Guidance for air separator selection in hydronic systems 3

[GBAILEY]

I'm looking for help and guidance for selecting air separators for use in hydronic systems both chilled and hot water.

If you take a look at your Bell and Gossett catalog there are several different types if air separators for which to choose. Using B&G nomenclature these include: Rolairtrol, In-line Airtrol, and the IAF In-line Airtrol. Other manufactures have basically the same lines of products as B&G which can be broken down into two categories: the in-line separator and tangential separator.

Given a situation which allows the use either type, why would I choose one over the other? For example, is one type more efficient at separation? Or less expensive? Or easier to install? Or "just plain better"? What are some of the intangables you have found that guide one to select one over the other (which are never listed in product literature)?

Some of the things I have noticed are:
1. The in-lines occupy less space.
2. The tangentials have a greater flow capacity at the same pipe size.
3. The tangentials "seem to me" to be more efficient at separation, although I cannot find proof of that in the literature.
4. I think the tangentials would be more expensive.

Thanks a bunch!

 

[walkes]

We typically use Hamlet & Garneau air purgers in our specifications (inline air separator). They take up much less room and are much less expensive. The thought around our office was that the added efficiency of the tangential type isn't worth the space/expense, given that there are appropriately located air vents throughout the system.

We have installed some high end separators like Spirotherms Air/Dirt separator, the manufacturer indicates that you can then do away with side stream filters (cleans total volume instead of a portion).

The type for installation would depend on your owner's needs, available space, available money etc.

 

[KenRad]

I've always thought of the in-line separators as more geared for smaller, residential systems. I have used only the tangentials for commercial/industrial sized systems.

Supposedly, the vortex effect of the tangentials aids in separation efficiency. And of course whatever device reduces water velocity more will generally be better at allowing the air to settle out. My gut feeling is that the larger tangentials would do a better job. They can also be equipped with strainers, if needed.

---KenRad

 

[AEBuck]

Air removal efficiency for B&G tangential air separators may be determined at

http://fhaspapp.ittind.com/literature/files/8.pdf,

or by using their ESP PLUS selection software. Use this type and locate it in the warmest piping segment of the system if you're serious, because reduction of water velocity is most of the "secret" for this device. The IAS is simply much better than nothing - like the difference between multi 360-degree turn balancing valves and quarter-turn pretenders. In both of these cases, you do get what you pay for.