Engineer's Corner
9:23 am
Wed August 14, 2013

TheEC: Air Conditioning at 102.7FM

Air conditioner
The indoor half of the new split-unit A/C.
Credit Aaron Read

Air conditioning.  Cool heaven for those who have it, blazing hell for those who don't.  It didn't used to be terribly common in broadcast engineering, but it's become moreso in the last ten years.  The reason is that, more and more, audio processors, RDS encoders, audio encoders/decoders, studio/transmitter links, remote control systems, and even the transmitters themselves, have all become increasingly "computer-like" with IC's, hard disk drives, power supplies, electrolytic capacitors and the like.   All things that fail quickly when operated in temperatures above 80 or so, and the warmer it gets, the faster they fail!

In the old days, most of the "analog" gear found in a radio broadcasting plant would certainly last longer in cooler temps, but it didn't really hurt things much so long as the ambient air was below 90 or 100°F.   A simple large vent fan, set up to suck air in through a filter, would usually suffice.  Unfortunately, it would require frequent changing of the filter (the 102.7FM Narragansett facilities' filter needed changing every

Dirty air filter
Ewww...the old air filters got pretty dirty after only 3 weeks!
Credit Aaron Read

two or three weeks in the summer) and no matter how much you filtered, drawing in outside air inevitably mean a lot of dust and dirt got in as well.  Worse, even a high-volume fan, say 1500 CFM (Cubic Feet per Minute) would never cool the room more than 10 degrees above the outside air temp.   A toasty August day of 90 degrees meant a sweltering 100+ degrees inside the facility.  Ugh!  And worse, it might be 100 degrees in the room, but inside the transmitter chassis itself, where all the heat is being generated, it might be 140 or 150°F.  Yikes!

The issue came to a head last winter when we activated our HD Radio transmitter at 102.7 to broadcast on 102.7FM-HD2.  The HD2 "Importer" (as it's called) is literally a WinXP computer in a rackmounted case, running some specialized software.  So we purchased and installed a Daikin 2-ton split-system air conditioner; it just went active last week.  Now it's a cool and comfortable 74°F all the time in there.

Air conditioner
Inside the compressor unit.
Credit Aaron Read

How much is "2 tons"?  It's equal to 24000 BTU, and the smallest window-unit A/C's are usually 5000 BTU.  So it's a fair amount of cooling, but not a "gigantic" amount; just enough to get the job done.  Daikin is a relatively new brand to the USA, but for years they've been popular in Asia, especially Southeast Asia where "heat and humidity" take on a whole new meaning!  And as an added bonus, it's designed to operate even when the outside air is only 50 degrees.  Normal A/C's might start to literally "ice up" when it's that cold out, but it still could be over 80 degrees inside thanks to the heat from the transmitter.  The extra capacity is critical for those spring/fall months when Mother Nature likes to throw us a curveball with the weather.

We've got a simple thermostat wired to the remote control to give us an alarm if the room temp goes above 85°F, indicating an A/C failure.  And the old vent fan is still there; just now it won't turn on unless the room temp goes above 90°F, as an "emergency backup" system.

And of course, your trusty engineer is much happier to do work in the summertime, too!  :)