Saturday, May 2, 2015

Mission HVAC


Shuretape has launched an initiative to follow three students at Athens Technical College through their studies in the Air Conditioning Technology Program. To support the students, Shurtape is challenging them each to a series of missions. They complete the mission and report their findings on the Shurtape blog. They have chosen three students with different backgrounds and different ages: Matt Morris, Daniel Buth, and Josue Treo. By following these three students’ blog postings, you can gain some perspective on what it is like to be an HVAC student preparing to enter this profession. They receive a new mission every month. The best way to find out more about these three outstanding students and their mission is look at the Shurtape blog http://www.shurtape.com/blog

Friday, April 24, 2015

Keeping Your Cool!

Hot weather is coming, and that can mean slow refrigerant recovery. It is common to have high recovery tank temperatures and pressures shut you down as the temperature rises. The condensing temperature of the refrigerant in the recovery unit has to be higher than the outside temperature, and so the refrigerant leaving the recovery unit can be hot, especially on a hot day. This raises the recovery cylinder temperature and pressure, which in turn makes the pressure leaving the recovery unit climb even higher since it must be higher than the cylinder pressure. You often need to cool the recovery cylinder to keep going. There is the old stand-by: ice and a bucket. It works great, but involves the extra bother of carrying ice and a large bucket to the job site. You can use the recovery machine to cool off the cylinder.

Connect the vapor valve of the cylinder to the inlet of the recovery unit and the liquid valve of the recovery cylinder to the outlet of the recovery cylinder. Purge both hoses of air. Start the recovery unit with both cylinder valves open. After the unit gets started, turn the liquid valve on the recovery cylinder clockwise to create a restriction. Be careful NOT to completely close it off. You have just made a refrigeration system with the refrigerant recovery cylinder acting like a flooded evaporator.

The recovery unit is provides the compressor and condenser, and the partially closed liquid valve on the cylinder acts like a metering device. Liquid in the cylinder boils as vapor leaves, cooling off the remaining liquid. The returning liquid is at a lower pressure and temperature, thanks to heat being removed by the recovery unit and the pressure drop at the liquid valve. It takes a bit of practice to learn where to set the liquid valve, but you can monitor the two pressures on the gauges of the recovery unit. You should see both pressures drop as the unit operates.

I have made cylinders frost on the bottom using this technique. One caveat – if you wait until the high pressure switch on the recovery unit opens, you can’t use this method to cool the cylinder down since the recovery unit won't run at that point. You need to make sure and cool the cylinder before that happens. One manufacturer used to make a recovery unit with this feature built in. You connected two lines from the recovery unit to the cylinder, and anytime you needed to cool the cylinder down you would just set the recovery unit valves to subcool. This kept you from having to move your hose connections after the cylinder was cooled down. However, I don’t think it is available any more.



Saturday, April 18, 2015

Tape is Tape NOT!

I must admit that when Glenn Walter of Shurtape offered to do a presentation on duct tape application for my class I thought “Oh HOW exciting!” (Yawn) After all, how much can there be to know about duct tape? It can’t even connect to the internet! But then I really hate to turn away help and I like having people from the industry come talk to my students, so we set up a class. One thing I have come to understand about life in general: whenever I think there is nothing to know about a particular subject, it is only because I know so little I don’t understand how ignorant I truly am. When Glen started his presentation I quickly realized that there is whole lot to know about duct tape. What follows is a cliff notes version.

Duct tape consists of a backing and an adhesive joined together. There are four types of backing: cloth (the old standard), film, foil, and foil-skrim-kraft (FSK).  There are two large categories of adhesives: acrylic and rubber based. Most techs know that codes require UL 181 tape. However, did you know that there are two general categories of UL 181 tape: 181-AP and 181-FX.  AP is rated for use on rigid ductboard and FX is rated for use with flex. Note that there is no specific UL rating for tape on metal duct systems – UL 181 is for ducts made out of manufactured materials. You may have also seen tape with a UL 723 rating, which is a smoke and flame spread standard. It makes a difference WHICH UL rating your tape has. Just because you see UL does NOT necessarily mean your tape is correct for the job. Even two tapes with the same UL rating can have different application specifics. Also note that the UL rating is not based on the backing or adhesive, but the tape performance in specific tests. Shurtape has 181-FX tapes with foil, film, and cloth backing with both acrylic and rubber adhesive. They are all approved for use with flex duct, but each has a specific application where it is better. For example Shurtape’s film backed tape with acrylic adhesive is rated for application between -20°F and 220°F. Their other FX rated tapes won’t stick at -20°F.

