How it Works
Understanding the Refrigeration Cycle:
Superheat is the temperature of a vapor above it's boiling point and Subcooling is the temperature of a liquid below it's boiling point. Boiling point is also known as Saturated. As a change of state occurs vast amounts of heat called latent or hidden heat are either absorbed or rejected. Changes of State: From a gas to a liquid heat is rejected (condenser). From a liquid to a gas, heat is absorbed (evaporator). Understanding these two terms is key, however they are only the tip of the proverbial iceberg.
Sound Complex? Frankly the refrigeration cycle is very complex and it takes most Tech's a few years to get a grasp of it. Many Tech's never get it, just ask them. What was my systems Superheat and Subcooling? Understanding how superheat and subcooling applies to the refrigeration cycle the tech will know where the refrigerant is or isn't. Knowing where the refrigerant is or isn't, the tech can then determine what component is having issues, and how to properly charge the system. I have included a graphic of the refrigeration cycle that I created for my students when I taught at the VOTECH school.
Discharge from the compressor is a high pressure HOT superheated vapor which enters the condenser. The condenser begins rejecting heat to the point of saturation which begins a change of state from a vapor to a liquid. The condenser continues rejecting vast amounts of heat through out the change of state until the final change of state occurs and there is no more vapor. The condenser continues rejecting smaller amounts of heat which subcools the liquid below it's boiling point or point of saturation. Higher Subcooling means MORE liquid is present in the Condenser Coil.
Liquid passes through the Metering Device into the Evaporator which causes a pressure drop. This pressure drop causes the liquid to boil and begins another change of state this time from a liquid to a vapor. The Evaporator adds vast amounts heat to the Saturated liquid causing the liquid to evaporate until the final change of state occurs and there is no more liquid. The evaporator continues to add small amounts heat to the vapor causing it to be superheated. Higher Superheat means LESS liquid is present the the Evaporator, it is the opposite of Subcooling.
The COOL superheated vapor from the Suction line enters the compressor which Increases the pressure and adds the heat of compression in addition to some heat from the electric motor, and this HOT superheated Vapor leaves the compressor and enters the Discharge line completing one cycle.
Sounds misleading but the superheated vapor returning to the compressor is actually COOL. This cool vapor is how the compressor is cooled. If your system is low on refrigerant the superheat is high, the vapor is warmer and the compressor will run HOT. A hot compressor overheats, the refrigerant oil breaks down, the compressor life is shorter. Just a 25 degree Fahrenheit increase in the vapor returning to the compressor will cause the compressor to run very hot. At the compressor discharge line the temperature of the Refrigerant is the warmest. As the Refrigerant moves through the system it cools down. At the compressor suction line the temperature of the Refrigerant is the coolest. Heat always moves from Hot to Cold.
Having your system annually checked in the Spring will reveal if your system is improperly charged or has other issues at the time of service. Repairs can be made before your system runs in a low refrigerant state which can cause costly repairs and down time.
NOTE: for the Chart above: The F.C.S (Final Change of State) pointers represents the level of Liquid in the Evaporator and Condenser. 5 - 15 degrees represent the approximate acceptable superheat and subcooling levels of liquid in the system.
How Insulation Works
How is the insulation effect created?
The answer is simple and once you understand the fundamentals, the choice of which insulation to use will become clear.
Heat moves is 3 basic ways and always moves form hot to cold.
Convection: Warm air rises and cold air takes its place. People often say heat rises which is not true, it is warm air that rises. Imagine you are standing at a campfire. You see the smoke rising upwards with the warm air and if you kick up a cloud of dust just outside of the campfire you see the dust cloud being drawn into the fire. You are watching a visual effect of the convection process.
Radiant: Heat energy travels through space and air without giving up its heat energy until it strikes a solid object. The darker the object the more heat energy that object will absorb, the lighter the object the more heat energy will be reflected off of that object. Imagine the campfire again and as you are standing there warming yourself, your backside becomes cold. You turn around so that you can warm your backside, then your front side gets cold so you turn around facing the fire again. The closer you are to the fire or the heat source the more intense the heat energy. This is an example of how radiant heat works.
Conduction: Heat will move through objects by conduction, just as electricity moves through a conductor like a wire. Conduction can be slowed by an insulator just like wiring which has insulation on the outside keeps the electricity inside the conductor and prevents the electricity from shocking us. Look around you; do you see both a wood object and a metal object such as a desktop and a metal filing cabinet? Touch the wood object with one hand and touch the metal object with the other hand. Which object is colder? You just picked the metal object didn’t you? If you were to measure the temperature of the both objects they would be the same, but the metal object feels colder because it is a conductor and the wood object feels warmer because it is an insulator. Try this same test with wood and glass, the results are not as dramatic but the glass feels colder.
