Non Condensables In A Refrigeration Circuit

Most of my laborious core studying got here within the early days of my profession.  I used to be thrown into many conditions I most likely had no enterprise being concerned in and like most younger apprentices, there have been quite a lot of royal f@#okay ups.  I keep in mind vividly, my first encounter with non condensables in a system and also you guessed it, I put them there or extra precisely, didn’t take away them.  

The Job

We have been putting in a 5 ton Liebert Challenger for a small server room.  The condenser was outfitted with an OROA flood again management, to construct condenser strain in low ambient situations.  The job went nicely for probably the most half but it surely did embrace a fall from a ladder, a compound fracture, a hospital go to and fusible plug that was by accident torched that melted the solder inside it, however these tales are for an additional day.  On the lighter aspect, myself, Carlos and Mike have been the set up crew and after I advised the boss in regards to the fusible plug incident he requested who torched it.  Rising up with the phrase, “snitches get stitches”, I advised him I would somewhat not say.  However, like most bosses he demanded to know.  My response, “nicely, it wasn’t me or Carlos”.  Technically talking, I fed Mike to the wolves however I by no means talked about his identify as soon as!  

The Begin Up

We have been on the again 9 approaching the 18th gap (evacuation of the system).  After pulling a vacuum in a single day we added a holding cost, pounding liquid into the liquid line till the system stopped accepting it. The ability provide was checked and verified as appropriate.  Upon preliminary begin up, instantaneous excessive strain fault and no it wasn’t a defective strain swap, the strain was truly 400 psi plus on the R22 system.  After a number of hours of this and that, I lastly made the decision to the workplace, I wanted some assist.  

The Grumpy Senior Tech

The grumpiest, however smartest of the bunch “tremendous tech” confirmed up and I used to be grateful as a result of I knew he would get the scenario sorted out.  After an hour or so of surveying the positioning and set up he went straight to the condenser mounted on the roof, caught a hose on the service becoming on the highest location and blew off about 30 seconds value of fuel (which I’m not recommending anybody do).  We went again all the way down to the indoor unit and began it up, now not did it immediately pop the strain management, it ran…however not so nicely.  He defined to me that there was air nonetheless within the system (non condensables).  I used to be dumbfounded due to our 14 hour evacuation.  It seems that on a system with a flood again management and liquid line solenoid valve, we should energize the solenoid throughout evacuation… If not, we can be unable to take away the air trapped between the 2 units.  All the cost was eliminated, the evacuation was executed as soon as extra, with the solenoid energized.  A recent batch of R22 was charged into the system and we referred to as it a day….A protracted day!  

What Are Non Condensables 

Non condensables are gases similar to air or nitrogen that may not be condensed in the course of the refrigeration cycle.  They transfer into the condenser and trigger points inside a system, however fortunate for us, these points have signs.

Signs Of Non Condensables 

We talked in regards to the elevated discharge strain, this is because of the truth that the non condensables are speaking up wanted area inside the condenser coil.  The elevated strain within the condenser will trigger increased than regular compression ratios as nicely.  As a result of elevated condenser strain and saturated condensing temperatures, the condenser temperature distinction or condenser break up may even be excessive (distinction between condensing temperature and ambient temperature).  Others issues to search for…attainable enhance of suction strain, excessive compressor amp draw and better than regular subcooling.  Use greatest pratice evacuation procedures to make sure all non condensables are eliminated for a wholesome working system.   

Some classes cannot be realized from books, you should breathe within the errors and embrace them as studying experiences.  Comfortable HVACing!

Try the hyperlink to my YouTube channel for extra suggestions, tips, and troubleshooting movies and take a look at the The HVAC Know It All podcast right here or in your favorite podcast app.  

Gary McCreadie

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