CAREER OPPORTUNITIES IN HVAC.

In the next five years, many HVAC technicians employed in the industry today will experience the same fate as the radio and television  repair technicians of the 70 s and 80 s. Today, every residential  repair application has experienced a downward trend in sustainability due to a shortage of skilled labor.

A new era in HVAC installation and repair started some 5 years ago and now is at full speed. The need for efficient building systems and regulated reduction in energy usage has driven the need for technological advancements in HVA

The need for real time information including what is happening at homes and also providing access to building information  has forced the introduction of controls for monitoring and controlling air-conditioners and other home appliances and utilities remotely. Today, a home owner can receive weather information from a wall thermostat; one can adjust set points, verify the condition of filters, turn HVAC systems on and off remotely. The systems are now able to verify their refrigerant charge, adjust air volumes, and maintain temperatures within a degree in every room. They can  decrease capacity at peak electrical usage times, and  provide diagnostics for more dozens of fault conditions.

For service and maintenance purposes the units operation can be started from the outside without access to the thermostat, or having to enter the home;  parameters can be obtained using onboard controls at the outdoor unit..

According to HVAC Excellence, 65.6 percent of service technicians in the HVACR industry will not be in the industry in eight years. The next generation of the industry should  now  be in the class room learning skills and approaches to match the demands of the ever-evolving market, and there is a growing sense of the need to recruit those who will serve as the technicians of the future.

Skills in Demand

Future HVACR technicians are busy learning tomorrow’s technology today. A growing desire for computer skills is apparent in the HVAC industry, just as they are in most other employment sectors.

David White, director, Advanced Robotic Technology, Brisbane, Australia, said every student with a technical aptitude has a desire to work with computers. We need schools to return to exposing kids to relevant industries where the scope for employment exists.

 

“The HVAC industry has a lot of computer-related areas including drafting, design, controls building management interfaces, manufacturing and more. We need to get  kids involved at a school level preparation for these  exciting and hands-on cereers so that they get the bug,” he said.
“There are now a lot of cool machines that take drawings and turn them into ducting and other components. We are finding that it is a real buzz for kids to actually produce something they can feel and touch from a computer drawing.”
Whole-home performance and energy-efficiency skills are also on the rise. Lincoln Technical Institute, Union, N.J., officials said their energy auditing certification course is currently attracting more attention than any other offering.
  HVACR curriculum council chair and education supervisor, Lincoln Technical Institute said “The future of the HVACR industry is based on the newer technicians’ ability to adapt and learn the industry’s latest innovations. As our industry evolves to a higher technological era, newer technicians will need to meet those advanced technologies with an open mind and sound HVACR knowledge.”
In addition to these new-world skills, Kevin Couch, HVACR instructor, R.G. Drage Career Technical Center, said young learners should not forget that the HVACR trade will continue to be based on old-fashioned, hands-on labor. Yet technological attractions will create the interest for young careers,
 
  All  of the skilled trades are facing a severe shortage; from bakers, roofers, stucco and plasterers, HVACR, electronic repair, electricians and plumbers, we all need skilled people,” he said. “Shortages specific to the HVACR sector reached that critical level a few years back. Why?  because all the vocational-tech schools shut their doors the world was going to be run by computers. Now, who can fix the furnace or air conditioners? No one, because no one wants  to do the manual work and we have not introduced our future work force to the controls being designed and installed in HVAC systems.

Recruiting the Next Generation
Industry members also stress that the combination of new and old skills needed — and the excellent career opportunities in HVACR — must be promoted in order to recruit more young people to the trade.

Steve Dodd, MEP advisor and director of service and energy, Fidelity Engineering Corp., Washington, D.C., referenced several new skills becoming relevant in the HVAC sector.
 “These skills include technology, intelligent devices, green, financial influence, stability, health effect, and more,” said Dodd. “First we need to educate guidance counselors as to these things since they start the influence process as early as middle school.”

Jeff Plant, general manager, Springfield Mechanical Services Inc., Springfield, Mo., believes HVAC work is more than just physical labor, and agreed that young students need to be aware of the many opportunities available in the industry at an earlier age
“The first thing people think of when they think of HVAC workers is the old labeling of the construction worker. Although that spot for installation and backbreaking work is never going to be replaced, there are many other avenues and opportunities that present themselves in this trade,” he said.

