View Full Version : Active Chilled Beam Systems
01-01-2011, 07:00 PM
I just did a search for previous threads related to this, but the posts I found were very old. Looking for some current input.
My primary contract is a campus of Gov buildings in which the next new building is going to incorporate the "Active Chilled Beam" technology. I am curious as to the performance of these systems in my climate---Wash DC.
I install and service controls, and wonder what to expect in those regards as well. The moderator may wish to move this thread, but I'm just looking for general opinions of the technology-------nothing to deep.
01-01-2011, 07:29 PM
The chilled beams perform sensible cooling only. There will be a dedicated outside air system (DOAS) that brings in outside air that does the latent work.
Chilled water supplied to the chilled beams will be at 55*F. I know of one job that has what is being called the high temperature chiller for 55*F water. It has to be that warm so that there is no moisture removal, or else there will be condensation on the chilled beam coil with no place to go but down on the occupied spaces below. The chilled beams do not have a condensate pans or removal abilities.
I hope this helps you.
01-01-2011, 07:34 PM
control of the doas is important, as well as having logic to control the high tewmp chilled water slightly above dewpoint to prevent condensation, specfiically after a long power failure in summer. they work just fine soo far.
01-01-2011, 07:35 PM
The chilled beams perform sensible cooling only. These systems will have a dedicated outside air system (DOAS) that brings in the outside air and performs the latent heat removal.
The chilled beams will be supplied with 55*F chilled water, it has to be that warm so that there is no moisture removal, because the chilled beams do not have condensate pans or removal abilities. If moisture was removed by the chilled beams, it has no place to go but to the occupied spaces below.
I know of a building that has what is being called a high temperature chiller, because it is supplying 55*F chilled water.
I hope this helps you.
01-02-2011, 11:30 AM
Thanks for your input. I can't wait to see them in action--------if we land the bid.
01-02-2011, 01:40 PM
it isnt really all that magical. the biggest concern, to me, is the doas desgin and performance. I can tell you one mistake I have seen that isnt pretty......designing a doas with wheels specified for counterflow, and then chaniging the layout to parallel flow without reselecting the wheels. performance suffers. also, design of the mixing station if using a single chiller and two temp distribution is important.
01-02-2011, 07:27 PM
If you guys on the east coast can make them work, I'm impressed.
How often do you make indoor rain?
01-02-2011, 07:31 PM
They work just fine, if you do a lot of air changes, and do proper control of the doas and secondary chilled wawa. I have seen one case of a long power failure, and the techie from big red had to sit there and sloooowly bring the building back to prevent rain in the building on a noce hot summer day.
01-02-2011, 09:41 PM
We were looking at such a system for a new building that ended up being postponed.
The ventilation design engineer got real nervous when I asked him how much extra dehumidification he had to build into the supply air handler. This was one of those "energy driven" designs, and he looked at me real funny and said "we can't call it that".
Also, part of the "energy savings" idea was to cut way back on the air changes and supply fan capacity. Might have gotten away with it out here, I don't know.
We'll eventually get to building one if I survive this economy that long. Ten to twelve years to go, here.
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