Thursday, January 15, 2015

Perfect Weather for Defrost Problems

WE are experiencing  lot of cold, rainy days here in Georgia. The temperatures hover just above freezing into the mid 40's. This type of weather is perfect weather for heat pump defrost problems. Heat pumps have to defrost more in weather just above freezing than in much colder weather. If the temperature is so cold that water freezes out of the air, there won’t be much water in the air. If there is not a lot of water in the air, heat pump will not develop very much frost. On the other hand, if the temperature is 40 degrees and raining, there is a lot of water available. The coil in the heat pump will be below freezing even when it is 40 degrees outside, so the water will form frost on the coil. The system is more likely to need frequent defrosting at temperatures just above freezing than at much colder temperatures.  This is not to say heat pumps won’t got into a defrost cycle at very cold temperatures, but there is much less ice to defrost. The first thing to check on an iced over heat pump would be to make sure the outdoor fan motor is operating. If the outdoor fan motor is not moving air across the coil, it will frost very quickly in cold, wet conditions. The normal defrost periods would not be able to keep the coil clear. An undercharge can also make a system freeze up faster and keep it from clearing the ice when it does go into defrost. If water created when the coil is defrosted cannot drain away from the unit, a large ice floe can build up underneath the unit. This can create an ice chunk around the bottom of the unit. Heat pump condensers should be elevated enough to allow the water to drain. Sometimes the defrost thermostat just clips onto the coil. Occasionally they become loose and cannot sense the coil temperature, so they will not initiate a defrost cycle in weather that is above freezing. To check a defrost thermostat, just ohm it out. Generally, the defrost thermostat should close when it senses a temperature cold enough to initiate a defrost cycle. This can be checked by disconnecting the defrost thermostat from the circuit and ohming it out. If it is in the correct location, making good contact, and the coil is iced over, the defrost thermostat should be closed (0 ohms). If it is open (OL) it is bad. A thermistor defrost sensor is also checked by resistance, but these typically change resistance with temperature rather than opening and closing like a switch. You have to check the measured resistance against the manufacturer’s specs. Usually, these fail open, so if you have a measurable resistance, the defrost sensor is probably OK. Most defrost boards today have s test function. Jumping across the test pins accelerates time. If the defrost thermostat is closed, jump the test pins. If the board is good, it should initiate a defrost cycle. Do't automatically assume that the problem is a bad defrost board.Changing the board won't help if the problem is caused by one of the other causes.

Thursday, January 8, 2015

New Regional Efficiency Standards Take Effect

In case you missed it, there are now new minimum efficiency standards for residential air conditioning equipment. As of January 1, 2015 the long discussed regional air conditioning standards went into effect. They are called regional standards because the minimum legal efficiency of the equipment is determined by the region of the country in which it will be installed. For Northern states, nothing changes – the minimum stays at 13 SEER. For the southeast, the minimum is increased to 14 SEER.  For the southwest, the minimum is a bit more complicated. The SEER rises to 14, but minimum EERs are also introduced. The minimum EER for the Southwest is 12.2 for systems less than 45,000 Btuh and 11.7 for systems 45,000 Btuh and greater. So a 13 SEER system that is legal in Indiana is illegal in Kentucky. A 14 SEER system that is legal in Texas might not be in Arizona, depending on its EER. Although the minimum efficiencies are already in effect, the enforcement mechanism has yet to be determined.

It is interesting to note that it is possible for a unit to have a higher SEER than another unit, but for the lower SEER unit to have a higher EER. That is the reason for the dual SEER/EER conditions.
Rheem has a good page with a map and a table explaining the new standards

There is a very informative presentation on the California Energy Commision’s web site by Steve Kavanaugh explaining the reasoning behind using both SEER and EER for minimum efficiency standards.

Thursday, January 1, 2015

The Unexpected Gift

A little before Christmas I received a very unexpected gift. My son drove a couple of hours away to interview for a summer job. This was not just any job, but one in a summer camp in the woods – a bit off the beaten path. Later that day around 4:00 PM we got a call – he left the lights on, his car would not start, and he was unable to get it jumped. A friend offered to take him home, leaving his car there. We would need to retrieve the car later. At this point I was not exactly looking at this as a gift, but major nuisance. I could not be too mad because I have a tendency to do exactly the same type of thing. The next morning he and I got a new battery, loaded a bunch of tools in my car, and drove up to the woods to change the battery and get his car. Along the way we talked about his classes in college, world events, politics, and yes – car batteries. A two hour drive gives you a lot of time to talk. But truth be told, I enjoyed it. The battery in GM mini-van is in a horrid place: under the fuse box and a diagonal front brace. So there is a good bit of hardware to remove just to see the battery. I let him do most of the work – I just handed him tools. While we worked on the van I realized this was not a nuisance, but a gift. Instead of worrying about grades, curriculum, or schedules I received a day spent with my son. Priceless.

Saturday, December 20, 2014

Thank the Tool's Inventor

I love reading about the history of people who have made contributions to our industry. You might even say they have made major contributions to society. Think about a world without air conditioning, and then thank Willis Carrier. But contributions to society can be less grand than being known as the father of modern air conditioning. What about creating a tool which is used word wide every day? I would say that deserves recognition as well. It certainly does deserve my gratitude when I use the tool. We often use and take for granted tools and devices that someone before us created to make their life easier. They end up making life easier for a lot of us. They have made my word a better place.  Have you ever tried doing a job and NOT had the right tool? It is pretty frustrating. So when you use a tool that makes your life a bit easier and helps you accomplish more than you could without it, think about and thank its creator. I read a great article by Dan Holohan in the December 2014 issue of Plumbing & Mechanical magazine in which he traces the history of a very common tool, the Stillson wrench. If you are like me, you may be asking yourself – “What is a Stillson wrench?” I guarantee you have used one, only you might not know the correct name. You may call it a pipe wrench (as I often have.) Now think about how many pieces of pipe you have turned with a Stillson (pipe) wrench. How else would you have done that? It was invented by Daniel Chapman Stillson and patented by him on October 31, 1865. Next time you use one thank Mr. Stillson by calling it by its proper name, the Stillson wrench. He truly did make the world a better place.


