Field Notes on Air Conditioning and Heating
I have been in this field for the last 38 years, working on ships, buildings of all sizes, factories, warehouses, homes and on most equipment that required air conditioning, refrigeration and heating. There is very little I have not seen or worked on, many times. Here are some of the things I have learned.
What makes a good air conditioning technician?
The most important--experience. It takes five (5) years of working everyday in the field, doing service call after service call to become "good". That is someone who will be able to solve a problem more often than he is stumped. It takes ten (10) years to became an expert. By then, the technician has seen the majority of problems he will encounter in his career at least once. And for those he has not seen, he will have developed the skill of how to trouble shoot what went wrong.
Trade schools are not much help and for the high tuition they charge, really not worth the money. Books and self-study are better. The major manufacturers also offer short training courses from time to time, and they are helpful to learn their new equipment.
I have trained technicians at Ethan Clark and tried most every technique there is to get the man ready for the field. It is my conclusion, there is no trick or magic to it. Training is nothing more than having patience with the person, and sure enough, sooner or later, they get it. Trouble is, it does take years, even for men that do test out above average in intelligence.
Service work is incredibly detailed and the reason why it is impossible to teach in a school, or out of a book. Forget to tighten a wire in an electrical box and the job fails in short order. Forget to tighten a valve cap on a leaking access valve and all the gas will be lost in a few weeks. The list is endless as to what can go wrong.
Women would make wonderful technicians as they have a penchant for paying attention to details. This field is wide open to them, yet they are rarely found.
Why no one repairs window units anymore.
From the 1950's, to the 70's, one of the most popular forms of air conditioning was window units. The first luxury purchase a homeowner would make was to buy one. They were massive and cooled the whole house, although homes back then were much smaller than they are now.
Window units were well made and it was common to have them last 20 years or more. One famous brand--Friedrich--was made right here in Texas. They were also the best, in my opinion. I spent many a day changing compressors, fan motors, thermostats, heaters and fixing leaks as they were simple to work on and maintain.
What happened with window units? Well, homes were getting bigger and needed more than one window unit. And, window units could not compete with the quiet and comfort of central air conditioning. So people started moving toward central air conditioning and demand for window units decreased.
Once the downward spiral began, it accelerated. Manufacturers thought if they came up with cheaper units, they would sell more. They moved operations first to Brazil (don't ask me why they went there) and then to Mexico and Asia. They cheapened all the components, and got rid of most of the steel.
Today, you can buy a small brand new window air conditioner for $100. If you get 5 years of use out it, consider yourself lucky. Don't even think about having it repaired. They are mostly plastic, and if you can get one apart, you will never put it back together again correctly. Most parts are not available for them either.
Companies that used to specialize in window unit repairs are long gone. Economics is the reason. Who would want to pay $300 to put a new compressor into a window unit when you could buy a new one for the same price? No one. Funny though. I still get 4 to 5 calls every year, from people looking to service and repair them.
Texas Reheat--the finest air conditioning ever made!
It is often said, without air conditioning, Houston would not be the great city it is today. What really made Houston go up in stature was the Texas Reheat system of air conditioning. Few people have heard of it, but it was used in all the first office buildings downtown.
Here is how it worked. You ran a chill water system and a boiler, both at the same time. A chiller is an air conditioner that makes water cold. A blower would push air through a cooling coil and then immediately into a heating coil. The cooling coil would make the air very cold and in the process, all of the water vapor (or humidity) it had in it, would be taken out. You then regulated the temperature by reheating the air with the heating coil. Hence the name Texas Reheat.
The result was a perfect air temperature of 72 degrees F. and a relative humidity of 50%, 24 hours a day. When you went into one of those buildings, it was absolutely impossible to tell how hot, or cold or humid it was outside. It is the most beautiful air conditioned environment you could imagine.
People would come down from Northern cities like Chicago and New York and marvel how pleasant, Houston was in the summertime. They would say, the weather may be lousy in Houston in the summertime, but those people really know how to air condition a building.
