How to Fix Low Water in Boiler

One common issue with boilers is low water. This can cause the boiler not to work properly and even stop altogether. If you are having this problem, there are a few things you can do to try and fix it.

How to Fix Low Water in Boiler

In this blog post, we will outline some methods on how to fix low water in boiler. Keep in mind that these methods may not work for every situation, so if there is still no improvement after trying all of these methods, it is best to call a professional.

Summary: Having low water in your boiler can cause it to overheat and shut down. To return back to normal levels of pressure, you have to add more water to the system. This can be done by manually refilling the tank or adjusting a mechanical float valve controlling water flow.

When adding water, make sure there’s no air in the tank so you avoid any potential damage to the appliance. Additionally, always use clean drinking water and never add chemicals unless instructed by a qualified technician.

What Causes Low Water in Boiler?

Many factors can contribute to low water in your boiler. Some of the most common include:

  1. If you leak your boiler, it’s possible that water is seeping out and causing the overall level to drop. This is one of the most serious issues and should be addressed immediately.
  2. Another possibility is that the water level sensor or gauge is malfunctioning. This could cause false readings and make it appear as though there’s less water than there is.
  3. In some cases, low water can simply result from evaporation. If your boiler isn’t appropriately sealed, steam can escape and cause the water level to drop.
  4. Finally, it’s also possible that there’s a problem with the fill valve. If this valve is stuck open, water will continue to flow into the boiler even when the tank is full. This can lead to overflow and flooding.

8 Potential Methods on How to Fix Low Water in Boiler

Method 1: Check the Water Level in the Sight Glass

If the water level is low, bring it up to the entire line by adding more water through the fill valve.

If you don’t see any water in the sight glass, or if it’s below the minimum line, shut off the boiler and call a technician. Ensure the boiler is turned off before proceeding.

Method 2: Check for a Leak

Tighten a Valve

If the water level in the sight glass is low, there may be a leak. If you leak, you will need to call a technician, as this is not something you can fix on your own. Otherwise, you may end up damaging your boiler. Sometimes all you need is to tighten a valve or replace a washer.

Method 3: Check the Pressure Relief Valve

If the pressure relief valve is leaking, it needs to be replaced. If you want to do this on your own, First, turn off the power to the boiler. Then, open the valve to release any pressure. Next, disconnect the old valve and connect the new one. Finally, turn the power back on and check for leaks. If there are still leaks, call a technician.

Method 4: Check the Automatic Water Feeder

If your boiler has an automatic water feeder, check to see if it’s set to the correct pressure. The pressure should be between 12 and 15 psi. If it’s not, adjust it accordingly. To fix that, you’ll need to turn off the power to the boiler and bleed the air out of the system. Then, turn the power back on and recheck the pressure. If it’s still not right, repeat the process until it is.

Method 5: Check the Expansion Tank

If the expansion tank is empty, it needs to be refilled. You’ll need to shut off the water to the tank and open the bleeder valve. Once the expansion tank is full, you can turn the water back on.

If the expansion tank is full, but there’s still not enough water in the boiler, there may be a problem with the pressure relief valve. This valve is responsible for letting out water when the pressure gets too high. If it’s not working properly, it could be causing water to be released from the boiler, leading to low water levels.

Method 6: Check the Boiler’s Pump

Turn off the Power

If the boiler’s pump isn’t working properly, it could be causing low water levels. To check the pump, turn off the power and remove the access panel. Then, check to see if the impeller is turning. If it’s not, you’ll need to replace it. Before that, though, you’ll need to bleed the air out of the system. To do that, turn on a faucet in the house and open the bleeder valve on the boiler. Once the water starts flowing from the faucet, close the valve and turn off the faucet. Then, recheck the pump. If it’s still not working, you’ll need to call a technician.

Method 7: Check the Water Supply

If the water pressure is too low, it could cause low water levels in the boiler. First, you need t check the pressure relief valve to ensure it is not stuck open. If it is, you will need to replace it. Next, check the water supply valve to see if it is fully open. If not, turn it clockwise until it is fully open. Finally, check the main water shut-off valve to ensure it is also fully open. If any of these valves are not fully open, it could be causing low water levels in the boiler.

Method 8: Check the Aquastat

Sometimes the problem could be with the water temperature sensor, also called the aquastat. This is a simple fix that involves replacing the sensor.

Turn off the power to the boiler. Remove the wires from the aquastat. Then, use a multimeter to check for continuity between the two terminals. If there is no continuity, then the aquastat needs to be replaced.

Reattach the wires to the new aquastat and turn on the power to the boiler. Check the water level in the boiler and adjust as needed.

If you have checked all of the valves and they are all fully open, but you still have low water levels in the boiler, it is time to check the water supply itself. Make sure that the water supply is turned on and that there is adequate pressure. If there is inadequate pressure, you will need to contact the water company to resolve the issue.

How to Avoid Low Water in the Boiler?

If you want to avoid having low water in your boiler, you should:

Check the Water Level Regularly
  1. Check the water level regularly and top it up when necessary. Because sometimes the water in the boiler can evaporate, so you need to check it frequently.
  2. Check for leaks and repair them immediately. If there are any leaks in the system, it could result in low water levels.
  3. Make sure that the boiler is properly ventilated. If the boiler isn’t properly ventilated, then the water could start to boil and evaporate.
  4. If you have a problem with your boiler, get it fixed as soon as possible. Don’t wait until the water level gets too low before you take action.
  5. Keep an eye on the pressure gauge. If the pressure gets too high, it can cause the water to boil and evaporate.

Following these tips, you can avoid having low water in your boiler and keep running smoothly.

Safety Precautions You Need to Know Before Fixing Low Water in Boiler

  1. Read the manual before doing anything. Sometimes you may miss an important step or detail that could be crucial.
  2. Make sure the power is off before doing anything. You don’t want to electrocute yourself!
  3. Do not try to fix the boiler if you don’t know what you’re doing. Boilers are complex machines and require professional knowledge and skills to fix.
  4. Always bleed the air out of the system before working on it. This will help ensure that you don’t introduce contaminants into the system.
  5. Check all the connections and fittings before starting to work. Make sure everything is tight and secure.
  6. When opening the boiler, be careful of the steam that may come out. It can cause serious burns.
  7. Always use proper tools when working on the boiler. Do not use anything that is not meant for boiler repair or maintenance.
  8. Make sure you know where the shut-off valve is located. In case of an emergency, you will need to be able to turn off the boiler quickly.
  9. Do not overfill the boiler with water. This can cause serious damage and may even lead to an explosion.
  10. Always test the boiler before putting it back into service. This will help avoid any accidents or injuries.

Be sure to follow all the safety precautions when working on or around a boiler. Boilers can be very dangerous if not handled properly.

Check the Connections and Fittings


If your boiler is not producing enough hot water, there are a few methods you can do to try and fix the issue. We’ve outlined some of the most common causes of low water in boilers and what you can do to troubleshoot them. Hopefully, one of these methods will help get your boiler up and running again so you can enjoy hot showers and baths all winter long! Have you tried any of these methods on how to fix low water in boiler? Let us know how it went in the comments.

Leave a Comment