October 2012
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Control Solutions, Inc. - Minnesota

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New Trends and Products in HVAC Control

Unheard of just a few short years ago

Steven R Calabrese

Steven R. Calabrese
Control Engineering Corp.

Contributing Editor 



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Funny how when you look back a decade or two, you question as to how you ever got along without this, or without that. This applies to everyday life, as the advances in technology spur new ways of doing things. Things that maybe we’ve done all along, but now are done with relative ease given the new technology. Or things that we do now that we’ve never done before, because the technology affords us so. The same thing applies to how we do things in our industry, specifically as it applies to controls, but generally as well to how it applies to mechanical systems and so on.

Often a new trend takes hold that predicates the need for a new product or new way of doing things. This is so true with the controls business, as when you think about current trends (energy conservation, IAQ, LEED, etc.), you tend to notice the new products being offered that tailor to these trends.

In other cases it’s simply the technology allowing us to do something easier than we’ve been able to do it in the past, or being able to do something that we’ve never been able to do. Till now.

In this month’s column, I’ll take a look at some “relatively” current trends, and some of the products that have been borne of these trends. I’ll also take a look at some products that are simply offered up as an easier way of doing things, products whose “time has come”, so to speak.

Combination Sensors

Ever seen more than one sensor enclosure mounted side-by-side in a single location? Ever wondered why they couldn’t figure out how to put both sensors in a single decorative enclosure? Well, wonder no more, for now is the era of combination sensors!

Combination space temperature / humidity sensors are really nothing new. These items simply combine the two sensing devices into a single enclosure, bringing the leads of the sensors to a common terminal strip within the enclosure.

The Indoor Air Quality (IAQ) trend has spurred the need to measure and monitor CO2 levels in occupied spaces, primarily to ensure the proper amount of ventilation air per occupant, at any given level of occupancy. CO2 is an indicator of human life, and so you get the idea. The space CO2 sensor has been around, its cost coming down and reliability going up in recent years. Yet should you need to monitor space temperature and/or humidity, along with space CO2 level, you’re back to mounting more than one sensor side-by-side. Not any more! Enter the multi-function space sensor. Yes, three sensors under one hood (I sound like an ad man)! Seriously speaking, this is good news from an aesthetics standpoint, not to mention installation and serviceability. Makes good sense, and certainly an idea whose time has finally come.

Self-contained BTU Meters

BTU meters have been around for awhile now. Developed to fill the need for monitoring energy consumption in hot and chilled water systems, their popularity has been heightened by the LEED movement, as well as driven by the need to conserve on energy and improve operational efficiencies. These meters are typically made up of a system of parts, including a flow meter, a pair of temperature sensors, and a brainbox. The flow meter gets installed in the (hot or chilled water) supply pipe. The temperature sensors get installed in the supply and return pipes. And the brainbox gets mounted typically on a nearby wall, with the flow meter and temperature sensors wiring back to it.

Enter the “self-contained” BTU meter. A pre-assembled system of parts, the flow meter and supply water temperature sensor are pre-mounted onto a common “spool-piece”. The brains are also a part of this assembly, the only thing “loose” being the return water temperature sensor. Makes installation a bit easier, and simpler to understand the concept. Wiring is limited to the return sensor and the brainbox output, which is either a control signal to indicate BTU consumption, or a communication interface (such as BACnet). In fact, the return sensor may already be wired as part of the assembly, though the cabling included may need to be “cut down” a bit, or even extended, if need be. Just be careful and heed the manufacturer’s installation guidelines before severing a pre-wired cable (words to live by!).

Solid State Damper Position Indicators

When I was a kid, I played around a lot with electronics kits. The kits I speak of are those of which a bunch of solid state electronic components were embedded upon a cardboard layout, and you would connect components together with wires, to create circuits from the book supplied with the kit. Memorable circuits include the crystal radio, the lie detector, and the household plant “water me” circuit.

Another circuit that remains in my memory is the light activated tone generator. Utilizing a light sensitive photoresistor, you would wave your hand over the component, and the tone heard through the little speaker would fluctuate as a function of the level of light hitting the photoresistor. I’ve pondered time and again in my professional career how this technology could be applied to, say, a damper position indicating device. For years we’ve had the old encapsulated mercury switch that mounts on the shaft of a damper and can give two-state indication of damper status (open/closed). What about true position indication? Couldn’t a photoresistor be used in a device that could give you a proportional control signal indicative of damper position?

Reliable Controls Ponder no more, because it has arrived! A solid state damper position indicator that gives true position indication. The technology used isn’t quite what I’d envisioned, however the result is the same. I imagine that it’s akin, technology-wise, to what’s used in a smart phone, when you tilt it from vertical to horizontal. Anyway, you mount the device on the shaft of the damper, calibrate it in some way, and its output is a control signal that’s proportional to the position of the damper, from fully closed to fully open. Neat stuff. And can I say, it’s about time!
 
Condensation Indicators

Back to those electronic kits and some of the circuits that I built…two that I mentioned earlier, the lie detector and the “water me” circuit, relied on the fact that water is a conductor of electricity. Both of these circuits consisted of probes that, if joined together with some level of moisture to complete the circuit, an audible alarm would sound. For the lie detector, the “defendant” would hold a probe in either hand, and be asked questions. If the defendant began to sweat, the moisture would help his/her body conduct a small amount of electricity, albeit enough to be amplified and sound the alarm. For the “water me” circuit, same principle but in reverse; if the plant needed to be watered, the probes inserted in the soil would cease to conduct electricity, and a logic reversal circuit would sound the alarm.

Fast forward in life a few years, and a friend of mine really into cars had a moisture sensor fastened to his windshield, such that if it started to rain, the sensor would automatically close his sun roof if it were open.

Getting back to the point of this column, we now see this technology running rampant in the controls industry. My specific example is with the strap-on pipe condensation indicator. Good to know if your pipes are sweating (for whatever cause), especially above a lay-in ceiling! This device straps to the pipe, and offers a contact closure to tell you (i.e. your Building Automation System) that you have a problem, hopefully before you start ruining ceiling tiles.

Tip of the Month: Not so much a tip this time around, than a plea…send me your ideas for other new trends and/or products, such that I may write a second installment on this topic. I have a couple more ideas under my belt, but would love to hear from you and write about your ideas!


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