I remember the first time my boss sent me out on a call with another fellow to go work on a boiler in July. I quietly thought to myself he was "nuts". The temperature was close to 100 degrees F. outside and we were going to work on a boiler? Sure enough when we got to the building, the people were so happy to see us. It was freezing inside with temperatures in the low 60's. No one could do anything but sit there and shiver.
The Texas Reheat system has faded into obscurity. I know of only two places in Houston that still use it. High operating costs are what killed it. You have to run a large boiler and chill water system both at the same time. Houston was the only city that used it a lot, as electricity and natural gas prices were low at the time, in this part of the United States.
Why some rooms are hot while others are cold in the summer
One concept most people have difficulty in understanding is how air is moved through a house. It is pushed through, not pulled or sucked.
You might try this experiment as proof. Take and light a candle. Now hold it two feet away from your mouth. Try and suck the candle out. It's impossible. When you blow on it, just a little puff of air and the light is extinguished.
So it is with air conditioning in a home or office. If a room is hot, there is not enough air being blown into it. And if it is cold, in the summer, too much air is blowing in it.
If you have this problem, check and make sure the damper to the room is either open or close, depending on what you want. You would be surprised how many people had shut off a damper years ago and forgot about it.
Sometimes you can fix the problem by adding dampers to the duct work if the duct work is accessible. Other times the size of the duct work has to be increased so the room gets enough air. If the duct work cannot be reached at all because it is behind sheet-rock, the cost to repair would be prohibitive.
Understanding how humidity and heat affects us in Houston
Humidity is the amount of water vapor, air can hold. When the weather-man says the humidity level is at 70%, that means the air is holding 70% of its total water holding capacity. In a cubic meter of air at 90 degrees F., 70% humidity would amount to 9.5 grains of water which is equal to .02 ounces. If the humidity is at 100%, it is raining.
.02 ounces of water doesn't sound like much, so how do you get 7 inches of rain like we do in Houston, from such a tiny bit of vapor? Simple. Water vapor has pressure and as soon as it is taken out of the air, it is immediately replaced with more. In theory, it could rain until the entire Gulf of Mexico is emptied out and then some more. There is no limit to replacing the water vapor.
Air also has elasticity which means it will stretch or contract, with the temperature. As it heats up, it will hold more water vapor and when you cool it down, it has to get rid of some of that vapor. That is the principle behind all air conditioning systems.
Normal human bodies operate at a temperature of 98.6 degrees F. We have to constantly get rid of our body heat or face the consequences. When it gets a little too warm for us, we perspire. Under the right condition, that perspiration will evaporate and cool us in the process. However, if the humidity is high, our perspiration will not evaporate and that will make us uncomfortable.
When the air conditioning system pulls the humidity out of the air of your home, it is immediately replaced from the outside, because of water vapor pressure. Water vapor will come into the house, through the tiniest crack. Just opening the door for a few seconds will allow it come in. Water vapor pressure is a powerful force.
Besides the humidity, we have the heat to contend with in Houston. Even if the humidity level were at "0", when the temperature starts getting into the 80's, it feels hot to us. People in Arizona laugh when visitors go out there and tell them even though it may go to 110 degrees F., it is a "dry" heat. Their answer is--"it is still roasting hot at 110 degrees F.!" Same thing in Houston, when it is hot, it is hot.
Can you live in Houston without air conditioning in the Summertime? Of course you can if you want to do what they did before. Close down all the businesses at noon or so, go home and try to cool off, then reopen at 5 or 6 o'clock in the evening. Some people think if they tough it out, they will get used to the heat and humidity. Our body metabolism is permanently set and when we can't get rid of the heat, it becomes unbearable. You will never get used to the heat or humidity, physically. It is a biological impossibilty.
It is both the heat and humidity that affects us. You may be interested to know, Houston is the second hottest place on the face of the earth in the summer. The only place worse than here is the Persian Gulf. There, they have temperatures as high as 120 degrees F. with humidity at 80%. Air conditioning equipment has difficulty staying on, under those conditions.
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