Now that we understand how heat moves we can look at what makes a better insulator so that we can keep the warm air or cool air that we paid for in our home as long as possible.
The insulation Effect occurs when pockets of dead air (trapped air) have been created. Each pocket will slowly give up its heat to an adjacent pocket until the heat has moved through out the pockets of dead air toward the colder space. Smaller pockets equals MORE Pockets. There is less convective movement of air in smaller pockets. An insulation with more smaller pockets tends to perform better.
The R-Value of Air based insulation, meaning insulation that uses air in the dead air pockets has a maximum of 4.0 R-Value per inch of thickness. Fiberglass, Cellulose, Rockwool, Mineral wool, Vermiculite, Blue jeans or denim, asbestos, etc. are examples of air based insulation. Foam insulation when new can have a 5.0 or higher R-Value per inch because the pockets have a gas in them other than air. The gas that causes the foam to expand from a liquid and cure into a solid has a higher R-Value similar to Argon between window panes provides a window with a higher R-Value. Studies have shown that this gas slowly escapes and is replaced by air over a 20 year period, which leaves the foam with a maximum R-Value of 4.0 per inch after about 20 years. R-Value stands for Resistance value the higher the resistance the better however R-Values alone is not a good way to judge insulation performance. Other factors play a major role in performance such as Air infiltration also sound and thermal mass also have effect on the performance of insulation.
Air Infiltration simply put is air leakage. If your car tire was leaking air you have to stop and add more air to keep the tire inflated so that you can drive on the tire. The larger the leak the more often you have to add air. Keeping your home warm or cool is similar to the tire, you have to keep adding or removing heat to the home to keep it comfortable. Insulation in your home only slows down the heat transfer it can not stop it. The amount of air leakage or air infiltration has a huge impact on a homes heating & cooling requirements. A new home insulated with fiberglass typically has an air infiltration factor of 1.0 or higher which means every hour 1.0 air changes occur. That equals 1 complete exchange of air every hour. A new home with cellulose insulation typically has an air infiltration rating of .3 meaning .3 air changes per hour. It takes about 3 hours for a home insulated with sprayed cellulose to have one complete exchange the air. A new home with sprayed foam insulation is about .2 or less air infiltration rating, taking about 5 hours or more to have one complete exchange of air. Older fiberglass homes can reach 2.0 or higher. If you have a fireplace add 1.0 to the air infiltration factor for each fireplace no mater how your home is insulated. A 2500 square foot home having a 1.0 VS .3 air infiltration factor the heat loss is about 12,000 Btu's per hour more at design temperature. The difference between .3 VS .2 is about 2000 Btu's per hour. A loose home has a 1.0 or greater air infiltration rating and a tight home has a .5 or less rating.
Indoor Air Quality also known as IAQ. This single issue of IAQ is perhaps the most important issue when considering how we insulate our home. Unhealthy, stale and stinky air can develop in a home which is too tight. Proper air changes are required to maintain a home with good and healthy IAQ. Air changes allow for the carbon dioxide we exhale to be replaced with fresh air and with oxygen which we inhale, along with many other things that are in the air such as out gassing of carpet furniture and adhesives used in the construction of our home. If our home has a 2.5 or less air infiltration factor we should exchange the air mechanically by Ventilation in order to have a healthy environment safe to live in. Equipment manufactures make Mechanical Ventilation Heat Recovery (MVHR) devices to improve IAQ. The MVHR equipment has an initial cost, requires energy to operate, special filters to be replaced and regular maintenance in addition to the cost of heating or cooling the fresh air that is vented into and out of our home. MVHR equipment will cost about $1500 or more to have installed. Consider this very important fact there is a economical line when crossed that will cost us more money every month because we got our home too tight. We will have to continually spend money to operate and maintain our MVHR equipment to keep our IAQ healthy in addition to the extra money we spent on insulation and sealing to get our home too tight to begin with. If we have poor IAQ and we don't invest, operate and maintain our MVHR equipment, how much money will we spend on medical bills because we live in a home with unhealthy air? How much will poor IAQ in our home decrease our quality of life?
Thermal Mass is another consideration of heat movement. Thermal Mass is not an insulation it is heat Storage. The greater the Mass the greater the Amount of heat that is stored within that mass. Water and concrete are very dense and therefore have greater potential to store heat. If we placed in two identical sealed containers both at the same temperature water in one container and air in the other container the water will stay warm much longer, because of the Thermal Mass of water compared to air which has very little thermal mass. It takes time for objects high in density or thermal mass to absorb heat and it takes time for that same object to give up its heat. Example: large tanks or 55 gallon drums painted black are often used in greenhouses to absorb radiant heat from the sun during the day and because the water is high in thermal mass they will give up or reject that heat throughout the night helping to heat the green house. The next day the cycle repeats.
