Your Boiler System & Micro-Bubble Air Separators – Why You Should Care!

December 17, 2022

If you heat your home with a central hot water boiler (baseboards, radiant floor, etc.) and you hear funny gurgling or bubbling noises coming from inside the boiler or the piping and heaters, trapped air in the system could be the culprit. This could also be the problem if you notice baseboards in some areas don’t seem to get hot enough. We get calls to check out hot water heat sound issues on a fairly regular basis during the heating season, especially on older systems and those that haven’t been maintained regularly.

While there certainly could be other explanations for those and other sounds coming from a hot heating system, we feel this is a good time to talk about a product that’s built to remove errant air that runns around inside your boiler system, potentially creating noise and trying to make bigger waves for your home comfort. We’re talking about a relatively unknown – but very important – component in your hot water heating system, known as the “air separator.”

In this blog post, we’ll talk a little about these products and focus on high performance micro-bubble air separators that are standard on all new boiler installations that our plumbing and heating team performs. We’ll also do a quick feature on our air separator of choice.

What is an Air Separator?

Burham Series 2 with zones valves AND ARROW

An air separator is a hydronic (water-based) heating system component that automatically removes air from the system. Air develops in the system as a result of the fluid it contains (water or anti-freeze solution) expanding and contracting as it heats up and cools down during normal operation. An air separator, also known as an air eliminator, is the central component in a boiler’s air elimination system. In a worst case scenario, a malfunctioning air separator could literally cause a no-heat situation.

Located in the mechanical room, immediately adjacent to the boiler, the air separator is tied in with the main plumbing connected to the boiler. Their size typically ranges from 1” (smaller homes) to 1½” in diameter, with 1¼” being very common. For comparison, the copper piping delivering hot water to baseboard heaters around the home is often ¾” diameter.

Why is an Air Separator Important?

In homes heated by hot water via baseboards, radiant floor, radiators, and other hot water-powered heaters, a properly functioning air separator helps to keep fluid in the system flowing smoothly and quietly. The air separator is the key component that prevents excessive air from collecting in the system, which could potentially cause an “air lock” preventing heat from being distributed to parts of a heating zone, an entire zone, or in some cases, even the entire home.

Micro-Bubble Air Separators Are Now The Standard

Micro-bubble air separators represent the next generation of air eliminators for hot water home heating systems. They do a far better job than their predecessors, and not all of them are the same.

The Discal 551 Series from Caleffi:
Our Product of Choice

Caleffi logo

Older styles of air separators are essentially a substantial, cast iron plumbing housing, with fairly basic baffles built inside to help remove air from the fluid flowing through the separator. Micro-bubble air separators have a more complex internal design that pulls much more air out of the liquid flowing through it. Our product of choice, the Discal 551 Series Micro-Bubble Air Separators from Caleffi, have an internal mesh element constructed of glass-filled, reinforced nylon. This design makes the separator more resistant to dissolved oxygen and acidic fluids than simple ‘plated’ metals that are used in many products (older design and new).

Discal 551 Series Micro-Bubble Air Separators also feature:

air separator - Caleffi-Discal 551
  • A large, low-flow internal chamber, designed to enhance the interaction between the system water and the air removal mesh, providing optimal air removal and corrosion protection for all piping and components in the heating system
  • Stainless steel internal linkages for maximum durability of moving parts
  • A design which provides a lot of space around the internal components, reducing the likelihood of malfunction or hang-up of float and related mechanisms

These features work together to create a highly effective and reliable air elimination system that helps boilers run quietly and deliver heat more dependably and efficiently, especially as compared with boilers that have older type air separators. Improved long-term protection against corrosion is yet another benefit. Caleffi rates the air efficiency of the 551 Series at “up to 100% removal.” Sounds impressive! One thing we know for sure is that these air eliminators far outperform all options that were readily available not long ago, and that this product stands out from its competitors.

Is a Micro-Bubble Air Separator Right for Your Denver-Boulder Home?

Master Plumber Logo - redWhenever our plumbing and heating team at Save Home Heat installs a new hot water boiler (many that we do are replacements), a new micro-bubble air separator is normally included in the work. It makes all the sense in the world, and it certainly helps to enhance and assure the performance of the system. On occasion, we hear from customers that the baseboard heaters are quieter than ever! Thanks in large part are often due to the new air eliminator.

Air Separator Upgrades for Existing Systems, Too!

air separator - Caleffi-Discal 5517

We also have been known to upgrade the existing air separator on a system whose boiler still has plenty of life left and is operating at a reasonably efficient level. Quieter and more reliable is always better for a heating system, and it doesn’t need to be a brand new piece of equipment in order for a homeowner to benefit from an upgrade.

For more information about micro-bubble air separators, or to schedule a highly informative, low-pressure install quote for your Boulder-Denver area home, please reach out to our team today.

Please contact me to discuss upgrades to my hot water heating system!

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