What's New with Manometers?
December 30, 2013
This online-only article is a supplement to the January/February 2014 print edition of Home Energy Magazine.
Imagine leaving your manometer in the basement while you are doing a combustion appliance zone (CAZ) test and then walking around the house, turning on fans, adjusting doors, energizing the air handler, all while you are monitoring the pressure in the CAZ on your iPhone, iPad, or Android device. You wouldn’t have to yell down to your buddy in the basement or run up and down the stairs to check the manometer every time you made a change; you’d see your manometer readings immediately and could more easily create the conditions for the worst-case depressurization.
Or how about this: You’re up in the attic with the blower door running and you want to seal some air leaks and see what the results are for the rest of the house. Turn off the blower door fan, seal the gaps, and turn the fan on again without ever leaving the attic. As the leakage goes down, you can adjust the speed of the fan remotely. You couldn’t do that with a Magnehelic gauge! But you can with the new manometers.
Two-channel digital manometers are fundamental tools in building analysis. Combustion analyzers are the heart of combustion analysis, but when you are trying to figure out what’s going on with the thermal enclosure—specifically, with the air control layer or the pressure boundary—digital manometers are certainly the tool of choice. A manometer can’t tell you if there is insulation in a wall, but it can tell you if there are holes in the pressure boundary. And the manometer has evolved along with the home performance industry. We have gone from using analog Magnehelic gauges to using digital manometers. Now we can use touch screen manometers with communications capabilities.
The Energy Conservatory (TEC) has produced an adapter that is designed to work with existing DG700 and DG500 manometers. Retrotec has produced an entirely new manometer, the DM32. Both manometers offer the wonders of wireless communication but approach it from different directions.
The DM32 is the completely new manometer. It certainly does have a wireless feature, but first and foremost it is a two-channel digital manometer. The early versions had a red and black housing. The latest version has a yellow body with a black faceplate and touch screen.
The DM32 is not much bigger than a fat cell phone. There are no batteries to replace; it is rechargeable either through a USB computer connection or plugged into a wall outlet. The four pressure connections (blue and red for Channel A and yellow and green for Channel b) are recessed into the top edge of the housing to protect them from damage. (One interesting thing about these pressure connections that I’ve always liked is the fact that the inside of the ¼–inch tubing slides over the center fitting of the connector while the outside is compressed by the outside of the fitting. The advantage with this approach is that the inside of the tubing doesn’t get chewed up as it is pushed on and pulled off.) There is also an Ethernet connector on the top edge to connect to the fan for speed control.
On the bottom of the DM32 are a network Ethernet cable connection and a micro-USB connector. The Ethernet connection allows you to network multiple gauges—for multifamily applications, for example. The micro-USB connector is used for charging the batteries, and as an alternative can be your connection to a computer. You can use this connection to update the firmware inside the manometer. As the product went through beta testing, Retrotec adjusted the firmware to ensure sensor accuracy. Incredibly, the sensors only need calibration every five years.
There is a belt clip in the back of the DM32 as well as rare-earth magnets to mount the manometer on a metal surface.
All the controls are touch screen via the face of the unit. Pressing the on-off button for two seconds turns the DM32 on, and the Splash/Logo screen displays momentarily before the device opens up the control screen. The top row of the display shows functional information such as the fan speed percentage, the time average of the readings, whether or not the network connection is alive, and the status of the batteries. The second row is the Channel A reading. The third row is a graphic of the device being controlled and the Channel B reading. The fourth row is the Set Pressure and Set Speed controls. And the fifth row is the Settings button, which provides access to the pressure readings during the Baseline capture process, and displays the baseline for later documentation.
When you press the Settings button, the first screen provides access to the house-under-test area (for Flow/Area, EqLA10/Area, and EfLA4/Area); the house volume (for ACH); and time averaging. The next Settings screen provides access to the wireless network setup, the default @ Pressure entry, a Power Down Time from 15 minutes to 2 hours to completely off, and the ability to turn the key feedback sound on or off. It also provides you with the ability to adjust the slope of the @ Pressure angle. The final Settings screen has Touchscreen recalibration, Firmware identification, and the Language setting.
If you press on the Channel A reading, the Hold function is activated. If you press on the graphic of the fan product being controlled, you are taken to a Range or Configuration screen to select the flow ring. On that screen there is a link to the devices that the DM32 will work with—all the Retrotec devices. With another button press you get to all the TEC devices—from the Duct Blaster to the TrueFlow.
The earlier Retrotec manometer—the DM2—had the ability to control lots of devices and had lots of setup capabilities, but it required some digging for the right buttons to push. The DM32 is more intuitive. There are pictures of devices (although the images take some getting used to). There are pictures of the rings. No more Config button! Since the speed is controlled by the manometer—as it is with the DM2—you can set a percentage of speed instead of rotating the dial, or you can set the pressure you want the fan to achieve. When the DM32 is operating in the Pressure/Flow mode and the fan is running, an @ button appears in the upper-left corner with a red line through it. Pressing this button activates or deactivates the @ pressure feature.
The DM32 can be connected to a computer with a cable or through a wireless network connection. Various pieces of software are supplied with the DM32 that further enhance the features of the manometer. They include Virtual Gauge software, DM32 Configurator software, and Data Logger software.
The DM32 also has an adapter that will couple the manometer to the TEC speed control so that the DM32 can control the operation of all the TEC devices.
