels of difficulty. Catch it early and you can get it fixed very quickly. But if you keep putting it off, anyone who will work on it will have a difficult time removing the buildup.

Anyone working on water heaters will also be dealing with hot water, so, safety precautions are a must and this includes wearing safety gear. It is also important that you allow the water stored inside the tank to cool down first before letting a professional check it out. To do this, you should shut off your water heater for an entire day and allow the water remaining inside the tank to remain undisturbed, since draining the water may not be possible.

plumber at work

Why Should You Get a Clogged Water Heater Fixed Sooner Than Later?

You may not experience its effects right now, since hot water seems to be flowing well on your showers and faucets, but it will later manifest. Sediments are the main cause of blockage, and these sediments will damage your water heater the longer it stays there. And because of these sediments, you will eventually have an unusable water heater. It doesn’t matter if you’ve only had your water heater for just a year or so; they will wreak havoc on your water heater.

A clogged water heater is a poorly maintained one that contains a lot of sediments. If you know that your unit is clogged, or at least showing signs of starting to do so, you have to get it fixed by a professional at the soonest possible time. Problems on your water heater will never resolve on their own; left alone, they will get worse.

Water Heater Draining Slowly or Not at All

If you think there is a chance that your water heater is clogged, the technician will do confirmatory tests to see if it is indeed a blockage or your water heater is experiencing other issues. Here are the steps to do that:

  1. Your water heater must first be shut off. Gas water heaters need to have their control knobs set to off, while electric water heaters need to have their circuit breakers switched off.
  1. Before opening the drain valve, a hose must be attached to it first, particularly if the drain is located some distance away from the water heater. If not, he or she may just leave it as is. Afterwards, the technician will open the drain valve.
  1. At the same time, a hot water faucet must be switched on and left open to remove the negative pressure inside the tank.
  1. Water should flow out of the drain at this point. If there is no water coming out, or just trickling out no matter how long you leave the drain valve open, there is likely a clog on your water heater. But if water comes out and is clear, there is no problem with the drain of your water heater.

Causes for a Water Heater Not to Drain

There are two possible reasons why your water heater is not draining. First is a damaged drain valve. If your water heater’s drain valve is no longer in perfect condition, it is likely to prevent water from properly flowing out of its drain. But if the contractor sees that the drain valve is still in great condition, the only reason why water would not drain out of your unit is a blockage on the drain.

If the blockage is the culprit, this would require more time to fix, since a contractor will likely use various methods to resolve the problem. It is not often that this issue is resolved at the first try.

professional adjusting the settings on a water heater

How to Drain a Clogged Water Heater When It Won’t Drain

Now that it is confirmed that your water heater is clogged, the next step is to unclog it. There are so many ways to do so, but any professional will start with the easiest methods first before progressing to the more complicated ones.

To help you understand the process, we have listed down the usual methods of contractors when unblocking a water heater. This is in order of increasing difficulty:

  1. Wait for it. This is obviously the easiest, since the contractor will just sit it out and wait. After following the process of confirming a clogged drain or not, the contractor will close all hot water faucets and leave the drain valve open, with or without a hose attached to it.

This will allow pressure to go straight to your drain, which may force the sediments to flow out on its own. Contractors usually wait for at least an hour before this works. If not, they go to the next method.

  1. Poke it with a wire. If the blockage is not yet that bad, poking around the drain may already dislodge it. To do this, a thin wire, or anything thin and stiff that can enter the water heater’s drain, will be used by the contractor. Before doing so, a bucket or towels may be placed below the water heater drain to catch the sediments and water that will be dislodged.

The contractor will try to loosen up the debris that is stuck by poking it and moving the wire around, repeatedly. If the buildup is not that bad, water will slowly trickle out of the drain. The contractor will repeat the process until the water flowing out of the drain is no longer just a trickle but already a steady flow. Draining the tank afterwards will allow the remaining sediments to flow out.

