July 2013 |
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New Trends and Products in HVAC Control (Part Two) Continuation from fall 2012 column |
Steven
R. Calabrese |
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Last year in the October installment of this column, I presented
several current trends that are impacting our industry, and the
products that go along with some of these trends. At the end of the
column, I asked for your ideas for other new trends and products to
write about. Well, I received quite a few emails, and so I thank you
for your support, and present to you this month a few of those that I
thought were worthy of discussion, as well as being uncomplicated
enough for me to understand and describe. So here they are!
Wireless Switch Transmitters / Control Relays
Ever hear of the Enocean Alliance? From their website, they are a
“consortium of companies working to further develop and promote
self-powered wireless monitoring and control systems for sustainable
buildings…” So they play a big part in the development of wireless
devices as the one that is the topic of this discussion.
The wireless switch transmitter is, from its appearance, a wall mounted
switch that looks like a light switch. Which is what it is. Except that
it can do more than turn a light on and off, and it does what it does
using no wires and no battery! The switch generates a small amount of
electricity when pressed, enough to send a signal to a nearby control
relay (nearby meaning within 100 feet or so, and that would be pushing
the limits). The relay requires power, however you’re switching
120-volt power with it anyway in a typical lighting application, so you
just need to bring the neutral to it as well as the hot.
The switch has several selectable modes of operation, including
momentary mode and rocker mode. In momentary mode, the switch acts as a
momentary pushbutton; the relay activates when pressed and deactivates
when released. Could have some good applications. However the rocker
mode is the most common. Throwing the switch one way activates the
relay, and throwing the switch the other way deactivates the relay.
Just like a normal light switch.
As stated above, the wireless switch transmitter / control relay has
its applications in lighting, however a little “thinking outside the
box” and you can find dozens of uses for this bad boy in HVAC controls.
What comes to mind for me are all of those simple little situations in
which you need to get “from here to there” but hardwiring would be
prohibitive or extremely costly. Not to give any specific applications
here, for I’ll leave that up to you!
Internet Thermostats
Way back in 2009 (a long time ago in terms of technology) I attended
the AHR Expo, held in Chicago that year. I ended up doing a product
review on something that was a relatively new concept at the time. The
device is a residential grade thermostat that connects to the Internet
using a WiFi chip that ties into your home’s wireless network. The stat
has a touchscreen and is fully programmable, can access the weather,
and has Demand Response capabilities built right into it.
Demand what??? Demand Response is a process by which a facility will
automatically shed its electrical load in response to a signal from the
Internet. Without getting too into it, suffice it to say that there are
signals available via the Internet that have to do with peak events and
electricity price changes. Well, this thermostat can act upon such
signals, to avoid peaks and shed electrical usage when prices are high.
Pretty neat stuff.
The thermostat is accessible via your smart phone, for remote
programming and remote control of different parameters, remote
monitoring of temperatures and other variables, remote notification of
various alarm conditions, and remote troubleshooting. A long time
coming, but apparently we’re finally there! To control your heating and
cooling equipment, in a mobile manner, from anywhere in the world, is
pretty remarkable. But I guess we kind of expect to be able to do that by
now, huh?
Wireless Pneumatic Thermostats
I read about these recently, and had one of those “it’s about time”
moments. The typical application is the pneumatically controlled VAV
system that you would find in an older commercial office building. The
terminal units (VAVs and FPBs) have pneumatic damper actuators,
controlled by pneumatic thermostats in the spaces served. Short of
committing to a complete DDC retrofit of the terminal units, what could
be done to upgrade these units to a more current mode of operation and
control? Well, here’s your answer! Installation is simple. Replace the
existing pneumatic thermostat with a new, battery-powered wireless
thermostat. The new thermostat controls the terminal unit much like the
old one did, however the wireless feature allows BACnet communication
with a central transceiver that connects to a Building Automation
System (BAS). So you get BAS control of space temperature setpoints,
including time-of-day scheduling and unoccupied mode override
capabilities. And you get space temperature monitoring, which you can
use in DDC strategies such as air handler discharge air temperature
setpoint reset. Trending, alarming, troubleshooting…all the things that
go with DDC control. So in short, the terminal units stay pneumatic,
yet at the same time become “one with the BAS”!
Economizer Module
For rooftop unit OEM and retrofit applications, several manufacturers
have for years offered “economizer control modules”. These modules are
either factory-installed in a typical rooftop unit, or are put in
“aftermarket” as a replacement or as an upgrade. They consist primarily
of a “main brain” module that controls the economizer (outside and
return air) dampers of the rooftop unit, to provide free cooling when
outdoor air conditions permit. Also wired into the main brain are
outside air temperature and humidity sensors, or more commonly an
outside air enthalpy controller. The enthalpy controller senses both
temperature and humidity, and typically has a setting on it that you
adjust depending on the climate. The setting is/was somewhat
rudimentary, meaning that there are no actual values on it that
correspond to the OA temperature + humidity, only letters that indicate
how “aggressive” you can be in setting the enthalpy “setpoint”, that
point at which you would allow/disallow economizer operation.
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Now comes a new twist on the trusty ole economizer module. Yep, another
“it’s about time” moment for me! A major manufacturer has just released
a new product that allows you to input the ZIP code in which the
economizer is to be installed. So no more guesswork and no more
fiddling with the changeover control. Just pop in the code, and you’re
good to go for the climate in which you’re in. More to it, of course,
but still an idea whose time has come.
Energy Dashboards
The term “dashboard” has been around since we’ve been able to drive,
however recently it has taken on a new meaning in our industry. So what
is an energy dashboard? In simple terms, it’s an interactive energy
measurement and management tool. Typically rooted in a facility’s
Building Automation System (BAS), it utilizes data gathered from
sensors and electrical meters, and presents information in an
easy-to-understand format that caters to “the common folk”. Which isn’t
to say that you can’t “drill down” to find more detailed information.
But the primary focus of a dashboard, just like the one you have in
your car, is to give you basic information from which you can act upon
and make better decisions on how to operate your vehicle, or in the
case of the energy dashboard, how to operate your facility. In a
nutshell, the energy dashboard is a tool that can be used as a means of
tracking energy consumption, in order to reach energy efficiency-based
goals. In other words, to reduce energy usage and save money!
So where does it exist? Well, given that a particular energy dashboard
is derived from a facility’s BAS, then it exists within the BAS, or
more specifically, typically in a web server. So accessible via the
Internet, just as the BAS is. The difference is that, the energy
dashboard won’t allow for any modifications through its means of
interface, which could be a personal computer hooked up to the
Internet, or perhaps a smart phone with web access. Or you may be familiar
with the kiosk style display or interactive touchscreen that we see
more and more of in the lobbies of commercial facilities and
multi-tenant office buildings. In whatever form it takes, the premise
is the same: make this information available and visible to the average
Joe, give them some means to interact with it, and encourage the notion
of using it to benchmark energy usage and to promote efficiency within
the facility. What a great concept! I’m actually thinking of setting
one up in my own home!
Tip of the Month: Remember that first topic? Challenge yourself to come
up with five applications in which you could utilize a wireless switch
transmitter and control relay. Jot them down and save the list for
future reference. Betchya it won’t take long to put one of those
applications to practical use!
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