This wireless stuff is great, but remember that it is a moving target, particularly in the Android world. My three-year-old phone, for example, is considered ancient. The people at Radio Shack told me so when I went to get a new battery. So when I connected the DM32 to my Android phone, I felt the connection might be unreliable. On the other hand, when I connected the DM32 software (GaugeRemote) to the Apple iPhone, it worked well and reliably. I don’t have an Android tablet, but Joe Medosch (a Retrotec trainer par excellence) says that the software works well with a tablet. But the devices should be the same age in order to provide you with a solid and reliable connection, no matter what equipment you are using.
That being said, I was able to operate the manometer within the limits of the house I was working in effectively and reliably.
The DM32 specifications are summarized in Table 1.
What’s included in the DM32 package:
- DM32 Dual Channel touchscreen gauge
- DM32 USB North American charging module
- DM32 software suite
- Cat5 cable, 7 ft (2 m) blue
- USB cable, 6-ft A to micro B 5 pin gold plated 28/24 awg w/ ferrite
- Antiskid mat
- Laptop-style case
- Tubing accessory kit
- DM32 holder
- Virtual Gauge software
- DM32 Configurator software
- Data logger software
- DM32 USB driver
TEC WiFi Link to a DG700
The TEC WiFi Link works with either the TEC DG-700 or the DG-500 manometer. It creates a wireless network that can be picked up by any computer or mobile device with WiFi capability. The free WiFi Link-compatible software allows monitoring and controlling of the DG-700 gauge from anywhere in the house.
WiFi Link will work with the latest versions of TECTITE and TECLOG programs for PCs and the iTEC-700 utility app for Apple mobile devices. The iTEC-700 app works with the iPhone or iPad to allow you to remotely cruise a TEC blower door or Duct Blaster fan or monitor CAZ pressures while you walk around the house turning exhaust fans on and off. (TEC hopes to have an Android version by early 2014.)
The really good thing about this device is that it works with any DG700 with serial numbers 349 or higher (or any DG500) and has a serial communications port on the top so you don’t have to buy a new manometer. The link is a little 2¾-inch x 1 7/8-inch x 1 5/8-inch black box that connects to the serial communications port. There is a 5-inch-long power jumper cable that plugs into the side of this little box and into the side of the DG700 where the cruise control cable usually resides.
When you plug the power cable into the DG700, the modem in the WiFi Link powers up and the blue light comes on. When you power on the DG700, a green light joins the blue light. When the green light is solid, a WiFi hot spot has been created and is waiting for a connection. When the connection is made either to a computer or to an Apple wireless product, another green light illuminates and a yellow communication light starts to blink as information is transferred.
The iTEC-700 app provides a bright, clear screen on the iPhone with the Channel A information on the top and the Channel B information below it. It has a button to press for the Baseline and another button to press to change the mode. There is a Cruise on-off slide switch, and Time Average, Cruise Target adjustment, and Stop Fan buttons. There is a fan speed slider that you can use to adjust the fan speed from across the house. There is also a display of the manometer model and serial number and the manometer battery voltage. Finally there is a Disconnect button and a little blinking manometer communication indicator that flickers as information is passed between the manometer and the iPhone.
In some ways the iTEC app is easier to use than the DG700 itself. The display is clear, simple, and reliable. I had solid control with it 50 feet away through three walls.
I connected my DG700 wirelessly to my PC and ran TECTITE 4.0 (WiFi). Instead of having to sit right next to the blower door with the cable attached to the manometer, I could sit comfortably across the room and watch the manometer run an automated multipoint blower door test, graph the results, calculate the ventilation requirements for the house based on ASHRAE Standard 62.2-2010 (they’re working on integrating the 2013 version), and create reports that I could give to my customers.
The power consumption may be a problem with the TEC system. Although it doesn’t work out to be all that bad if you estimate about an hour per test (and the average test is probably less than that), that would be about 25 tests per set of six batteries or about $0.35 per test. Just make sure you bring along extra batteries for your tests.
There’s a lot to be said for not having to buy a new manometer and for being able to keep working with the old reliable gauge you have been working with. The WiFi Link is a great addition to a great product. Remote operation is a technique that we can begin to explore now that we have the tools for it.
WiFi Link Specifications
The TEC WiFi Link specifications are summarized in Table 2.
This WiFi stuff is very cool, but as W.C. Fields said, “It’s like tying a hair ribbon on a bolt of lightning!” It’s a moving target. Its reliability and effectiveness depend on the compatibility of multiple devices that are attempting to communicate with one another. For these two excellent companies, entering the world of computer communications will mean they’ll have to respond to lots of questions from their customers that have nothing to do with measuring pressure in houses and everything to do with setting up networks for computers and cellular telephones. Both companies have excellent, detailed support materials and manuals. Oddly enough, in today’s push-button world, these piles of paper are more important than ever, and I would urge people to invest some time reading them.
Retrotec has created a way to remotely upgrade the firmware of the DM32. The DM32 has a solid feel and provides a positive user experience. The product is going to have to prove itself in the harsh environment in the field, but Retrotec has invested a huge amount in creating a state-of-the-art product that is tough.
The reliable DG700 has established itself in training programs and manuals as the primary pressure measurement tool. TEC has made its new communications connection compatible with all of its existing products, including the DG700. TEC’s solution to entering the wireless world may not be the most elegant, but it works.
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