  1. Get a CO2 drain gun. This gun can be used by your contractor to clear out the drain using compressed air. Before using the drain gun on the valve, he or she will first open the pressure valve of your unit. The drain gun will be used to shoot up compressed air to the drain valve, and the force may be enough to remove the clog.
  1. Stomp on the connected hose. The next method your contractor will usually do is to reconnect the hose to the drain, then step on a section of the hose that is around two feet away from the water heater. Doing this will create an air bubble on the hose, which will flow back to the drain to hopefully dislodge the blockage. The contractor will usually do this repeatedly to loosen up the sediments, because they have the tendency to go back and re-clog your drain in the process.
  1. Back-flush or reverse flow. This method involves using a washing machine hose. The contractor will connect one end of this hose to the water heater drain and the other end to a garden hose, which is connected to a faucet or any other water source. This water source will be turned on for a few seconds for water to flow into your unit via its drain, instead of water coming out from your unit via the drain. The flow of water coming may be strong enough to force the sediment buildup to loosen up and unclog your drain.

To see if this worked, the contractor will shut down the water source and remove the connected hose. Then, he or she will drain the tank and see if water will now flow out of the drain.

  1. Remove the drain valve and replace with a new one, preferably brass. If the sediment buildup is just too severe, the next recourse for a contractor is to just remove the entire drain valve, even if it is still in good working condition, and replace with a new one. Any skilled professional can do this even without having to drain the water heater, especially in situations like this. Speed is important when doing so.

A contractor will first wrap the new drain valve’s threads with Teflon tape and close all open hot water faucets. Basins or towels will be placed under the drain to catch water which will flow out when the drain valve is removed.

The old drain valve is then removed from your water heater, preferably using an adjustable wrench, and the new one will be installed. After installing, the contractor will now drain your water heater’s tank.

  1. Use a ball valve as a replacement for your unit’s drain valve. If you use hardwater for your water heater, sediments will likely go back and settle on your water heater, especially if you still don’t have your unit regularly maintained. One way of preventing your water heater from becoming clogged again is to replace your drain valve with a ball valve, which is larger in size and will hinder clogging.

For a water heater, the ideal replacement is a ball valve measuring ¾” and two dielectric nipples of the same size. The threads of the ends of the nipples that would be connected to the ball valve must be wrapped in Teflon tape. Only one of the unconnected ends of the nipples must be wrapped in Teflon tape, as well. Towels or buckets should also be placed below the drain to catch water that will flow out once the drain valve has been removed.

The technician will shut off all available faucets before removing the drain valve from your unit. After this, the ball valve will be immediately installed in place. He or she will then drain your unit and when this is done, the handle on the ball valve will be removed to prevent it from accidentally being turned to drain hot water.

  1. Change its position and location. Are you planning to replace your main water heater, but still want to use the clogged one somewhere else? This is possible by moving your current unit outside and unclogging it there. Instead of forcing the sediment buildup to go out from the drain, the technician will reposition it so that it is lying on its side. At this position, water will be drained out from the top of your water heater and not from the clogged section.

Water heaters are generally heavy, so your technician will usually make use of various equipment for him or her to be able to transfer your unit, especially if it is installed or located in your basement. Also, it is vital that the water inside the tank be cooled down first in order to avoid possible injuries to whoever is working on your unit.

As a non-professional, the only method on the list that you can possibly do on your own is the first one, which is to wait it out. After all, you’re really not going to do any kind of work on your unit.

If it is still not clear to you, what we mean is that this problem is best left only to professionals. Working on water heaters is not as easy as changing the pipes of your kitchen sink; they have complicated systems that will easily malfunction if they are improperly handled. And more often than not, these malfunctions will cause a lot of problems for you, even forcing you to replace your now unrepairable unit with a new one.

How to Replace Your Water Heater Drain Valve Without Draining

If you’ve read a lot of guides, including ours, about installing and repairing different components of your water heater, you might have noticed one of the most common steps mentioned in all those articles. It is about how professionals drain water from the tanks before doing the actual work on any unit. Draining is important, as this will prevent any accidents that may occur if anyone comes into contact with hot water.