So what are some of our choices and how do they compare?
Cellulose Insulation is a well known and widely used product. It is a post consumer product made from recycled newspaper and cardboard which is made from wood pulp a natural hollow fiber. Newspaper is ground in a mill (uses small amounts of energy to manufacture) and treated with a fire retardant. Some cellulose manufactures use additional materials in their products such as adhesives and pest deterrents.
- Low Cost material that can be applied by spraying into open wall stud cavities and attics. Custom fit into each stud cavity eliminating gaps and voids.
- Cellulose out preforms fiberglass about 40%.
- Wood is a great thermal insulator.
- Hollow fibers provide consistent sized tiny dead air pockets.
- Eliminates Drafts because air won’t easily pass through cellulose insulation.
- Cellulose has a greater thermal mass than does fiberglass or foam.
- MVHR equipment is typically not required.
- Saves space in our landfills.
- Uses post consumer materials and very little energy to manufacture.
- Fibers don’t cause skin irritation.
- Mice and insects will NOT nest in the treated cellulose.
- Cellulose insulation acts as a fire retardant, dramatically slowing the progression of a fire.
- No vapor barrier is needed.
- Great sound barrier.
- With the best cellulose insulation mold is proven not to grow in it.
- Cellulose proven performer, out performs fiberglass nearly 40%.
- Cellulose is Very Green for our planet and our budget.
- Overhead applications are not as easy as fiberglass.
- Slightly higher cost to install than fiberglass.
- Requires special equipment to install.
Fiberglass Insulation is the most well known and widely used product. It is a man made solid fiber which is basically made from silica (sand) and other materials. The base material is heated to the melting point which uses a tremendous amount of energy, and then the molten material is extruded through small holes where it then cools to form a solid fiber. These fibers are then treated with a binder (adhesive) to form batts which are then cut to standard sizes, packaged and ready for installation.
- Low Cost batts can be easily placed overhead between joists and rafters
- and in stud cavities.
- A knife and stapler is all that is required to install fiberglass.
- MVHR equipment is typically not required.
- Each batt has to be cut to size and properly positioned with no gaps or voids. 3%-5% gaps and voids reduce overall effectiveness 35%-50%. Studies have shown that the actual measured gaps of the installed batts are far greater than the 3%-5%. This proves that proper installation of batts is not easy to do and batts are typically installed incorrectly. An R-13 batt incorrectly installed does not perform at R-13 more like R-6 or less.
- Produces toxic fumes when burned.
- Glass is NOT a great thermal insulator.
- Irregular shape and large size air pockets occur on the outside of the fibers.
- Drafty, Air easily passes through fiberglass (some furnace filters are made of fiberglass).
- When sheet rock or paneling has to be removed from a wall you will see that the batts in those now exposed wall cavities are dirty the first 3 or 4 feet up from the bottom. The dirt is the result of the filter effect of fiberglass due to all of the air that has passed through the fiberglass and has filtered out the dirt.
- Some Fiberglass is now being manufactured to look like its dirty when new so that when it has aged and filtered a lot of air you won't be able to see the difference.
- Mold will grow on the dirt trapped in fiberglass from the filtering effect when conditions are ripe for mold growth.
- Fiberglass has a lower thermal mass than Cellulose.
- Fiberglass requires new raw materials and a tremendous amount of energy to manufacture.
- Fiberglas fibers cause itching, lung and skin irritation.
- Mice and insects will readily nest in fiberglass insulation and use it for a bathroom.
- Mice tunnels create even MORE gaps and voids further reducing the insulation's performance.
- Vapor barrier is required.
- Poor sound barrier.
- Fiberglass performance is poor.
- Fiberglass is not very green for our planet or our budget.
Note: Fiberglass can also be sprayed, bib and blown into cavities and attics. It improves the performance of fiberglass only slightly because it better fills gaps and voids make the voids smaller. However fiberglass is still made the same way and allows air to move through it.
Foam Insulation: Foam insulation’s are primarily made of 2 different materials, petroleum based or soy based. Foams use raw materials to manufacture and require a lot of energy to produce.
- Foam is a great thermal insulator.
- Foam has tiny cells that form dead air pockets.
- Air won’t pass through foam.
- Foam is a good performer, out performs fiberglass about 45%.
- MVHR equipment is required.
- Produces toxic fumes when burned.
- Do a YouTube search for "Foam insulation gone wrong" this is an eye opener.
- Foam insulation costs substantially more than fiberglass and cellulose insulation.
- Requires special equipment to install.
- Requires special personal safety equipment to install.
- Breaks down over time. (shrinks)
- Wall cavities generally are not filled leaving gaps and voids.
- This is done to minimize labor, the installer must cut off excess foam that overfills the stud cavity.
