Planning for Success

If you are waiting for success to just drop in your lap, you may be waiting for a long time. Successful people have to work at being successful. Even after achieving a degree of success, you have to keep working to maintain your current level. However, hard work is not the only pre-requisite to success. Planning makes your efforts more productive by focusing your attention on the details and directing your energy to items which you might otherwise overlook. When teaching HVACR, lab work can be chaotic. Planning helps bring the chaos under control. I will be giving a Webinar on " Tips for Running an Effective Air Conditioning Lab" Wednesday, March 30 at 3:00 PM. The webinar is free. To register, got to the following link

https://attendee.gotowebinar.com/register/8836657677340179713

March Madness is Here!

I am caught up in my own version of March Madness! No, not the basketball championship brackets, but the annual educational seminars and meetings that come every year in the spring. I will be speaking at HVAC Excellence National HVACR Educators and Trainers Conference in Las Vegas on Tuesday, March 22 on “Developing and Evaluating Performance Exams.” If that is not your idea of a good time, then check out some of the other 50 sessions! There will be hundreds of HVACR instructors, and 70 exhibitors showing the latest and greatest at the expo. Youi can find me at the Pearson booth where I will be showing off the brand new third edition of “Fundamentals of HVACR.”  This event is always energizing and inspiring. But wait, there’s more! I will be giving a webinar through Person on “Tips for Running an Effective Air Conditioning Lab” at 3:00 Eastern time on March 30. Please join me to learn how you can plan for success.

Variable Capacity Comfort Systems

Every major manufacturer is now offering some form of capacity modulation on their top line residential HVAC equipment. For several years we have had two stage compressors in air conditioners and heat pumps and two stage gas valves on gas furnaces. Now most manufacturers are offering variable capacity air conditioners, heat pumps, and furnaces. You might wonder why having the ability to produce less heating or cooling is a good thing? Variable capacity equipment is better than fixed capacity equipment for both comfort and energy efficiency,

First, think about the comfort issue. A fixed capacity system is only the right match for your house at one operating condition. Most of the time it is larger than you need. Fixed capacity systems have to shut on and off because they typically produce more capacity than is needed at most operating conditions. This means that they will be over-conditioning, shutting down and waiting for the temperature to fluctuate, and then coming back on. A variable capacity system can operate close to the actual capacity needed to heat or cool your home even at different conditions. This means you will not be over-conditioning, shutting off for a while, and then over-conditioning again. The temperature can remain more constant.

 Energy efficiency is the second big plus you get from a modulating system. The least efficient operation for any system is when it starts. For air conditioners and heat pumps, it takes a few minutes for the refrigerant pressures to stabilize and start producing at rated capacity. However, your system uses the most energy at initial startup. This means that at the very moment the system is using the most energy it is producing the least capacity. Obviously this represents inefficient operation. If a system only runs a few minutes before shutting off, it is always operating at its most inefficient state. Furnaces have similar issues. At startup you are not delivering any heat into the house, but the furnace is using fuel. Again, the most inefficient operating condition. A furnace that cycles on and off every few minutes is operating at its leas efficient condition. Variable capacity systems increase efficiency by reducing these cycling losses. The system operates for longer periods, but uses less energy because it is only using as much energy as is needed for the current condition.

In cooling, longer operation often gives better humidity control in areas where humidity control is as important as temperature control. If an over-sized cooling system cycles rapidly, it does not have time to remove a lot of moisture. The homeowner feels uncomfortable even though the temperature is satisfied. So what do they do? They crank the temperature down until they do feel comfortable. Net result, they over-cool the house to feel comfortable because the system is not removing moisture adequately. Modulating systems can solve this problem by varying both the refrigeration capacity and the airflow capacity – keeping a cold coil even at reduced capacity operation. They operate longer because of the reduced capacity, allowing them to remove more moisture.  Variable capacity systems gaining in popularity because they keep you more comfortable while using less energy.

Affordable Wireless Probes

I just got my first opportunity to play with my new Testo smart probes. The 549i measures pressure and the 515i measures temperature. They are wireless Bluetooth devices which rely on an app that you load on your smart phone or tablet. They are part of a complete lineup of wireless Bluetooth devices that Testo is introducing. I was interested in them because of the low price point. The 549i and 515i are each around $50.  To read both system pressures, the suction line temperature, and the liquid line temperature simultaneously costs around $200.

The App

The Testo Smart Probes app interfaces with all of the smart probes. My first impression is generally positive. Like Testo’s Digital Manifold Gauges, the software does have a small learning curve. However, once you get past the initial setup and learning where all the settings are, you can easily check system pressures, superheat, and subcooling simultaneously. You can choose from a menu of applications which range from a basic list of each probe’s output to a software application designed to make a particular job easier. The software will also do data logging. Each application allows viewing the information as a list, trending (a graph), or a table. With the graph or table view, every time the probe updates its reading, that new reading is plotted on the graph or added to the table. You can export these to pdf, excel or jpg.

Accuracy

The accuracy is reasonable. For improved accuracy, the 115i temperature probe uses an NTC sensor rather than a thermocouple. The specification is plus or minus 1.3° C ( 2.3° F). Its resolution is 0.1, meaning it can display tenths of a degree.  Its range is -40°C to 150°C ( -40°F to 302°F). The 549i pressure probe has an accuracy of plus or minus 0.3 bar (4 psi). The resolution is 0.1, meaning it can display tenths of a pound.  The range is -1 to 60 bar (-14 to 870 psi).

In the Shop

The software and Bluetooth worked well with both my i-phone and my Android tablet. The range seemed fine, I connected to the system and walked around the shop. The app did drop some of the probes occasionally, but they always reappeared in a few seconds. This happened even if I was right next to the probes – so I don’t think it had to do with the Bluetooth range. There is also a latency in the readings of a few seconds. When I disconnected the pressure probes the pressure still showed on the screen for a few seconds.

Batteries

What remains to be seen is how long the batteries last. Each probe uses 3 AAA batteries. It could get a little expensive if I have to replace batteries a bunch. Also, I know neither my phone nor tablet will go all day, so to use these in the field a lot I would need to figure out a convenient way to recharge them.

Wrap up

The exciting part is that these probes bring the wireless world to you at a very affordable price. Just a good quality thermocouple pipe clamp that plugs into your multimeter costs $50. The 115i gives you more functionality and convenience for about the same price. The 549i lets you check system pressures without filling a manifold or hoses up with refrigerant. And both allow you to export the data, so you can provide your company and customers with verification of the system’s performance. Here is  link to a web page about the Testo Smart Probes. https://www.testo.com/en/home/products/smart_probes/smart_probes_heating_1.jsp