Tag: testo

Photo by Brad Hicks at HVAC in SC

Right off the top let me state loud and clear. The tool does not make the tech.

Let that sink in before you move on.

A good tech has a solid understanding of WHY they are doing what they are doing, the basic math of the trade and enough experience to spot most problems with their senses before they reach for a tool at all.

However… there are some cases when you need a specialty tool. You need it so much that you cannot do your job without a good one (Leak detectors and micron gauges come to mind). In some rare cases, the cheap version of a tool and the high-end version are so different that you are at a real disadvantage if you don’t have the quality version.

There are multiple manufacturers who have come out with wireless pressure probe technology. Up until recently, I couldn’t get over the fact that you cannot use these probes for charging and recovery… why would you want a separate tool set in addition to your gauge manifold?

Well… I think I finally get it. Here are some reasons that others have given me that have me seeing the light.

Low Loss

One big advantage is you can use the probes to check a system charge with no hose losses. This is huge for systems with a critical charge (Think Ice Machines), when doing regular preventative maintenance and when hooking up to the system to check it during a service call unrelated to charge. Keeping all that charge in the system is a service to the customer and helps save expensive refrigerant. You can keep some 90 degree core depressing adaptors or some short hoses to help connect in tight spots .

Additional Readings

With smart probes you can now check additional temp and pressure readings without the need to move your hoses around when you do have a manifold attached. You can check liquid and discharge pressure simultaneously, check temp drop across a liquid line or superheat gains across the suction. All great data that the wireless smart probes can help with.

Hard to Get Readings

Now this one was the one that tipped the scales for me and it was brought to my attention by tech Joe Shearer (Thanks Joe). You can use the smart temp sensors (Testo 115i) to get readings on running systems in spots where wired probes can be almost impossible. Reading superheat inside a heat pump condensing unit during heat mode, reading temp differential across a reversing valve and taking discharge temp at the compressor are all examples where the smart temperature probes come in really handy.

The MeasureQuick App

Testo is one of the first tools that works along with the new MeasureQuick app for full system diagnosis unlike anything you have seen. This may feel like a pitch, but working with MeasureQuick as well as the great price make the Testo Smart Probes a very attractive option.

So I think you may want to think about smart probes and if they might help you….. Once you already are confident enough to understand why and how you would use them to be a better tech.

— Bryan

P.S. – If you are interested you may consider going HERE and looking at the Testo smart probes. If you do buy from TruTech tools use the offer code “getschooled” for 8% off your order.

 

 

Testo 557 vacuum gauge and Appion core removal tools shown

I’ve had a change of heart.

Back in the early 2000’s during the big construction boom I did a lot of system startups on residential units for a large company I worked for.

When installers were running the linesets prior to startup they weren’t always very careful to keep them clean and dry and many times we would end up with a restriction in the piston or TXV.

These new residential systems come with a precharged with refrigerant in the condenser. So after my vacuum was complete I would “release” the charge by slowly opening the liquid line service and watching to see if my suction pressure would steadily rise.

I did this so if there was anything in the liquid line it would hit the screen or drier before the metering device instead of possibly running the other way and clogging the TXV or orifice.

Many times I would know that there was a restriction before I even started the system because I got used to watching that suction needle rise. While I did this for a good reason that reason is in the past.

When we install systems we take great care to make sure the lineset stays clean and dry and we flow nitrogen while brazing with the line drier installed near the indoor coil.

It’s a new day and I’m giving up my old sins.


So now I must admit… the better way to do it is to slowly open the SUCTION valve first. This prevents oil loss out of the compressor into the discharge line and out of the liquid line.

It is not likely that you will lose enough compressor oil to cause any damage by opening the liquid line slowly, but any oil the compressor does lose has a long journey before it gets back to the compressor. The other issue is that oil loss in those first few moments in the life of a new system can have long lasting effects on the operation and longevity of that compressor.

Have you ever taken a liquid line hose off after a new system install and gotten oil all over?

The reason for that is often due to opening the liquid line first and the compressor losing oil to the discharge line and then to the liquid line.

When you open the suction side slowly first and oil loss from the compressor will enter the suction line. Once the compressor begins running no it will pull that oil back into the compressor.


When doing it this way you would attach your micron gauge to the liquid line core remover side port with the schrader in place in the side port. Once you completed your vacuum and proved you had no leaks or moisture by valving  off the VCT’s and watching your decay rate. You would then attach your gauge manifold and slowly crack the suction side until you see a few psi on the liquid side. Now remove the vacuum gauge to ensure it is not damaged by the system pressure.

Most micron gauges can handle some pressure, for example the Testo 552 can handle up to 72 PSIG(4.96 bar) and many can handle 400 psi(27.57 bar) or more. it never hurts to remove that expensive and sensitive micron gauge before you expose the sensor to high pressure, but never remove it BEFORE the system is under positive pressure or you will lose the entire vacuum.

You would then purge your manifold hoses and fully open the suction valve and then the liquid line valve.

When charging a system that has no charge (not running) weigh refrigerant into the liquid line first until both sides equalize in pressure to ensure that you are not introducing liquid refrigerant right into the compressor crankcase.

Also keep in mind that running the crankcase heater once the charge has been released and before the system is started is also a good practice to prevent flooded start on the compressor.

— Bryan

In this video we cover the basics of using the Testo 510i with a pitot tube to do a duct traverse and easily calculate Velocity in FPM and volume in CFM on a small 8″ duct. Using this method is handy because you can use the reliable, accurate and inexpensive 510i to perform the measurement without any other equipment other than tubes and a pitot tube.

As stated in the video, a pitot tube is best (most accurately) used in the following conditions –

  • Medium to High Air Velocities
  • With 4 -8 feet of hose
  • In low turbulence air at least 8.5 diameters downstream of any turns, fittings or diffusers (I was less than this in the video resulting in lower accuracy)
  • In a duct at least 30 times larger than the pitot tube diameter (It was less than this in the video resulting in lower accuracy)

 

For more information see the following links –

Dwyer Guidelines

TruTech Tools Traverse Quick Chart

TruTech Measuring with a pitot tube

Testo 510i specs

Video on the performance of a rectangular time average traverse

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