“If we want to attract younger people to this trade, we need to relate. Show them the wide array of opportunities that this trade offers. We as successful tradesmen need to visit the local high schools, help with  local apprenticeship programs and share our stories. 
“Today, students should  learn thermodynamics, mechanical, electrical, hydronic  principles, customer service, and sales skills,” we should return to past learning formats that served so well in preparation for the industrial age.

“We need to have technicians who can adapt to all the changes that have happened, and will happen in the those fields that hold promise for employment and enhanced quality of life.
 
Jules Williams
Building Analyst
MASHRAE.

40 EER air-conditioning efficiency achieved by Climate Master

40 EER achieved by Climate Master.

A Major achievement for air-conditioning efficiency is the announcement from Climate Master and certified by AHR that it has attained 40 EER the best efficiency in industry today.

OKLAHOMA CITY — Climate Master recently announced its Trilogy™ 40 series has exceeded 40 EER at ground-loop conditions and been certified by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI).

The Trilogy 40 utilizes variable-speed technology to provide a range of heating and cooling capacities, with the ability to perfectly match loads to as low as 30 percent of maximum. The Trilogy 40 Q-mode series is the outcome of five-year collaboration between Climate Master and Oak Ridge National Laboratory (ORNL), which was sponsored by the U.S. Department of Energy (DOE) Building Technologies program. Based on field tests and analysis by ORNL, the Trilogy 40 Q-Mode can save up to 65 percent of annual energy use and cost for space conditioning and water heating in residential applications versus new minimum 13 SEER conventional systems.
“Climate Master has a solid track record of leadership and innovation since its founding in 1957,” said Daniel Ellis, president. “We are very proud to continue that legacy with the launch of the new Trilogy 40.”
For installing and servicing contractors, the Trilogy 40 offers the technology needed to configure and diagnose the system electronically using communicating controls and sensors that monitor system operation to ensure peak performance.

 The Trilogy 40 Q-Mode represents a major breakthrough in comfort and efficiency,” said John Bailey, senior vice president of sales and marketing, Climate Master. “With variable-speed fan, pump, and compressor technology, plus four operating modes, it far exceeds the capabilities of any other HVAC unit on the market today. Plus, it can completely eliminate the use of auxiliary heat even in far Northern climates.”

Jules Williams.

Carrier Air-conditioning lunches home energy improvment program

BALTIMORE, March 27, 2012 /PRNewswire/ -- Carrier introduced its new Energy Experts program, a nationwide program focused on improving home performance and reducing home energy costs for consumers, today at the Affordable Comfort Inc. (ACI) National Home Performance Conference in Baltimore, Md. Energy Experts is a comprehensive home performance and energy assessment program for Carrier® Factory Authorized Dealers. The program will help consumers be more comfortable in their homes, reduce home energy consumption, and save money on utility bills. Carrier, the world's leader in high technology heating, air-conditioning and refrigeration solutions (HVACR), is a part of UTC Climate, Controls & Security, a unit of United Technologies Corp. (NYSE: UTX - News).
 Carrier Energy Experts will conduct home performance energy audits that typically analyze a variety of factors within the home, including the heating and cooling system, air flow and the home envelope (roof, windows, doors, insulation, etc.), and provide solutions to improve on the overall efficiency of the home.
 According to the Department of Energy's Buildings Energy Data Book, heating and cooling account for about 54 percent of a typical home's energy usage," said Matt Nuijens, Carrier brand manager. "Carrier Factory Authorized Dealers are already HVAC experts, so the Energy Experts program is a natural next step. Through the Energy Experts program, Carrier dealers will become knowledgeable on all areas of home energy conservation. They can conduct whole home energy audits and provide solutions to consumers that can save costs," added Nuijens.
As part of the Energy Experts program, the Carrier 360 Degree whole home energy audit includes a six-step assessment of the home, including inspection, testing, analysis, recommendations, resolution and results on the heating, ventilation and air conditioning (HVAC) system, air filtration/distribution and home envelope. Carrier Energy Experts will utilize state-of-the-art technology for the energy audit, such as thermal imaging cameras, blower door testing equipment or static pressure gauges. Following the audit, consumers are provided with steps to improve on home performance, through adjustments to home energy systems, including repair, upgrades or replacement of the heating and cooling and air filtration/distribution systems as well as the home envelope.
"For more than 100 years, people have been able to turn to the experts at Carrier," said Chris Nelson, vice president, sales and marketing, Carrier Residential and Commercial Systems. 

