Updating Your SMAN/Testo Gauges
October 17, 2024
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Some of you might have an older SMAN/Testo digital gauge. With the new refrigerants coming, you might need to update
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Technical Services Manager
North Georgia District
In this newsletter we will cover a few key topics that will explain a few details pertaining to the use of R 454b. We will continue to cover more details in future newsletters. This briefing will give a few important and updated details to prepare you for the change in refrigerants.
Safety is of main concern with the A2L refrigerants. A few things are still up in the air, under research and could change as new information becomes available. We now know that Carrier/Bryant equipment up to 25 tons will have R 454b. This includes ductless and VRF at the current printing of this newsletter.
Charging/servicing techniques will remain the same when switching from Puron to Puron Advance as they are both low glide blends. Charge limits are based on the home’s square footage and other design criteria. The equipment should be properly leak checked and should be evacuated and purged before any brazing.
The refrigerant 454b system’s cylinders color will be a light green gray. The A2L refrigerant cylinders will have a red top for identification, to warn that it contains a mildly flammable substance. The cylinders for A2L refrigerant drums will have left-handed threads.
The cylinders for the A2L refrigerants will feature a pressure relief valve instead of a rupture disc, for increased safety. A relief valve will only release content until the pressure setting allows the valve to close. Also, the technician will not lose the entire drum of refrigerant should it be released. The technician can continue to use the remaining refrigerant until the drum is emptied. The disposal procedures have changed also. For A2L cylinders, a non-sparking piercing tool, like a brass punch, must be use to puncture the side of the cylinder before disposal.
The recover cylinder is gray in color with a yellow top. A2L cylinder will have a red band as well as left-handed threads. And as always, keep a refrigerant type clearly identified and do not mix refrigerants.
Most A2L refrigerants are so mildly flammable that there must be a direct flame source and a high concentration of refrigerant to create a flame. If and A2L refrigerant were to ignite, the flame would be unsustainable. An A2L refrigerant flame would spread at an extremely slow speed, less than half a mile per hour. You can walk faster than that. Most A2L refrigerants are difficult to ignite, because they have a high MIE or minimum ignition energy. Many common household items like a cordless drill, toaster, hair dryer, or electric heater will not ignite A2Ls. They require higher concentration levels to achieve a flammable mixture.
So what type of tools will be needed to work with Puron Advance? We now know for sure you will need a left-handed thread adaptor for your refrigerant drum. Some tool manufactures are now selling left-handed hoses charging hoses that will help with this issue. Well, it requires the use of hand tools and equipment with no spark and no ark. Make sure all the tools that you are purchasing are UL certified. Your current gauges, digital or analog and hoses used with 454b can be the same as used today, however, a dedicated set should be used the same as when working on R454b and 410a to avoid cross contamination. Check with the manufacturer to make sure equipment is rated for use with R 454b. 454b cylinders will have a red top and the hose connection will be reverse threaded or left-handed threads. As always, before beginning work, make sure equipment is properly grounded.
Now we’ll talk about some primary concerns with equipment containing slightly flammable refrigerants. One of the primary concerns is refrigerants ignition of a refrigerant leak during equipment operation, the potential for refrigerant ignition during equipment service, and a refrigerant release during a structural fire. As always as mentioned above, a few things are still up in the air and could change as information becomes available. One thing is for sure, you will need to have a fire extinguisher always rated Class B for a chemical fire available.
The primary areas of concern of oxygen displacement are the release during transit in a service vehicle. Catastrophic leak into a confined space during service are also an issue.
There will be several component changes from the standard 410a systems. Indoor Equipment Indoor equipment will require an active dissipation board and refrigerant sensor. In other words, if refrigerant is present then equipment operation will be interrupted and the indoor fan will be energized to keep refrigerant below its lower flammability level dissipating refrigerant. It will also have an updated wiring diagram. The TXV will be designed for R 454b. New safety labels will be apparent throughout the indoor equipment. The evaporator coils will have straight liquid and vapor lines on all tier to allow brazing or press or mechanical fitting use. The liquid and vapor lines will be extended longer to allow for these changes as needed for your installation.
On the outdoor unit, the new compressor will be designed for R454b. It will also have a new A2L design contactor. The new A2L contactor will have a top cover with a small hole to access push button. There will be minimal air gaps inside the contactor to act as a flame arrestor. There will be wire sleeves on the high voltage wiring on the compressor. The compressors will have enclosed molded plugs and provide the necessary isolation from ignition. Wire sleeves will be installed on the compressor and crankcase heater wiring to mitigate potential ignition points. Pinch points are carefully assessed at the factory. It also will be having new safety labels throughout the outdoor system. Straight service valves on all tiers to allow brazing or press fitting use also. Red caps will signify the new R 454b and also installed to alert installers of something different.
Yes, there will also be some changes. There will be several new installation practices needed. We need to make sure the disconnect box is not mounted on the unit.
On the indoor unit, the sensor comes factory installed for vertical orientation, the location will be clearly identified for other applications. You will need to connect Y/Y1 from the mitigation board to the thermostat connections. For furnaces only you will mount the mitigation board to the side of wall of the furnace. Connect G from mitigation board to furnace control board. Connect 24 v power to mitigation board. Use the mitigation board self-test button to test the connection.
There will be a 10 second sensor warm up delay. Thee will be a self-test button with a 60 second mode. It will have a green LED for normal operation, and a red LED for mitigation mode. Safety chain interrupts Y/Y1. The blower stays on for 5 minutes after the sensor readings are below mitigation. Sensor over temp sends unit in mitigation mode. This allows heat pump heating or colling call after 15 minutes of mitigation. The blower is always on in this mode.
It is also well noted that Carrier/Bryant approved electric heaters are not considered an ignition source.
We covered pressures in past newsletters, but it is necessary to bring this subject up again while we are communicating with new techs in this artilcle about R 454b. Let’s compare operating pressure vs. saturated temperatures. If we have a saturated suction temperature of 40-degree Fahrenheit. The suction pressure of R 410a equals 118.8. With R 454b, the suction pressure will be 113.3. If we have a saturated condensing temperature of 110 degree Fahrenheit, the condensing pressure of R 410a will be 366.4 psig. The R 454b will be 349 psig. So these pressures are definitely not the same, but a small difference.
There is much more information forthcoming relating to R-454b. We are on scratching the surface. Stay tuned for much more in future newsletters.
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Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion.
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