If you want to know the back story on this incredibly useful tool, pick up a copy of the December issue of Plumbing & Mechanical magazine or visit their web site pmmag,com and read about the tool’s inventor.    

Saturday, December 13, 2014

Motor Frames by the Numbers

Two standards organizations publish motor frame standards: National Electrical Manufacturers  Association (NEMA) and the International Electrotechnical Commission  (IEC). Do you know why a NEMA Frame 56 motor is a 56 motor? I admit, until recently I did not. I just knew that if two motors have the same frame, they will mount in the same place. That does not necessarily mean that they are interchangeable, just that you can physically interchange them. However, I did not know what the 56 stood for in a 56 frame motor. It is really pretty simple. The number in a NEMA Motor frame designation describes the distance from the center of the shaft to the bottom of the mounting base in eighths of an inch. So a 56 frame has a distance from the center of the shaft to the bottom of the base of 56/8, or 7 inches. Of course, there are other dimensions that are set by frame size, but that particular dimension gives the frame its name. Maybe your machines use motors with IEC fame designations. The frame number still describes the distance from the shaft center to the base, but in millimeters. So an IEC 112 Frame motor has a distance from the shaft center to the bottom of the base of 112 millimeters. If you are measuring in centimeters that is 11.2 centimeters. As in the NEMA frame size, the IEC frame size standardizes many dimensions. Both standards have many dimensions that are described but not standardized. This means that manufacturer will report these dimensions, but they will not necessarily be identical from one motor to another. Baldor has a couple of good pdf reference pages which show the dimensions for each type of frame. You can find these at

NEMA  
IEC        

Saturday, December 6, 2014

Technically Speaking

Throughout my entire career in HVACR, technology has been changing how we work and what we work on. During this time, people have been continually complaining about the changes wrought by new technology. I can still remember an older technician in the late 70’s (yes I was actually working way back then). He was bragging in the parts house about replacing the primary control on someone’s oil furnace. It had a newer cad-cell type sensor which he did not understand, so he retro engineered the system to use a stack switch. Basically, he charged the customer to downgrade their equipment because he did not understand the controls. Another tech agreed, saying those cad cell things were not trustworthy. Then he added that he did not work on heat pumps – if a customer had a heat pump, they had to call somebody else. Today these guys would not be able to work – there just are not enough systems that meet their limitations. Many folks today don’t feel comfortable with communicating systems, but these systems are here to stay. In unitary product lines, communicating systems are still just the higher end. The thing is, most air conditioning manufacturers are offering them now. Virtually all mini-split, multi-split, and VRF systems use communicating control technology. And in case you haven’t noticed, those systems are here to stay as well. Sure, new technology can be a pain – especially brand new technology. Early adopters often pay a price for being the first with the new stuff. However, bitching about having to learn something new won’t keep the world from changing. You will just be left behind. As I age, I understand the pain of the old techs who just want to do the stuff they with which they are comfortable. I become less flexible both physically and mentally as I age, so I find it necessary to study harder to keep up with current field technology. As I see it, I have a choice – I can complain that the future will be different than the past, or I can work hard to keep up with changes in this field I love.    

Monday, November 24, 2014

Can-Do Versus Can't-Do

Are you a can do person or a can’t do person? Here is a way to find out. When presented with a challenge, do you start by looking for ways to get things done, or are you more focused on why it can’t be done? There are certainly obstacles to accomplishing anything, so identifying those obstacles is important in order to succeed. However, it is easy to focus on the problems so intently that you don’t allow room for any answers. Why should you want to be a can do person? In short, because can do people accomplish things. People who look for solutions persistently generally find them. They are often rewarded financially for consistently accomplishing things. Who do you want working on your behalf – someone with a track record of accomplishments, or someone who can point out all the reasons “it” can’t be done? People who look for obstacles seldom accomplish anything because they manage to convince themselves that “it” can’t be done. They are also rewarded accordingly. 

Another characteristic of a can-do person is the willingness to work beyond the minimum requirement. They will generally not be the first out the door at the end of the day and they take on extra duties or work without a lot of griping. By taking on new challenges, they are able to show their ability to do more than their present position. This can lead to promotions – and yes – financial reward. Can’t-do folks use such phrases as “they don’t pay me enough to…”, or “that is not my job!” They never demonstrate they can handle any more than their present position, so they never advance. I am not going to promote you and pay you more to see if you can do more – you have to demonstrate your ability to do more first. Again, if you need someone to help you, who are you going to ask? 

It is true that good workers are rewarded with more work to do. That is probably why 20% of the people do 80% of the work. That is often seen as a disincentive to work hard. However, these folks are also rewarded with promotions and financial incentives. They grow as a result of taking on more challenges. My father says that some people have 10 years of experience, while others have one year of experience 10 times. Again I ask – which one do you want working for you?  The good news is that having a “can’t do” outlook is not a genetic condition – it can be rectified. You CAN DO IT!