 "Carrier Energy Experts can provide homeowners with solutions that address the energy efficiency of the whole home, identify areas where you could be losing valuable energy, and provide a prioritized list of ways you can save on energy costs. It is another example of Carrier's commitment to energy efficiency, sustainability and customer service."

 Carrier is the world's leader in high technology heating, air-conditioning and refrigeration solutions. Carrier experts provide sustainable solutions, integrating energy-efficient products, building controls, and energy services for residential, commercial, retail, transport and foodservice customers. Founded by the inventor of modern air conditioning, Carrier improves the world around us through engineered innovation and environmental stewardship. Carrier is a part of UTC Climate, Controls & Security, a unit of United Technologies Corp., a leading provider to the aerospace and building systems industries worldwide

Jules Williams Building Analyst (BPI)

Federal Government allocate US$5.2 million for improving building efficiency.

Federal Government allocate US$5.2 Million  for improving building energy efficiency.

WASHINGTON — As part of the Obama administration’s blueprint for an American economy built to last, Energy Secretary Steven Chu announced the availability of up to $5.2 million in fiscal year 2012 to develop improved building efficiency technologies, including advanced heating and cooling systems and high-efficiency insulation, windows, and roofs. The funding will advance the research, development, demonstration, and manufacture of innovative building technologies to speed the commercialization of affordable, high-performance products that will save money for American families and businesses.

The Department of Energy (DOE) reports that homes and commercial buildings consume approximately 40 percent of the energy used in the U.S., costing American consumers more than $400 billion. Nearly a third of that energy is used for HVAC operations. Advancing HVAC building technologies and improving the design and materials that make up a building’s envelope, or air seal, will significantly reduce the cost to heat and cool residential and commercial buildings, while providing a tremendous opportunity to cut carbon emissions and reduce the nation’s reliance on fossil fuels.
DOE seeks applicants for up to $5.2 million in funding to support breakthroughs in energy-saving HVAC systems and building envelope solutions. Eligible mechanical HVAC system projects should aim to increase the efficiency of cost- effective systems and components suitable for both existing buildings and new construction. Eligible building envelope projects will focus on advancing high-performance, cost-effective, and attractive solutions to minimize energy loss in homes and commercial buildings. DOE is particularly interested in proposals for innovative technologies for use in existing buildings, especially if they can help accelerate adoption of energy-efficient building upgrades.
As part of a planned three-year initiative, Congress has appropriated $1.2 million for HVAC and building envelope projects that develop advanced manufacturing processes or equipment to help lower the life-cycle energy cost of manufactured products and improve the performance of energy-efficient building technologies. DOE plans to make additional requests totaling $10.8 million to Congress over the next two years to support these innovative building efficiency technologies.

Applications will be accepted through 5 p.m. Eastern time, April 17. For more information, visit https://eere-exchange.energy.gov/.

Publication date: 04/02/2012

Summer air-conditioning technical requirements

Summer Air-conditioning Concerns and Recommendations:

In a few short weeks many of us will experience summer heat and if this year’s weather is even close to last year’s with regards to hot prolong temperatures we know what to expect. One thought of comfort is the knowledge that most of us will have air-conditioning at work and at home. The reality is air-conditioning is a life saver when it works and a burden when it  does not additionally there is always concern for the cost for the energy used to operate the equipment.

Today’s air-conditioning, especially systems purchased in the last 5 years incorporate complex technologies. This poses a challenge for installers  and service personnel. Like earlier devices eg. radios, television and other residential and commercial equipment, the knowledge necessary for keeping electronic and electromechanical equipment operating has evolved greatly. Most air-conditioning systems in operation today use micro computer technology for operation in order to meet comfort, energy and regulatory requirements. Many systems use variable speed technology and direct current components to achieve energy efficiency. These devices have to be protected from electric surges, lightening and other conditions that would other- wise interfere with operation.

