How to blow out the boiler

Every homeowner’s first concern is making sure their house stays warm and comfortable throughout the winter. Maintaining the best possible condition for your boiler is a crucial part of this. Blowing out the boiler, or clearing out built-up sediment and debris, is an important part of boiler maintenance. We’ll walk you through the process of properly blowing out your boiler in this post, ensuring that it runs safely and effectively.

It’s critical to comprehend the necessity of blowing out your boiler before beginning the process. Minerals and silt may gather at the boiler tank’s bottom over time. If this buildup is not removed, it can cause corrosion and other damage in addition to decreasing the efficiency of your boiler. Frequent boiler blowouts help to avoid2 / 2

Purpose of boiler blowdown

Make-up water typically has impurities in it that build up in the drum boiler and cause the water’s salinity to rise.

This means that these materials must be eliminated from the water cycle system. Blowdown is a continuous removal process used in drum boilers.

To avoid sludge, oxidized iron, and mechanical debris entering the heating plant’s screens and collecting in the collectors, these materials must be removed through this process. Water must adhere to the standards outlined in the equipment documentation and water-chemical regime instructions.

Depending on the water’s color, the boiler house staff may flush the operating equipment up to twice a day per the chemical control specialist’s instructions.

Steam boiler blowdown

Salts are deposited on the heating surface of the steam equipment during the evaporation of water, and when the surface continues to heat, the salts solidify into sludge in the boiler’s lower sections. This results in inefficient heat transfer, higher fuel consumption, and ultimately pipe, drum, and drum damage.

As a result, it’s critical to guarantee that the machinery runs without limescale and that the furnace is promptly vented. In order to keep steam units operating in the proper manner, cleaning—that is, removing foreign particles along with water—is done. There are two types of blowing, which will be covered in more detail below. Periodic blowing is done on a regular basis to clear sludge from the boiler’s lower boiler part’s screens, drum, and collectors.

Although this process is quick, a lot of water is used in it. A cooling expander receives the water discharged before it reaches the sewer system. Steam boilers that are flushed frequently eliminate contaminants from the boiler’s upper section. Steam and water are separated as water enters the separator.


Water-water heat exchangers are used to connect hot-water boilers to the heating system in order to improve operational stability.

High-quality make-up water is required in the boiler; to achieve this, the closed circuit is periodically and continuously blown. The iron compounds are removed by this process.

Our goal in writing the article "How to Bleed Your Boiler" on our "Heating and Insulation of the House" website is to help homeowners understand this easy yet important procedure. Your heating system may experience damage and inefficiencies if air becomes trapped inside. By allowing trapped air to be released, bleeding your boiler ensures effective heat distribution and guards against future issues. We’ll go over detailed instructions for safely and successfully bleeding your boiler as well as advice on how to troubleshoot common problems. By following our simple instructions, you’ll be able to keep your house warm and comfortable during the winter, preserving energy and extending the life of your system.

Types of blowdown

Periodic and continuous flushing are the two types of flushing that were previously discussed. The first is meant to remove impurities from sludge, and the second is meant to guarantee that the boiler water has the required minimum amount of salt in it. The service technician determines how often periodic blowdowns occur and how many blowdowns occur continuously.

Periodic purging

When the water level in the drum is higher than usual, two workers perform this type of work. Here, one person flushes the toilet directly while the other keeps an eye on the water level.

The process of periodic flushing involves multiple steps:

  1. Verify the serviceability of the line.The section of pipe between the boiler and the flushing valve should be hot, and behind the valve – cold.
  2. Check that the shut-off valves and gauges are working properly.
  3. Smoothly opens the second valve.
  4. After that, carefully open the first valve from the boiler to avoid water hammer.
  5. The opening time period of the first valve should not be longer than 30 sec. Then the second valve after it is closed.

Verifying that every valve is closed and the line is airtight after the process is finished is essential. The shift logbook shows the procedure’s beginning and ending times. Water containing impurities is drained from the boiler’s lower section during routine flushing. Furthermore, flushing contributes to lowering the boiler water’s salt content. A line pressure meter assesses the procedure’s quality.

Continuous blowing out of the boiler

A permanently open valve from the boiler’s top that is situated on the flushing line allows for continuous blowdown. A pipe with holes around the drum allows water to flow evenly.

This is required to remove the water that contains salt and replace it with an equal volume of cleaner make-up water. The flushing volume is typically up to 3% of water. This is enough to keep the water’s salinity at the necessary level.

The percentage of water diversion is established based on the amount of salts in the water, which is determined by a chemical analysis specialist. Steam enters the deaerator, water from the boiler enters the separator, where it is separated from water, and tainted water exits the cooling expander and enters the sewer system.

Step Description
1 Turn off the power to the boiler.
2 Let the boiler cool down completely.
3 Locate the pressure relief valve and open it to release any built-up pressure.
4 Attach a hose to the drain valve and place the other end in a bucket or drain.
5 Open the drain valve to allow water to drain from the boiler.
6 Once all the water has drained, close the drain valve.
7 Close the pressure relief valve.
8 If needed, use compressed air to blow out any remaining water from the boiler.
9 Inspect the boiler for any signs of damage or leaks.
10 If everything looks good, close all valves and turn the power back on.

It’s crucial to maintain your boiler properly if you want to keep your home toasty and comfortable throughout the winter. Blowing out the boiler, or clearing out any sediment or debris that may have accumulated inside, is an essential part of boiler maintenance. This procedure makes sure your boiler keeps working properly by extending its lifespan and increasing its efficiency.

Following a few steps can help you complete the relatively easy task of blowing out the boiler. The boiler must first have its power turned off and given time to cool fully. You can find the drain valve and connect a hose to it once it has cooled. After that, turn on the valve to let the water and silt out. Make sure you are prepared with a bucket or other container to catch the water.

It’s crucial to monitor the water exiting the boiler during the draining procedure. Excessive sedimentation or discoloration could be a sign of a buildup that requires attention. Until the water runs clear, you can keep draining as often as necessary.

After emptying the boiler, shut off the drain valve and take the hose out. After that, you can switch the power back on and add more fresh water to the boiler. Additionally, it is a good idea to look for any leaks or strange noises that might point to a boiler issue.

Your heating system will function effectively and dependably when you need it most if you schedule routine boiler maintenance into your daily schedule. Although blowing out the boiler is only one part of this maintenance, it can have a big impact on how well your boiler works and how long it lasts.

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Sergey Ivanov

I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

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