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

Sunday, February 26, 2017

Slow Times

I believe most of the United States is experiencing unseasonably warm weather right now. Here it is the end of February and friends in Chicago are going to the zoo, people are gardening in New Jersey, and here in Georgia folks are running around in shorts and tees. So, what are you doing with all the spare time? The warm February weather is nice, but it is not very good for business! I have a suggestion for your down time. When you get tired of cleaning up the shop and the truck, how about investing some time into education? Now that you have time, invest some time studying those things that you never have time to get to during a busy season. You can take classes or just do some self-study and research. It is very easy to get information now, so take advantage of your time. Studying during slow times is a great way to prepare for the future.

Saturday, February 18, 2017

Furnace Door Switch

One of the first things most technicians do when troubleshooting a gas furnace is to disable the blower door switch. The blower door switch kills power to the furnace when the blower door is removed. Since the controls and blower are in that compartment, it is impossible to work on the electrical controls with the blower door removed if you do not jump out or physically disable the door switch. Many folks use duct tape to keep the switch closed. Many techs don’t know why the switch is there, and some make their life easier by just removing the door switch altogether. This is a bad idea.

The door switch is there to prevent the blower from sucking in vent gasses and circulating them through the house. The suction created by the blower can be stronger than the draft created in the vent. If the furnace is operating in an enclosed space and with the blower door off, the fan can literally suck vent gasses out of the vent. This can cause two problems. One, the negative room pressure can interfere with the furnace getting enough combustion air, and two, the vent stops working – dumping combustion gasses into the room. This creates a situation where carbon monoxide can be created, dumped into the room, picked up by the blower and circulated through the house. This is especially true for furnaces that get their combustion air from space in where they are installed.

What about sealed combustion systems which draw combustion air from outside through a PVC pipe? Although the combustion air for a sealed combustion furnace normally comes from outside via the PVC combustion air pipe, if you remove the panel to the burner compartment, the furnace will be pulling air from the surrounding area. More to the point, the vent gasses could conceivably be pulled out through the burner area. Although not likely, if both panels are off it is possible for the blower to create a strong enough negative pressure to interfere with the combustion process even with a sealed combustion furnace.

So after working on a gas furnace make sure the door switch is functional before you leave. Do not leave it jumped out or mechanically defeated. You do not want to be responsible for a tragedy.

Friday, February 10, 2017

2017 National HVACR Educators and Trainers Conference

There is still time to register for the HVAC Excellence National HVACR Educators and Trainers Conference is this coming on March 27-29 at the Florida Hotel and Conference Center in Orlando, Florida. I will be speaking at the conference and will be at the Pearson booth at the Expo. Please come by and say hello. I love to talk with other HVACR Instructors. Not an instructor? No problem. Techs and contractors are welcome as well. You can pick up on many of the latest topics. Better yet, you can meet the dedicated people teaching HVACR. You really can’t find this amount of quality continuing education anywhere else for the price of these conferences. Come and fill up at the all you can learn educational buffet being offered.

If you can find a way to attend one of this conference you won’t be disappointed. They are well worth your time. Unlike generic teacher’s conferences that target all subjects, these are specific to our field. And unlike industry showcases like ComforTech or the AHR show, these are specifically for teachers. As a result, everything you see will have a direct application to teaching HVAC/R.

I know that times are tough and getting funding and permission to go is difficult. When presenting the idea to your school administrators be sure to forward a copy of the program from the conference. The sessions at the National Educators and Trainers Conference in Orlando are high quality, professional programs, not sales pitches. The presenters are nationally recognized speakers from respected HVACR organizations. Be sure to note the large number of educational sessions. There are literally more sessions than you will have time to attend. Point out that attending will keep you informed about emerging technology like communicating systems. Point out that by attending you will be better positioned to integrate green mechanical concepts into your curriculum as a result of attending the conferences. Your attendance is tracked, so you can prove the number of hours you attended. Finally, you can get enough free instructional material and tools to help your program. Come gorge yourself at the all you can learn buffet! Here is a link for more information about the conference