Systems that would normally be installed by  experience of installers,  now require software for estimating heating and cooling needs, comfort, noise, humidity, smells and air cleanliness. Renewable energy air-conditioners are on the market today with equipment designed to be powered entirely by sun or solar electricity.  Accompanying industrial development are issues associated with health and these issues are addressed with the use of air-conditioning.

The air-conditioning industry has  for many years attempted to address the need for a knowledgeable work force to meet the installation and maintenance needs of the air-conditioning industry. This effort has proven to be difficult since the average skilled worker needs 3 to 5 years of practical experience in order to be able to intelligently install and maintain today’s air-conditioning systems. Many of the technicians that show up at our houses have never obtained training outside the normal courses taught at general schools and colleges. More than 80% of these technicians have no idea of thermo dynamics and other necessary theories and principles necessary to properly recommend for sale, install, maintain and repair HVAC equipment and  most do not speak air-conditioning language. A company may employ for example 50 so called technicians, yet it would be a stretch to expect to find more than 2% who have a working knowledge of air-conditioning.

Many repair routine costs three to five times more  than the actual due to poor diagnosis, ignorance, faulty repairs, unnecessary replacement of equipment and high operating costs concluding repairs.

The need for intelligent evaluation of air-conditioning and other home repair personnel  has never been more warranting. Quick money making, a sluggish economy and poorly trained service personnel working in a life and death environment of high temperatures, humidity and allergies is a formula for disaster. Many of the organizations we depend on for company and personnel references depend on membership, sponsorship or advertising monies to finance their existence. This leaves customers with little comfort when their air-conditioning equipment does not work and are in need of trained personnel.

Here are a few tips to managing your next air-conditioning repair experience and mitigate the effects of less than competent service or installation technician.

When requesting installation of new equipment do ensure the following.

Ensure someone capable of observing and asking questions is at your  home or business to advocate on your behalf.

During installation do not interrupt the installer unless it is absolutely necessary to do so.

Prior to installation of equipment be sure to ask the installer to give you a brief description of what he or she is going to do.

Verify with the installer the equipment to be installed  is consistent with the paper work you were given at the time you signed the contract.

Verify the Model and SEER are what was sold and request the manufactured date from the serial number.

Ensure your home or business is protected for the installation work, that floor cloth cover your carpet and the workers have shoe covers when walking in sensitive areas.

Concluding the installation ensure the job looks neat, all pipes are supported,  no wires are exposed; no air is leaking at the equipment and no water is visible from pipes protruding from the structure. Request a test of the system from the thermostat. Have the worker place a thermometer at the thermostat and operate the equipment for cool. Use a timing device to indicate how much time it takes to decrease the temperature indicated at the thermostat. If it takes more than 5 minutes for a degree drop begin to ask questions. However ensure there is temperature drop before the worker leaves.

Request the following of the installer: What is the split? It should be between 15 and 18 degrees in that ball park. What was the sub-cooling, super heat and how much current is my system drawing.  What is the temperature at the  supply grill. The installer may give makeup numbers but he or she will know that you have knowledge that they should be concerned with. They may be more careful about taking short cuts.

Before the installer leaves  be sure to request all users’ manuals, contracts, warranties and related documentation consistent with your contract. Be sure all service material is left at the equipment or where they can be retrieved for future servicing. Verify all installation related garbage is removed and that there is no damage to your home.

Don’t turn off the equipment as soon as the installer leaves. Allow it to operate for about 8 hours and monitor for anything abnormal. Noises, smells, dust circulation, poor temperatures, poor comfort and lengthy or very short operating cycles. Document all service calls and maintain a log for every piece of equipment.

We will talk about Sales and Service specifically next time.

Jules Williams

MASHRAE Certified Building Analyst.

A home is comfortable when temperature and humidity is controlled.

 Comfort Cooling Controlling Humidity and Temperature.

