When All Else Fails — Read the Instructions?


As you all know, I have been saying this in past posts, training classes, and on site visits…. when all else fails, read the instructions.  Well, I have found out that this is not always the way to go. Now you’re saying WHAT?

What has brought me to this conclusion just happened recently.  I was on a site visit, and the contractor had actually “read” the instructions …. but he also “read into” the instructions because the manufacturer did not have specific information so he “winged it”.

This job was on a mini-split air conditioner. Because the manufacturer was not completely specific, the contractor got himself into trouble.

The first thing that got him into trouble was due to the fact that the unit comes charged for the outdoor section, the indoor section and 25 feet if interconnecting tubing.  In the instructions it provides a charge adder for any additional feet of tubing over that length. What the instructions DIDN’T say was if you had less than 25 feet, to remove the same amount per foot that you  use for the adder — common sense? Well, his job had only 16 feet of tubing. Since the instructions did not say to remove refrigerant, and the line set was less than 25 feet— he “followed what he thought the instructions were insinuating” and he didn’t remove any refrigerant.  So his unit was now overcharged. In his mind, he followed the instructions.

Next problem occurred because the manufacture put incomplete application information in the instructions. They listed the outdoor air on the condenser ( maximum 115 degrees dry bulb) but not the indoor air on the evaporator (minimum 70 degrees dry bulb). Now most of us know that air conditioners are designed with an indoor entering dry bulb temperature of 70 degrees.  If you want to go lower, you really need a refrigeration unit. Here again, because the manufacturer did not provide a specific, indoor application temperature, the contractor figured he could run the unit down to 64 degrees because the remote control allowed him to set that temperature. What he didn’t realize is the remote is used for both air conditioning units and also for heat pumps and that the high and low-end points on the remote are there for “set-up and set-back” temperatures for BOTH heating and cooling.  But, here again, the manufacturer was not specific so he assumed he could do it because the install instructions didn’t say he couldn’t.

So, between the 64 degree indoor air and the over charge with a cap tube metering device, guess what was happening — the indoor unit was freezing up. Isn’t that what you were thinking was happening?  This was both an installation and application problem that could have been avoided with complete information.

Now, I couldn’t get mad at the contractor because he DID READ THE INSTRUCTIONS. What he needed to realize is if it is not specific or if he felt something was not quite right, that he should have called the manufacturer (or someone) for clarification or guidance.

Now, I have reported these “short comings” to the mini-split manufacturer and, hopefully, the corrections to the instructions will be made but that probably will not occur until the  next  printing since all the inventory produced already has the existing instructions in them.

What contractors need to keep in mind is that most instructions are correct and the statement of reading the instructions is always the best way to go. Occasionally, there may be an omission but that is usually because the manufacturer assumes that common sense or general knowledge should prevail. Personally, I believe you can never have too much information but where do you draw the line?  Do install instructions need to be huge books? Then no one will read them. 

As it is, manufacturers now have to put all sort of WARNING and CAUTION, and DANGER labels both in the instructions and on the units.  It still comes down to EDUCATION and LEARNING. Had the dealer above really thought about it, he should have known that what he was doing was not correct and, even if he was unsure, he should have made that phone call.

So, I will again restore your faith in the statement — WHEN ALL ELSE FAILS, READ THE INSTRUCTIONS. — just be careful and question something if it is not there or does not make sense. And above all, remember, manufacturers are “human too” and can make an error of omission in the instructions. Hopefully, your experience and knowledge at this point, will help you make sure the installation and application is correct.

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About yorkcentraltechtalk

I have been in the HVAC industry most of my life. I worked 25 years for contractors on anything from residential to large commercial boilers and power burners. For the past 23+ years I had been employed by York International UPG Division ( a division of Johnson Controls) as a Technical support/Service Manager but I am now retired. One of my goals has always been to "educate" dealers and contractors. The reason for starting this blog was to share some knowledge, thoughts, ideas, etc with anyone who takes the time to read it. The contents of this blog are my own opinions, thoughts, experiences and should not be construed as those of Johnson Controls York UPG in any way. I hope you find this a help. I always welcome comments and suggestions for postings and will do my best to address any thoughts, questions, or topics you may want to hear about. Thanks for taking the time to read my postings! Mike Bishop
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4 Responses to When All Else Fails — Read the Instructions?

  1. Yakov Minster says:

    I thought that an over or under charge of 10% is OK. Was I wrong? 9 feet seems very little.

  2. I read your blog. Its simply super. You have very good content. See my blog alsoEvaporator Manufacturers

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