Air-conditioning Manufacturing Companies can do many important economic value-added advantages computerized design engineering additions to increase the Market Value of their Heating and Air-Conditioning Equipment to Consumers    - with Darrell Udelhoven

If I were an air-conditioning (HVAC) manufacturer, I would consider creating high service and economic utility value-added comparative-advantage computerized additions to the equipment I manufactured. These value-added comparative-advantage additions would be used to get a sales (advertising) advantage over the competition. This could easily have a huge impact on HVAC contractor and consumer equipment preference.

Consumers want to know that the equipment they buy, and have installed, is performing at optimal capacity and efficiency. Therefore, it behooves companies to make it easy for equipment owner's and the contractor techs' to check the running capacity and efficiency performance of the equipment.

A small low cost kilowatt meter with computerized recording of run-time and length of run-cycles of the condensing unit would tell the owner and tech a lot about the the units operating efficiency.

It would be easy for a manufacturer to put the needed information in the owner's manual and using stickers' on the inside of the condensers' access panel, also on the indoor air-handlers' for use by both the service techs and the owners. This information should also be put on the Internet for equipment that was sold out to 15 years ago, which would add value to that manufacturers' service oriented reputation. Which manufacturer would you want to buy you HVAC equipment from?

The paramount impediment to full capacity efficient performance is the lack of a uniform optimal heat-load through the indoor evaporator coil. After the tech has checked for proper ductwork sizing and for any leaks in the supply and return duct system which must be sealed with approved mastic, duct insulation should be checked. The second thing to check is the External Static Pressure (ESP) of the duct system before any other checks and adequate remedies must be performed. Ask the occupants if there is uniform heating and cooling to the various rooms; if there are no dampers in the ducts trhey should be installed so that airflow can be properly balanced to eachy room.

Proper Sizing of Residential Heating & Air Conditioning Ductwork Systems

Optimizing the Evaporator BTU/hr Heat Input  Important

Do your own figuring based on this formula. Motor BTU/hr additive = Watts X's PF x's 3.413 for Btu/Watts additive added to rated BTUH, divided by condenser fan CFM X's 1.08 =  condenser Temp-Split.
Get the Motor Power Factors (PF) of the compressor and fan motor from the manufacturers. (A 0.90 factor could be close.)

To get the gross BTUH Heatload the Evaporator (DX) Coil is absorbing (which includes both latent, sensible heat) (These are ARI Formulas)
First, determine the Gross Rated BTUH the condenser is ejecting. 
Condenser’s Gross Btuh = Condenser’s rated CFM X’s Temp Split X’s 1.08

The chart split listed below is at Condenser Design conditions: Indoor Return Air 80-F dry bulb 67-F Wet Bulb or 50% Relative Humidity as you go up to 99% RH the condenser split could increase by up to 6-F; down as much as 4-F at a low humidity of 55-F Wet Bulb.
The chart split listed below is at Condenser Design conditions: Indoor Return Air 80-F dry bulb 67-F Wet Bulb or 50% Relative Humidity as you go up to 99% RH the condenser split could increase by up to 6-F; down as much as 4-F at a low humidity of 55-F Wet Bulb.
Do your own figuring based on this formula. Motor BTU/hr additive = Watts X's PF x's 3.413 for Btu/Watts additive added to rated BTUH, divided by condenser fan CFM X's 1.08 =  condenser Temp-Split. Get the Motor "Power Factors" (PF) of the compressor and fan motor from the manufacturers. Some Splits rounded.
CONDENSER TEMP-SPLITS - Comfortmaker® 12-SEER units - used 0.90 Motor Power Factor
1.5 T  +17,500  +17-20Split  Cond. CFM 1400 WATTS 1591x.90=1432x3.413=4,887+17500=22,389/1400=15.9x1.08=17.3
2-Ton  24,000  23-F Temp-S  Cond. CFM 1400 WATTS 2067x.90=1860x3.413=6349+24000=30349/1400=21.7x1.08=23.4
2.5-T  30,000  21-F Temp-S  Cond. CFM 2000 WATTS 2778x.90= 2500=8533+30000=38533/19.2x1.08=20.8
3-Ton  35,600  14.8-F T-Sp  Cond. CFM 2800 WATTS 3096x.90= 2786+35600=38386/2800=13.7x1.08=14.8
3.5 T  42,500  17.6-F T-Sp  Cond. CFM 2800 WATTS 3578x.90=3220+42500=45720/2800=16.3x1.08=17.6
4-Ton  48,500  19.5-F Split Cond. CFM 3400 WATTS 4174x.90=3756.6x3.413=12821+48500=61321/3400=18x1.08=19.5
5-Ton  59,000  23-F Temp-S  Cond. CFM 3400 WATTS 5043x.90=4539x3.413=15,490+59000=74490/3400=21.9