An air- conditioner ability to remove moisture increases when the equipment runs for longer periods of time. At the beginning of every cycle in hot moist climates, the air conditioner puts moisture into the house as water is evaporated off the inside coil. Since a smaller air conditioner runs longer to keep the house at the temperature set point, it removes more moisture than a larger unit would be able to achieve.

A 5-ton unit, running for five minutes would remove 1.4 pounds of water. A 2.5-ton air conditioner, in the same house, running for ten minutes would remove 1.7 pounds of moisture. This is an increase in moisture removal of 21%.

The amount of moisture removed is not only a function of how long the air conditioner runs, but also it’s Sensible Heat Ratio (SHR - the percentage of the total capacity delivered as lower house temperature).

A low Sensible Heat Ratio will result in more moisture removal. For hot wet climates where moisture removal is important, air flow across the coil should be reduced slightly to increase the SHR and the air conditioner condensing unit and indoor coil combination should be chosen to have a low SHR. Please note, if you don't use the outdoor unit manufacturer's indoor coil, you cannot use their published SHR.

Typical matched units from major manufacturers have Sensible Heat Ratios in the 68% to 80% range when it is 95¡F outside and 75¡F with 50% relative humidity inside. Even Temperatures are Necessary for comfort. Some people don’t experience problem with moisture, but  have problems with uneven temperatures when the air conditioner was on

The following describes two methods contractors can use when attempting to get proper distribution and mixing of the air.

An old method is to use a large air handler fan to circulate air all or most of the time. This is sometimes effective in mixing the air but at a high price. There is an old rule of thumb that between four and six house volumes of air must pass through the air handler in an hour. At six air changes this means a 1400 sf. home would have to have a continuously running fan that delivers 1120 CFM (equivalent to almost 3 tons) regardless of the cooling load of the house.

The common practice is to install an air conditioner (inside and outside unit) with the capacity to meet those flow requirements.

• There are many disadvantages to this scenario:
• the need for a larger and more expensive duct system to handle the increased flow
• increased duct conduction due to constant circulation and the larger surface area of duct system
• reduced latent capacity due to constant circulation and short compressor cycles (caused by the oversized outdoor unit)
• increased cooling load due to duct leakage effects and fan energy delivered as heat

A better solution is, to design and install a delivery system that properly distributes the cooling to each room, then to select and place supply grilles that promote mixing by "throwing" the delivered air into the right places in the room. Air Conditioning Contractors of America has produced manuals to guide contractors in this process (Manual D-Duct Design and Manual T-Terminal Design).These Manuals lead the installing contractor through the process of selecting the proper size duct and type of register based on the location of the register, size of the room, restriction the duct run, and the dimensions and heat gain of the room. Unfortunately, only the best contractors and builders ever pay attention to these critical details.

The problems of stagnation and overheating can be reduced by proper implementation of ACCA procedures. These problems can be further reduced by ensuring that the assumptions built into these manuals are not violated. For example, it is assumed that there is no duct leakage in the system. Any long time reader of Home Energy will immediately note that this assumption is violated in nearly all homes (including new ones). Proper installation of the duct system and leakage testing are essential to obtain comfort.

Another assumption is that the conduction losses are the same percentage of the delivered cooling regardless of the length of the duct run. This would be an insignificant assumption in a heavily insulated system (and R-4 is not heavily insulated). Long duct runs through the attic loose over 15% of their cooling capacity before the conditioned air reaches its destination. Long duct runs need additional insulation to deliver the proper amount of cooling to the distant rooms.

Uneven temperatures have become more common due to the "modern" practice of severely reducing overhangs above the windows. Without overhangs, rooms with west facing windows will overheat in the afternoon since their need for cooling can easily double Drafts Destroy Comfort

A draft exists when unwanted air movement causes cooling on one part of your body. The colder the air and the faster it is blowing, the more offensive drafts are. Air conditioning drafts are characterized by cold, high velocity air striking your body. Studies show that these drafts are even more offensive if they are intermittent.

