Air Separator in Chilled Water Systems?

[lgchouston]

Do we need an air separator in chilled water systems?

I know that it is a must for hot water systems... but I am not sure if we need in the chilled water systems?

Is this topic discussed in any engineering guidelines, codes, requirements, ashrae?

 

[AbbyNormal]

You have to be able to get the air out of the system.

For starters try chapter 12 of the 2004 ASHRAE handbook on HVAC Systems and Equipment.

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[lgchouston]

Thanks for the info. I looked at chapter 12 of the ASHRAE book.
It mentions: "Air and other gases must be eliminated from the flow circuit", and I understand that.
But what I've heard is that in chilled water systems there aren't generation/creation of air bubles or gases, this only occurs in the hot water systems (boiler).

 

[lilliput1]

At least you must have an air purger. A company makes them up to 24". You have to get the air out or the piping will be noisy.

 

[SAK9]

Air seperator for chilled water systems is not a must.An air purging during commissioning will be sufficient.

 

[KiwiMace]

Put an Automatic Air Valve at the high point of the system, this will look after most applications.

I'm currently looking at putting a 24" air-dirt separator in a system that doesn't have a lot of vertical rise. These units are about 13ft tall!

 

[AbbyNormal]

Never had the best of luck relying on maid-o-mists myself

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[willard3]

If you never take feedwater after initial system purge, you won't need an air separator in a chilled water system.

Your system will, at some point, take feedwater......separators are inexpensive.

 

[HeshamM]

Air separators are mandatory in large chilled water systems. Even in smaller systems, when all the air is purged out during initial filling, the amount of air which can be dissoloved in the water differs according to the pressures i.e. at certain pressures the water can't dissolve the air. The air then forms pockets and affect the system pumping as well as the heat transfer. Continious automatic air venting must be maintained.

 

[Golestan]

Even Chill water system will need a mean of relieving air. Air is contained in the solution and will come out. Specially if you have throttling valves or components of hight pressure drop. At least you should have automatic air separators on high points of the Hydronic system (multiple points).

 

[daly1]

you might want to consider a smaller run around air separator. I've had similar concerns on a couple large chiller plants and we installed say a 6-8" air sep along with automatic air release valves at every change in elevation.

 

[RossABQ]

Some form of air removal needs to be provided, but it doesn't need to be an air separator. If possible we put a Tee in the highest line, branch vertical, a foot of pipe and a welded cap with a manual vent valve there. The first month or so of operation, the valve needs to be checked for air. After that "maybe" annually if you have a good, tight system.

"Vortex action" separators have a definite pressure drop, 5 ft or so as I recall, and paying for that day-in, day-out is a waste. They are not cheap, and require significant structural reinforcement to hang them.

Automatic valves have a habit of leaking.