Air and Dirt Separators in Closed Hydronic Systems

 

 

Hydronic systems, professionally installed and maintained, will operate trouble-free for as long as the equipment in them continues working. One symptom of a system in trouble is the appearance of dirt and particulate. Where are these solids coming from and how do we eliminate them?

 

 

 

 

 

Particulate in a Closed Hydronic System

Have you ever blown down a strainer in a closed hydronic system and found a volume of solids? Have you found pump seals scored or etched? Control valves starting to stick open or closed? There may be particulate in the system. Where is it coming from?

There may be some dirt and debris in the pipe when the system is installed. Larger systems have larger pipe, and that pipe is often laying around the jobsite waiting to be installed. There may be dirt and even biological growth in the pipe. There may be some welding slag or debris falling into the pipe during installation. There may even be some sediment or salts carried in during the fill process. All of this type of particulate should be eliminated during startup.

A properly commissioned hydronic system undergoes a flushing process prior to startup. The fluid is circulated with a proper cleaning solution and then drained and filled with clean water or a glycol solution. Proper chemical inhibitors and balancing agents are added and maintained. This should eliminate the issue before you even start.

Once the initial particulate is removed, the remaining culprit is air. Proper air removal was  dicussed in the last several R. L. Deppmann Monday Morning Minutes. If air is controlled, how does rust or magnetite form? You need air and water to form ferrous deposits.

Besides the proper commisioning of the system and proper chemical balance, proper air separation is the best method to fight particulate in the system.

What Can I Do for Particulate in My Older Hydronic System?

There are systems that are 20 or 30 or 40 years old with particulate causing havoc in the hydronic system. The strainers are not doing the job. At that point, you may want to consider a Bell & Gossett Coalescing Removal Separator for your system.

The B&G CRS is a large bubble in the pipe. It reduces the velocity low enough to allow air to rise to the top to be vented. The heavier dirt is captured and forced to the bottom where it can be blown out of the system.

This product uses a multipass process. It does not remove the air or the dirt in large quantities in a single pass. The system fluid circulates over and over and the air and dirt is removed over time.

Selection and Specification of Coalescing Separators

When you are selecting and specifying this type of product, there are several things to note:

1. These products are selected based on velocity. In general, the standard B&G CRS separators have a pipe velocity limit of around 6 feet per second. This is less than the ASHRAE 90.1 maximum suggestions for variable flow systems over 4400 hours. The CRS-HV, or high velocity model, will have flow rates comparable to or greater than the ASHRAE 90.1 limits.
2. The products are available with or without a removable head. We recommend you specify the removable head. If something large gets caught in the standard model, there is no sure way to get the obstruction cleared without the removable head.
3. There is an option for a neodymium 45H magnet mounted in the bottom of the separator. We recommend this if there is a chance your system will have ECM smart pumps. More on this in a later blog.
4. We recommend you ask for a removable blowdown valve. If the building maintenance is questionable, ask for a motorized blow down valve with automatic features.
5. Of course, you may select this product on the Bell & Gossett esp-Systemwize selection program.