Oversized air conditioners are a major contributor to drafts. An oversized air conditioner is almost always married to a duct system that is unable to deliver the amount of air necessary for proper air conditioner performance (more on this later). The result is a poor compromise air flow that is too low for the air conditioner and too high for the duct system. The low air flow across the oversize coil produces colder delivery temperatures and the high air flow through the ducts and grilles produce high pressures, noise, and high velocities at the grilles. When low delivery temperatures are coupled with high velocity discharge through inappropriately selected (small and without proper throw or spread - often the cheapest) and poorly placed grilles, occupants experience drafts.

Bigger is not Better, Quiet is Better

We all know how noisy forced air cooling systems can be. These noises can come from the grilles, the ducts, and from the fan. Our perception of noise is affected by both the frequency and the level of the sound. Higher frequency sounds (the sounds generated by high discharge velocities at grilles) are more offensive than lower frequency sounds (the sounds generated by the fan). For grilles there is a Noise Criteria (NC) rating that mimics the human perception of sound. The NC for a particular grille increases as more air is forced through it.

When an air conditioner and duct system are properly is sized to meet the cooling load it is easier distribute the cool air without being noisy. When a duct system is being designed, the NC level and face velocity of every supply grille should be considered and held below NC-25 and 700 fpm for a quiet system.

Grilles with dampers are invariably noisier than equivalent grilles without dampers. When the dampers are partially closed, the pressures and leaks in the ducts increase and the air flow across the coil is reduced. Occupants generally close dampers to redirect air to another room that they believe needs more delivery. If the system is designed correctly dampers, either at the register or in line balancing dampers should not be needed.

Bigger is not Better, Efficient is Better

There is a lot of emphasis on the rated efficiency of air conditioners. Unfortunately, this necessary emphasis on equipment design has overshadowed efforts to improve the selection and installation of the entire air conditioning system. It is incorrectly assumed by builders, contractors, and the buying public that if you spend the money on a high efficiency air conditioner you have gotten all the efficiency you can. But common problems such as over sizing, improper installation, and low air flow, and leaky duct systems mean that customers don't get the efficiency they paid a premium for.

A System with Correct Air Flow Helps Make an Efficient System Most air conditioners are designed to have 400 CFM per ton of air flow across the inside coil. When the air conditioner is coupled with a duct system that meets Manual D criteria, the proper flow is achieved.

However, since air conditioners are commonly oversized for the heat gain of the home and the duct systems are not designed to Manual D even new systems are usually deficient in air flow. This situation only gets worse as the inside coil picks up dirt. In a recent laboratory test of a high efficiency air conditioner, Proctor Engineering Group found a 7 % drop in efficiency when the air flow was reduced by 30%. In order to ensure that the design air flow is being achieved, the installing contractor must measure the air flow across the inside coil.

An Air Conditioner with Proper Charge Helps Make an Efficient System A new split system air conditioner comes from the factory with the proper amount of factory installed charge for a standard length set of refrigerant lines. When the unit is installed, the contractor needs to evacuate the lines and indoor coil and weigh in any additional charge needed for the line set length increase over the standard length. Most of the time this is not done. This results in, leaks not being detected, air and moisture being captured in the line set and coil, and the unit ends up undercharged. In many cases the amount of undercharge is severe.

In the summer of 1995, Proctor Engineering Group and Arizona Public Service Company monitored a group of twenty two newly constructed homes.

Nearly all of those homes had undercharged air conditioners. One of the worst units had 62% of correct charge (and 79% of proper flow). The homeowner complained to the builder that the air conditioner was not working right. She was told that the wrong amount of insulation had been installed in her attic and an insulation contractor was called in to apply additional insulation.

Shortly thereafter the true problem showed itself when the air conditioner compressor failed. Eliminating Duct Leaks Helps Make an Efficient System The evidence against leaky and under insulated ducts continues to mount. Leaky ducts are a large contributor to system inefficiency and the negative effect increases with outdoor temperature. The Arizona Public Service Company test found that sealing a 13% supply leak saved 22% of the cooling energy consumption in the 100¡F to 105¡F temperature range.

To ensure a tight duct system the installing contractor will have to do a test of duct integrity using specialized tools. (See the Sept/Oct Î93 issue of Home Energy for more information on duct testing.)

