Friday, March 4, 2016

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.

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.

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.

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