- Most foam installers will tell you "We don't need to completely fill the wall cavity".
- Do a Google search and look at sprayed foam images, you will see the cavity is not completely filled in they have large voids in the wall.
- When foam is being applied all other workers must leave the area because of strong toxic fumes.
- Areas not intended to be foamed require masking and plastic covering to prevent being damaged by foam over spray.
- Foam is flammable.
- Foam is a light green for our planet and our budget.
- Foam is not a great sound barrier.
Conclusion: Cellulose insulation is the best choice because of the initial cost, impact to the environment, and its performance thermally, acoustically, reducing air infiltration (drafts) and its thermal mass. When it comes to insulation, Cellulose insulation is the Greenest of the Green. However Not all Cellulose insulation’s are created equal. True the base products would be the same a wood pulp post consumer product but the extras that are added to the product will make a huge impact on the final products performance. For example Ammonia Sulfate is the primary fire retardant in the less expensive cellulose products. Ammonia Sulfate smells like urine and is corrosive. A product that has no Ammonia Sulfate but rather uses 100 % Boric Acid is a far better choice. Boric Acid is a common ingredient found in mouth wash, toothpaste, eye drops and Roach Proof insecticide. It is not corrosive and is a great fire retardant with the added benefits of insect deterrent. It is 6 times less toxic that table salt to humans. It does not smell like urine. How about an adhesive in the Cellulose? Products with adhesives will resist settling and will out perform a product that has no adhesive in it because it will maintain its thickness and R-Value. How about a fungicide in the Cellulose? Products with Board Defense an E.P.A. tested and approved ingredient will not allow fungi to grow on the cellulose even if the conditions are perfect for fungi growth. Can I have Cellulose insulation with all these benefits? The answer is YES you can! This is why Goodman Heating & Cooling exclusively uses Fiberlite Technologies, Inc products. We literally install the best insulation in the country.
WHY INFRARED RADIANT LOW INTENSITY (TUBE TYPE) HEATING IS THE BEST CHOICE FOR HEATING COMMERCIAL AND INDUSTRIAL BUILDINGS
In an infrared heating system the source of heat transfers its energy in the form of an electro-magnetic wave directly by radiation to whatever will absorb the energy, and this absorption results in a heating effect. There is no intermediate transfer medium such as air or water needed and fans are not required.
Perhaps the best example of infrared radiation is the sun. All the heat the earth receives comes from the sun in the form of infrared radiation. In reaching the earth these rays pass through a vacuum of space which does not absorb or alter the rays. When they strike the earth all objects absorb these rays and become warm. Infrared heat energy behaves much the same as light. But, instead of changing to illumination as a light source would, infrared energy is converted to heat.
To understand how radiant heat works and the substantial fuel savings and comfort levels that can result from its use it would be helpful to explain some of the fundamental factors involved.
First: Where a building is heated with a typical convection type heater such as a unit heater, the heat energy is distributed by high velocity air circulation at an elevated temperature. The inside surface temperature of walls, glass, etc. will be raised to a temperature somewhat higher than the surrounding air and will rise toward the ceiling. The resulting air temperature at the roof level will usually be very much higher than that at the floor level.
In the case of an infrared heating system, the heat energy is directed to the floor which absorbs the infrared energy. The mass of the building, floors, equipment, etc., become a very large heat exchanger or heat sink. This massive heat exchanger then re-radiates the infrared energy at a much lower temperature than would be experienced in the heat exchanger of a unit heater and does not have the buoyant effect found in a convection system.
The heat which is warmest at floor level and decreases in temperature as it rises will not raise the temperature of the walls and ceilings as happens with convection type units. Since the heat loss of a building is a function of the exposed surface times a “U” factor (measure of thermal resistance) times the differential of inside and outside temperatures it is readily understood that by maintaining a lower temperature of the walls, glass, and the ceiling the heat loss would be reduced considerably. In a typical application of this factor alone could reduce the heat loss 20 to 30 percent.
Second: there is very little air movement along exposed walls and ceiling. Since the convection part of the surface conductance is clearly affected by air movement, we may assume this will be reflected in the reduction of heat loss as it provides a measure of insulation without changing the construction.
Third: The comfort produced by the absorption of infrared rays (directly from the infrared radiation and from the mass of the building and its contents) is equivalent to a higher ambient temperature. There is less cooling effect on the body because air movement is greatly reduced over that which is experienced when heating air by convection methods. Most authorities agree that air temperatures of 5-7 degrees lower may be maintained with infrared systems to attain equivalent comfort levels.
Finally: Low intensity (tube type) infrared systems operate at relatively higher combustion and seasonal efficiencies that conventional convection heater. It is possible to have fuel savings of up to 50 percent or more.