A Smaller Air Conditioner Helps Make an Efficient System Air conditioners are very inefficient when they first start operation. It is far better for the air conditioner to run longer cycles than shorter ones. The efficiency of the typical air conditioner increases the longer it runs. For example, increasing the run time from 5 minutes to 9 minutes resulted in a savings of 10% for the unit described in "Bigger is not better" HE May/June 1995.

Because of the inefficiencies associated with the start up of the air conditioner, under most conditions, a smaller air conditioner will produce the same amount of cooling with lower energy consumption.

Bigger is not better.

An air conditioner sized to ACCA Manuals J and S is big enough. Industry specialists who design and sell air conditioners have long used Manual J as a standard method for determining the amount of cooling needed to deliver thermal comfort to single family residences. The procedure is used to calculate room-by-room loads for duct design purposes and whole house loads for equipment selection. It was jointly developed by the Air Conditioning Contractors of America (ACCA) and the Air-Conditioning and Refrigeration Institute (ARI) and it is based on a number of sources including the ASHRAE Handbook of Fundamentals.

Despite the widespread use of this procedure, many contractors have been reluctant to accept the ability of Manual J to deliver adequate cooling under design conditions. One reason for this reluctance has been the lack of information about how actual cooling loads compare to Manual J estimates. While many who have used Manual J extensively have long suspected it has an over sizing margin, field studies had not been performed to verify this anecdotal evidence.

New data show that Manual J overestimates the sensible cooling load in hot dry climates. It is likely that the same is true of the sensible load in hot moist climates. Proctor Engineering Group, Electric Power Research Institute, Nevada Power, and Arizona Public Service monitored air conditioning systems installed in new homes in Phoenix, Arizona and Las Vegas Nevada. By testing the actual cooling capacity required to maintain comfort under severe conditions, these tests have yielded the first measurements that confirm and quantify the overestimation present in Manual J.

The studies showed that even when faced with an extraordinarily hot summer when almost 200 hours exceeded design conditions (design conditions are exceeded only 73 hours in a typical summer), the actual sensible cooling loads of the houses were less than Manual J estimates.

At the most intensively monitored sites in the studies, the data acquisition equipment recorded air flow, temperature drop and moisture removed from the conditioned air. The research team calculated the actual capacity delivered by the air conditioner for every air conditioner cycle.

The systems were monitored from July 30 through September 25, 1995. Occupants were free to adjust their thermostat settings to any value, but most kept a constant thermostat setting. Most of the systems monitored were typical installations (including leaky ducts that increase the cooling load that the equipment needed to deliver).

One typical house illustrates the overestimation contained in Manual J. System 26 had an 11.6% return leak and a 6% supply leak Figure 2 displays the hourly sensible cooling load against the outdoor temperature.

Outdoor temperatures at this house ranged as high as 116¡F (according to ASHRAE Fundamentals the mean extreme temperature for Phoenix is 112.8¡F.) Even though this time period was extra ordinarily hot, the sensible load requirements for all but 3 hours (0.2%) of the 1316 monitored hours the load was less than Manual J estimated cooling load. Manual J over predicted the design load for this house by almost 50%.

These data illustrate that there was no need to oversize the air conditioner beyond the Manual J cooling load because Manual J already overestimates that load.

In fact the air conditioner installed in this house had a design sensible capacity 24% larger than Manual J and that excess capacity was not useful. Because of the over sizing however, the homeowners paid approximately $330 in additional first costs and they will pay additional unnecessary operating costs every summer month for the life of the system.

Using Your Foot for Target Practice

We know designers who determine the system air flow based on floor area (this oversize’s the air conditioner in energy efficient homes), and then try to squeeze down the size of the duct system so that it can be installed in the house. They explain that they can’t use a higher insulation level on the ducts because there is no room, and, when faced with poor performance, increase the size of the air conditioner. If the goal is comfort or efficiency, they are shooting themselves in the foot.

Summary

It is not uncommon for poor cooling performance to be attributed to insufficient equipment size when in fact there is more than enough cooling capacity. Usually, in a residential system, this situation is caused by poor design and installation that: reduce the capacity of the system by incorrect charge, low air flow, and duct leakage, cause noise, drafts, and uneven cooling by using an oversized air conditioner relative to the cooling load and undersized ducts relative to the oversized unit. Most household air conditioning problems will be eliminated when the capacity of the air conditioner is reduced to ACCA Manual J and Manual S standards, an appropriately designed, insulated, and leak-proof distribution system is used, and the system is installed to meet the manufacturers standards These systems will have higher efficiencies because they will run longer cycles and will circulate air as needed a larger percentage of time. Properly designed and installed air conditioners are reliable and will deliver comfort to each room of the house for less cost.