But what do you do if draining is not possible? How are you going to get your water heater serviced by the plumber? Does this mean you already need to get a new unit, after all?

Fortunately for you, skilled professionals are capable of working on water heater units even without having to drain it beforehand. This is very handy, especially if you are faced with a clogged drain valve that needs to be replaced. There is no way to drain water first in cases like these, after all.

Is it really possible? This guide will show you how the experts typically do it:

  1. Cut off both the power and water supply of the water heater. In particular, a gas water heater must have its control valve set to pilot and an electric water heater must be powered off.
  1. Completely rid the tank of hot water by opening all of the hot water faucets available and leaving them alone until cold water starts flowing from them. This will prevent hot water from flowing out of the drain hole while work is being done on the water heater, as this can cause accidents.

It is important that only hot water faucets will be opened, since this will also produce much-needed air vacuums. This often takes quite some time, with some reportedly spending as much as an entire day waiting for the water to cool down.

  1. Before removing the current drain valve, the new one to be installed needs to have its threads wrapped with Teflon tape first.
  1. Place a bucket below the drain valve, as this will catch the water and sediments that flow out once the technician removes the currently installed drain valve. This drain valve needs to be opened first for around three seconds to lessen the pressure inside.
  1. Loosen up the current drain valve using tools such as a pipe wrench, slip joint pliers, or adjustable wrench. Water will start leaking as soon as the technician starts unscrewing it from the water heater. He or she will continue doing this until it has completely detached.
  1. The contractor will do some maintenance work and remove the sediment buildup that has caused the blockage of the water heater. He or she will use one or two of the methods we previously mentioned and will also likely do a complete draining of the unit to remove the sediments stuck in the tank.
  1. The water that flows out of the drain hole must be clear and free of sediments, before the new one will be screwed into place, with it pointing downwards when done.
  1. After it has been screwed into place, the technician will check if it is a tight fit and if leaks are present. If so, he or she will have to re-screw the drain valve until the leak disappears.
  1. All open faucets must now be switched off and the drain valve will be tested if it was installed correctly.
  1. If there are no issues after the installation, power and water will be supplied back to the unit and its tank will be refilled with water. Your drain valve should now work properly.

Changing a drain valve is a fairly straightforward process, even if the water inside may not be drained beforehand. And if it needs to be changed, it is highly recommended that your old drain valve be replaced with a ¾-inch brass drain valve, which is the standard size and what we recommended earlier. Plastic ones may be much easier to install, but they are very prone to leaking, causing you to have them replaced sooner and more often.

Like what we emphasized in unclogging a water heater that won’t drain, it is equally important to get a qualified professional to replace your water heater’s drain valve for you, especially in scenarios like this. It is already quite hard to replace it even with the water drained, it is even more complicated to do so with an undrained water heater.

How Do You Prevent a Water Heater from Clogging?

After all the trouble you’ve gone through to have your water fixed, it is important that you take measures to prevent it from happening again. You may have hired a professional to fix it for you this time, but who’s to say that it can be resolved again the next time? There will definitely be a next time, if you still overlook caring your unit.

First of all, you need to look into using a water conditioner, if you haven’t yet. Sediments are very common to hardwater, and if your unit has this issue, you are likely dealing with hardwater. Water softeners help remove the minerals that cause blockages in a water heater. Those that aren’t dissolved by the water softener will remain inside the tank.

This is why regular maintenance on your water heater is important, especially doing routine flushing or draining. By doing so, you prevent various minerals and sediments from settling on your water heater, causing blockage, and flush them away before they have a chance to solidify. These are the primary culprits for a clogged water heater.

Having a professional do a periodic checkup and maintenance on your water heater is not just about preventing clogs from happening. It’s also about preventing disastrous consequences that may occur to you and your home, as a result of a neglected unit. We’re talking about bad leaks that can result to flooded basements and water heaters that can turn into ticking time bombs and explode, among others. These may sound farfetched to you, but trust us. It happens.

water heater being repaired

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