Hot Water Heater Expansion Tank Problems: Reasons And Solutions

There is an expansion tank water heater in every household with a radiator and warm water facility. So, it makes sense to familiarize yourself with all the hot water heater expansion tank problems.

Because sooner or later, you will face these issues and you should know what happens when an expansion tank fails and what to do about it, right?

Luckily, you are on the right spot to identify such problems and take corrective measures before something big happens!

Common Expansion Tank Water Heater Problems

hot water heater expansion tank problems

First, have a  look at those common expansion tank heater problems:

  • Excess Water Issue
  • Water Leakage Issue
  • Condensation Problems
  • Valve Problems
  • Air Blockage Issue
  • Less Air In Diaphragm Tank/Steel Tank

When the hot water heater expansion tank stops working properly or your tankless water heater goes cold suddenly, it can lead to a serious problem. For example, it may cost a lot to replace it when it’s too late. It can even explode!

I don’t mean to scare you but you can avoid all the bad things if you can identify the problems before it’s too late. Here are some common problems you can face:

  • Excess Water

The physical volume of water increases when it’s heated. The expansion tank provides the necessary space for the bigger water to flow.

When the gages or valves are damaged, they can’t regulate the flow of the water inside the tank. So, it may lead to excessive water build-up in the tank which eventually may explode.

Apart from the explosion, it may ruin the floor near the heater, hit electrical circuits, spill out water onto the floor, and other problems.

  • Condensation Problems

Before I explain how it happens, let’s see what damages can happen due to condensation problems. Water may drip down onto the electrical components which can be seriously dangerous.

If it drips down onto the floor, things can get seriously messy. It will lead to mold and mildew production too. Condensation can damage the tank itself as well by causing it to rust outside.

Let’s see why it happens in the first place…

There will be excess condensation on the tank outside when it’s holding too much water or the heater temperature setting is too high.

If your tank is over-insulated, there will be condensation during the humid climate.

If the size of the tank is too small, the frequent usages will lead to condensation as you will be refilling with cold water more frequently.

  • Water Leakage

The tank may leak water due to wear and tear (more discussed later in this article). Many parts of the tank may wear out over a period of time.

If the water is leaking from the pipe located at the top of the tank, you can use a wrench yourself to tighten the fittings. But don’t overtighten it!

However, you should not try to fix the problem if the leak is coming from the expansion tank itself. It’s a much bigger problem and requires the touch of a professional plumber.

  • Valve Problems

Is the expansion tank pressure too low? If so, you should pay attention here. There are many valves inside and outside the tank in every water heater system.

And when the valves don’t work properly, they may damage the entire system and you will have less water pressure.

There are so many reasons why the valves and related tubes may rust, strip, or even break.

Besides, mineral deposits can collect inside the tanks and clog the system if you have hard or soft water problems. When the hoses and tubes are clogged, you will have less water pressure.

All those incidents will lead to damaged valves and tubes. You should replace them with completely new valves and tubes. Only the new parts like these can hold up better against such rusting and corrosion.

  • Air Blockage

The internal mechanism of your expansion tank for hot water heater is designed in such a way so that the air can sit in the hot water system. The whole system needs air to function properly.

But when the air gets trapped and causes a hydronic airlock. As a result, the air can’t pass through the heater and the pipes.

So, if there is no hot water in the radiator, it means you have an air blockage problem that needs to be fixed. When the expansion tank works properly, there should not be such blocks.

The right thing to do in such a case is to call a plumber to determine whether you have a problem in the expansion tank or not.

  • Less Air In Diaphragm Tank

If your expansion tank is not too old, it probably uses a diaphragm system to keep the air and water apart. But the tanks can lose air through the valve in a small amount.

You need to add more air to the tank in such a case so that it can work properly. You can use any air compressor to add air attaching it to the valve attachment.

If adding air does not fix the problem or the tank is still filled with excess water, you should replace the diaphragm. Call a plumber to determine whether the diaphragm needs replacement or not.

  • Less Air In Steel Tank

If you have an old expansion tank that does not have a diaphragm to separate the air and water, it may absorb a smaller amount of air. So, your tank will lose pressure and won’t work properly.

You could refill the tank with air yourself closing the isolation tank and draining water from the tank, but I would recommend hiring a plumber to do this for you.

Also Read: What to do if the faucet hot water is not working?

Expansion Tank For Hot Water Heater: How It Works?

measuring air pressure of expansion tank

The main task of the expansion tank is to regulate the water and air pressure in the system. It gets problematic when there is excess pressure in the hot water supply of your home.

Your water heater and water lines will be severely damaged including all the fittings without it. It’s the expansion tank that prevents all the issues related to that excess pressure.

Usually, a rubber valve separates the tank into two sections. The bottom section contains pressurized air to match your home’s water pressure and the top section allows the water to flow through.

It’s the single vital element that protects the entire plumbing system of your home. Not just your property, it protects you and your family members too!

Depending on the quality, the tank can serve you for 5 to 10 years. So yes, it wears out naturally.

But it will be damaged fast if the water pressure of your house does not match the tank’s air pressure.

You can run a thorough check by a professional plumber to check the status. When damaged, you may need to replace the expansion tank water heater.

Frequently Asked Questions (FAQs)

What happens if expansion tank fails?

It will cause the pressure relief valve of the boiler to vent water. It may also lead to air blockage that will stop the flow of hot water.

Should an expansion tank be full of water?

No. The expansion tank should be filled with water and air.

How do you know if your expansion tank is bad?

You should check the pre-charge pressure of the tank to determine whether it has gone bad or not.

Use your knuckles to knock on the side of the tank to check whether it’s full of water or air. If the pre-charge pressure is too low, it’s full of water.

What happens if expansion tank pressure is too high?

If there is a partial blockage in the tank due to black sediment, your expansion tank may have hot water in it.

How do you fix a waterlogged expansion tank?

The problem is your tank has already lost the air charge necessary to function properly. Add air to solve the problem.

Final Thoughts

So, you now know all the hot water heater expansion tank problems and the probable reasons behind them. To detect such problems earlier, you should always hire a plumber to perform regular inspection and maintenance.

It’s your only safe bet! And no matter what you do, do not try to fix those problems yourself unless you have done this before. Pay the plumber!

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