Recommendations Summary List

• Wherever possible reduce the cooling load of the house. Overhangs above east and west windows are particularly effective in reducing cooling load...
• Perform Manual J for all installations and select equipment using Manual S.
• Insure that the system installed never exceeds the capacity of the equipment suggested by Manual S.
• Size duct systems based on Manual D. If in doubt size upwards.
• Determine the grille location and characteristics using Manual T.
• Confirm proper evacuation of the line set and indoor coil with a micron gauge.
• Confirm proper charge using the manufacturers suggested method.
• Confirm proper airflow by test. The flow can be determined from the coil pressure drop when pressure/flow data is available from the coil manufacturer or can be determined with a duct test rig or flow hood.
• Increase the duct insulation above R-4 (at least on long runs in the attic).
• Confirm that the duct leakage is less than 3% of coil air flow for a new system and less than 6% of coil air flow for an existing system

Jules Williams.

MASHRAE

One of the most cost effective ways to obtain home and business Heating.

Jules Williams    Date 2/15/2012.

THE AIRCONDITIONING HEAT PUMP.

An Engineering  marvel that gets very little mention:

It is not common with today’s technologies to find an operation that provides more out- put compared to the energy necessary to initiate a  process. The HVAC heat pump produces  out levels  much higher than the energy needed for its operation.

We all know that heat flows from a warmer to a cooler condition. How is it possible to obtain  enough heat  from outdoors when the  temperature  is 35 degrees Fahrenheit  or lower in order to heat an indoor space?

OPERATION OF A TYPICAL HEAT PUMP: The heat pump uses a refrigeration cycle identical to a conventional air-conditioner. A typical air-conditioner circulates a gas that has a low temperature boiling point through a coil located in the inside of a home or business. The gas being colder than the indoor air picks up heat from the space, and carries the heat to the outside where  air passing through the out -door coil removes heat from the gas. The cycle is repeated until the air reaches a desired temperature.

The Heat pump operates in an identical way except it is designed to heat and cool by reversing the coils automatically. The indoor coil becomes the outdoor coil, in-order to obtain cooling or heating.

WHY WOULD I NEED SUCH A CONTRAPTION: Considering the unpredictable cost for electrical energy, locations with no natural gas has to heat homes and business with electrical heaters. Electric heating is expensive and there are other issues associated with resistance heating.

Last week I operated a test 3 ton heat pump when the outdoor temperature was 40 degrees Fahrenheit  using refrigerant 410A. The discharge air temperature  to the house was 75 degrees Fahrenheit . The unit was consuming 2400 watts to operate, and was delivering 27000 BTU of heat. A typical heat pump can provide 3.29 BTU’s for every watt that it consumes for operation. Compared to using electric heating , the input compared to the output would be 1 to 1. The heat pump  provides more than 2 output  to 1 input. In fact at 17 dry bulb and 15 wet bulb the heat pump performs at 2.6 output compared to input energy. However at 47 dry bulb and 43 wet bulb which is about normal winter for most of Texas, the heat pump operates at 3.6 times its input consumption.

Energy savings using a heat pump compared to using electricity to heat a building is between 2.5 and 3.5 time greater using a heat pump to produce heating. Indoor comfort condition is easier to obtain using a heat pump  when compared to using electric resistance heating.

The heat pump operates for more hours than a conventional condenser when the condenser is sized and installed correctly.

The life expectancy of the heat pump may be less than the condenser; however considering the cost savings associated with operating a heart pump compared to resistance electrical heating the heat pump should be considered for  its economic operation.

My recommendation to home and business owners  is to seriously consider replacing condensers with heat pumps when access to natural gas is not possible. The cost for operating the heat pump will be 2.5 to 3.5 times lower with the heat pump  when compared to electric heating.