Friday, April 28, 2017

Measure System Capacity and Efficiency

System tune-up time is here. Imagine if you could give your customers a report that shows the system capacity and efficiency before and after your system tune-up! There is a tool that can do that, the iManifold. It not only can measure system characteristics such as pressure, temperature, superheat, and subcooling; it can use the measurements to determine BTUs/hr capacity and system EER. To be sure, you need a few other measurements; namely, dry bulb and wet bulb in and out of the evaporator as well as system operating voltage and current. The iManifold with the correct accessories can measure the characteristics necessary to do system capacity and efficiency calculations and perform the calculations. It can also produce reports showing the details, including system capacity and efficiency. The report can be printed or e-mailed to the customer. The only “report” most customers get now after a traditional system tune-up is a bill. The iManifold and iConnect are the only tools I know of that can do this.

What accessories do you need? You also need two wireless temperature/humidity probes made to work with the iManifold and an electric meter that can communicate with the iManifold. The iManifold and the necessary accessories required to measure system capacity and efficiency are definitely more expensive than many other digital gauges. However, the iManifold does things other digital gauges cannot do.

To learn more about the iManifold chaeck out their web site imanifold.com


Friday, April 21, 2017

Don't Make the Problem Worse

There is a saying that if the only tool you have is a hammer, every problem looks like a nail. Many inexperienced techs make the mistake of trying to fix everything using the handful of procedures they are familiar with.

The most common “fix” applied to many systems is to add refrigerant. If a system is operating with low pressures or freezing up, many techs will add some refrigerant. Homeowners often actually ask for techs to add refrigerant, thinking that more refrigerant must mean colder air. However, adding refrigerant may not actually fix the problem. In fact, often it may make things worse.

For example, if a system has low airflow it will have low pressures, and often will freeze up. The reduced load will cause low superheat and refrigerant floodback. Adding refrigerant just makes the floodback worse, shortening the compressor life. An undercharged system would have a high superheat. You should always check the system airflow, superheat, and subcooling before adding refrigerant.

Another common example is a system with a refrigerant restriction, such as a plugged up filter drier. Again, both pressures will be low, and BOTH the superheat and subcooling will be high. This can look similar to an undercharge, except for the subcooling. An undercharged system will have a low subcooling. Adding refrigerant fills up the condenser, raising both the high side pressure and the already high subcooling. It may marginally improve the low side pressure and capacity. However, it forces the system to run at an excessive compression ratio and uses lots of power trying to force the refrigerant through the restriction. A far better solution is to remove the restriction.

Finally, a clogged or stuck expansion valve behaves like a refrigerant restriction. Failed expansion valves used to be quite rare. Unfortunately, they are pretty common today. Between the valves that were fouled up because of the compressor manufacturing problem and the valves that become clogged with black copper oxides, failed expansion valves have become all too common. The symptoms are identical to a refrigerant restriction: low pressures, high superheat, and normal to high subcooling. If someone has already tried to “fix” the problem by adding refrigerant, then the high side pressure may be high and the subcooling will be very high.

Please don’t make the problem worse. Before adding refrigerant to a system with low pressures, first check: airflow, superheat, and subcooling. A truly undercharged system will have adequate airflow, a high superheat, and a low subcooling. And if the system is undercharged, then maybe you should try to figure out why.

Sunday, April 9, 2017

How Much Refrigerant Does it Take to Make the Fan Blow Harder?

My brother Richard sometimes finds himself helping younger technicians who are stumped and need the help of an experienced professional technician. However, they have to really need help because they know Richard is going to twist their tail a bit in the process.

One day a frustrated tech called and told Richard that he was working on a system with a low suction pressure that was frosting up. He further explained that his new digital gauges were telling him that the superheat was 0, so he added refrigerant. However, no matter how much refrigerant he added, the superheat would not increase.

Richard asked him, “how much refrigerant do you have to add to make the fan blow harder?” There was no response, so Richard asked again, “Tell me, I really don’t know. How much refrigerant does it take to make the fan blow harder?” Finally, the tech responds: “Your question makes no sense! There is no relationship between the amount of refrigerant in the system and how hard the fan blows.” Richard then replies “So why are you trying to fix an airflow problem by adding refrigerant?”

While it is true that an undercharge can cause an air conditioning system to frost, the most common cause of a frosting air conditioning coil is actually low airflow. Always look at airflow issues first when trying to remedy a frosting air conditioning system. Common airflow issues include a dirty air filter, a dirty evaporator coil (caused by dirty air filters), closed registers, and poor ductwork.

One tip-off is superheat.  A system with airflow issues will operate with a low superheat while an undercharged system will operate with a high superheat. Note that if the coil is frozen over it will need to be defrosted before any pressures or temperatures are checked. The ice covering the coil makes its own airflow restriction.

Wednesday, April 5, 2017

PHCC Scholarship Deadline May 1

Could you use another $1000 to help with your HVACR Education? The Plumbing, Heating and Cooling Contractors (PHCC) are handing out money! Specifically, PHCC has announced that the deadline to apply for a PHCC Scholarship is May 1st. The PHCC has 41 different awards totaling $87,500 to give to deserving students. Each awrd ranges from $1000 - $5000.

Eligibility Requirements For All Applicants

  • A minimum cumulative grade point average of at least 2.0 for my previous academic work.
  • A citizen of the United States or Canada.
  • Have not previously won a scholarship from the Foundation. 

There are Scholarships for Apprentices, Technical School Students, and Students working towards a Bachelor's Degree

Apprentice Requirements

  • You are or will be enrolled in an Apprentice Program
  • You are or will be will be enrolled this year in a plumbing or HVACR apprentice program.
  • You also work full-time for a licensed plumbing or HVACR contractor who is a member of the Plumbing-Heating Cooling Contractors—National Association (PHCC).
  • Provide the PHCC Member Company Name, City & State:

Note: A max. of four employee scholarship applications per company will be accepted for consideration per year.

Community College and  Technical School Student Requirements
  • You are or will be enrolled in a Community College, Trade or Technical School
  • You are or will be enrolled this year in a full-time degree or certificate program at an accredited two-year community college, technical college or trade school.
  • You are or will be enrolled in an approved major directly related to the plumbing-heating-cooling profession.
  • Approved majors are: business management; construction management specializing in mechanical construction; HVACR installation, service or repair; mechanical CAD design; and plumbing installation, service or repair.*

Note: The PHCC of Massachusetts & PHCC of Texas Auxiliary scholarships have no restrictions on course of study.

Four Year College Student Requirements
You are or will be enrolled in a Four-Year College or University
You re or will be enrolled this year in a full-time undergraduate degree program at an accredited four-year college or university.
You  are or will be enrolled in or will be enrolling in an approved major directly related to the plumbing-heating-cooling profession.
Approved majors are: business management; construction management or science, specializing in mechanical construction; and mechanical engineering.*
Note: The PHCC of Massachusetts & PHCC of Texas Auxiliary scholarships have no restrictions on course of study.

Where to Apply

You can apply online here https://www.surveymonkey.com/r/PHCCScholarships
Or download and complete the pdf form found here
http://s3.amazonaws.com/rdcms-phcc/files/production/public/2011Foundation/PDFs/2017PHCCScholarshipApplicationForm.pdf