Most codes now require mastic for sealing metal ducts, but many people still use tape underneath the mastic. Did you know that many duct tapes are not rated for that use? Mastic does not stick well to film tapes. Not all cloth tapes play well with mastic because the chemicals in the mastic and the chemicals in the tape adhesive may not be compatible. The cloth tape might turn loose, then having the tape underneath the mastic just creates a place where mastic is not fully adhered to the duct. Foil tape usually does fine under mastic.  You should check with the tape manufacturer before using a tape underneath mastic.

Finally, the tape application is not complete until you apply pressure. For foil backed tapes, a plastic tool with a stiff rounded edge is preferable for working the tape into the duct. The pressure is needed to fully activate the adhesive on the tape. The adhesive undergoes a chemical process, similar to glue setting. Duct tape is not fully adhered until this process has been started through pressure application and completed with time. Believe me, there is a LOT to know about duct tape. If you would like to learn more, contact Glenn Walter of Shurtape at gwalter@shurtape.com

Saturday, April 11, 2015

Bluetooth Tools for HVAC

At the recent HVAC Excellence Instructor’s Conference there were many digital tools featuring Bluetooth connectivity on display. These tools allow you to use phone and tablet apps which take readings from the device as input. This can be as simple as just displaying a reading, or more helpful such as using the reading to perform a calculation. Most also allow the user to use their phone or tablet to send the information to someone else. Technicians can send real time readings to a service manager for consultations or document results to verify system operation. Most of the devices were measuring pressure and temperature. Of course, the Stride i-manifold was there. It was actually introduced last year. This year they have company. Fieldpiece has had wireless gauges longer than anyone else, but they used a proprietary signal. This year Fieldpiece was showing a set of digital gauges with Bluetooth and a Bluetooth wireless bridge to allow their older Fieldpiece wireless gauges to connect to Bluetooth.

 Yellow Jacket, Appion, and Sporlan all had pressure and temperature measurement tools which featured Bluetooth connectivity and apps designed to work with the tools. To be sure these are not manifolds, but pressure and temperature measurement tools. Appion had a trio of pressure gauges and a Vacuum gauge. Their gauges each have a digital display as well as sending Bluetooth information to your phone. They are “short” gauges with a short stem, allowing connection without filling a set of hoses with refrigerant. The Yellow Jacket Mantooth device is also a “short” gauge, but it has no display. Like the i-manifold, it relies on your phone or tablet for a display. The Mantooth consists of a digital pressure gauge with a tethered temperature clamp. Sporlan was showing off a set of digital pressure and temperature devices with Bluetooth connectivity. They also rely on the connected device for a display. 

All Bluetooth devices were not gauges - Fluke and UEI were showing Bluetooth enabled digital multi-meters and clamp amp meters. 

All these devices were showing apps designed to work with the device and extend its usefulness. Most can be freely downloaded. The i-manifold app is a killer app that is useful even if you don’t have an i-manifold. The Stride folks are hoping you will get tired of typing in the pressures and temperatures and pick up an i-manifold. One final consideration – If your gauges, multi-meter, thermometers, and vacuum gauge are all connecting to your phone while you work, you are going to need some extra juice to keep operating. You will need an extra battery pack or two for your phone, most phones won’t operate all day long without a recharge.  

Saturday, March 28, 2015

WiFi Thermostats

Almost 40% of ALL thermostats sold in 2014 which were WiFi capable. To me, that is an astounding figure. Around 10 million thermostats were sold and just shy of 4 million of those were WiFi capable. Of those, almost 800,000 were sold through HVAC dealers and the rest through DIY outlets such as Lowes or Home Depot. My numbers came from a session Tim Burke of Emerson presented at the recent Instructor’ Conference in Orlando. No matter your view of the utility or necessity of having thermostats connected to WiFi, CUSTOMERS have clearly spoken. The manufacturers are starting to listen and WiFi offerings abound. Just because a thermostat is WiFi capable does not mean it is necessarily a smart thermostat. The WiFi options might simply be to view and set your thermostat from your phone. There are WiFi thermostats selling at under $100. At any rate, our techs need to be up to speed with these devices. An HVAC Service Tech working on a system with a WiFi thermostat should be able to get the thermostat connected to the customer’s WiFi router. I can envision service calls that involve issues with WiFi connectivity, such as “My phone cannot find my thermostat,” or “I changed my router and now my thermostat won’t connect to it. Smart thermostats which “learn” your habits and program themselves can cause issues if the homeowner is not happy with what the thermostat has decided to do. Knowing how to make these behave can be valuable. I know a couple of contractors who have removed these for customers and replaced them with digital non-programmable thermostats at the customer’s request (and expense).

Many digital thermostats will run completely on batteries, allowing you time to play with the thermostat while reading the instructions.With all digital thermostats, I recommend to students that they install the batteries and make sure they can set up the thermostat before installing it.  If the thermostat is already on the customer’s system it can be a bit tougher. One thing to do is make yourself familiar with the most common types sold in big box stores in your area, such as the NEST or the LYRIC. You should also familiarize yourself with the apps these things use so you can show customers how to use them. If you want to offer an alternative to the big box stores, look for full featured thermostats at your local wholesaler, such as the Emerson Sensi or a WiFi Honeywell Focus Pro. Do you HAVE to do all this? No, you can let someone else make all the money that comes from servicing the large number of customers who want WiFi thermostats. Did I mention these also tend to be the customers with the most money?

Sunday, March 8, 2015

Meet Me in Orlando!

I will be speaking in Orlando at the HVACR Educators & Trainers Conference. I will speak on Sunday, March 15 at 8:30 on “Using Social Media to Extend Your Reach.” I will speak again on Tuesday, March 17 at 8:30 on the same subject. Social media and the inter-connectivity of individuals through the internet has brought about many changes in the way people communicate and information is spread. Although the iPhone did not invent “smart phones” or social media, the explosion of internet connected devices and the effect on Social Media can be clearly seen. In just a few years smart phones went from a curiosity carried by executives and geeks, to something everybody felt they needed. The first generation iPhones were sold in June, 2007. In less than 8 years these types of devices have become so ubiquitous that it is truly unusual to meet someone who does not have one. Note that several large tool and equipment manufacturers now make devices which are specifically designed to take advantage of this technology. For example, the imanifold digital gauge set which has no screen, but uses your tablet or smart phone. Now Yellow Jacket is selling its Mantooth device- again a refrigeration gauge which depends on your phone for a display. Flit just released an infra-red thermal imaging camera that clips onto your i-phone. An infrared thermal imaging camera that fits in your pocket and costs under $1000! There are bore scopes that use the phone as the screen as well. Just the fact that these companies have invested their research time and money into these projects shows how commonplace hand held computers have become. Our challenge is to figure out how to use these ubiquitous personal communication devices and the net to advance education.

Sunday, March 1, 2015

The Internet of Things

I read two statements in Kyle Gargaro’s HVACR News editorial that really jumped out at me. He said that 40% of the thermostats sold in 2014 had internet capability. Later he stated that in the coming years the number of devices connected to the internet would exceed the number of people. I found that a little unnerving. Then I thought, I am not connected to the internet, my computer is – and it is definitely a thing. So what is so weird about my thermostat being connected to the internet? Digital thermostats are really just small computers with a very specific task. The difference is just in the human interface and the much narrower scope of operation. However, the real idea of the internet of things is not so much to allow us to talk to our thermostat. There is not really a lot to say to your thermostat. It is the possibility of our things communicating with each other so they can accomplish their tasks cooperatively. For example, the alarm clock can tell the thermostat, coffee pot, hot water heater, and toaster when I plan to arise. They can all use that information to make sure they each perform their function in a timely manner, so I have warm water, a warm house, hot coffee, and toast all at the right time. Or an internet connected electric meter can tell the thermostat when electric rates will increase and decrease, allowing the thermostat to consider the ideal time to turn back my system. I heard a great use the other day on NPR. A cardiologist has his patients wear a bracelet that monitors their blood pressure. The wrist device is connected to their phones via Bluetooth and they can upload their blood pressure history to his office. He can see not just the blood pressure when they walk in, but what it has been for a week or a month. The connected things allow the doctor a much better view of their health, so he can make more informed decisions. Suppose you had all the system’s relevant voltages, pressures, and temperatures before you got in your truck? Or a tool that takes those readings, provides a diagnosis, and offers possible corrective actions? These actually exist now, but they are the exception rather than the rule. I think they may become commonplace when the internet of things takes off.