CONDENSER TEMP-SPLITS - My Brother's Heil 12-SEER Condensing Unit 
1.5-Ton - Rated at 17,500-BTUH,  Condenser fan CFM 1400 (Total Cond. Watts 1591 X's power Factors0.90 X's=  1432  X's * 3.413 =  4887-BTUH Motor Heat additive +17,500= MotorPower "Rated Gross Heat Ejection" is 22,387-BTUH / 1400= 15.99-F x 1.08= 17.27 Temp Rise Cond/Split. His condenser only gets a 10 to 12 temp rise split, the evaporator appears to be under heat-loaded or, an unbalanced heatload on the DX coil's circuitry. 

Click for Graph

Page 618, Refrigeration & Air-Conditioning (ARI) Second Edition, C 1987
Those lower SEER units had higher condenser splits than 12-SEER and higher units.
Sorry, I defiled the graph, 90-db outdoor, 80-db indoors with 67 wet bulb/50% RH represents the condenser splits shown above.

The graph should use 78-F indoor dry bulb (DB) and show the correlative Relative Humidity (RH) to the Wet Bulb (WB)-F readings. Equipment owners could then use an accurate Relative Humidity indicator so they could perform the temperature split diagnosis. Graphs would be specific to the equipment. Condenser CFM should be shown on the metal equipment specification tag and in all spec literature and in the home owners manual.

Typical matched units from major manufacturers have Sensible Heat Ratios (SHR) in the 68% to 80% range (or 32% to 20% Latent) when it is 95-F outside and 75-F with 50% relative humidity inside. Proper mixing of the air and proper distribution to individual rooms is critical for comfort.

All air-handler equipment should have capped ports for taking static pressures with information on how to do it along with a line graph or other information of the blower performance at various static pressures.
My scan of doctored Thermopride OL 11

These are added value features that can be used in all advertising and marketing, providing your company with a distinct value advantage to all potential customers.

All of the above information should be easily accessed on the Internet for the convenience of techs and equipment owners.

Air-conditioning contractors could make up sticker graphs showing how to check the capacity of the A/C they bought from you. It's a "Value Added Feature," you could promote to even your potential customers, they will appreciate you doing that for them.

Better Cooperation by manufacturers' toward, distributors, HVAC/R Contractors, Techs, and all consumers of their equipment would make performance evaluation simple and easy to perform.

The motor vehicle techs have the dynamometer to evaluate the delivered horsepower of the motor under various loads and conditions.

HVAC/R techs and consumers have NO easy way provided to evaluate the varying load BTU/hr performance of an air conditioner evaporator and condenser design combination.

Let us say it is getting the design optimal-load on the evaporator and condenser however, the run-time is much too long for the A/C unit's design and the design cooling heat-load, --where do we look next?

We look at the supply-air (SA) and (RA) return air-ducting system for design and installation problems.

Many Return Air systems set the furnace on top of a RA chamber that is not sealed off from hot attic air —which overloads the cooling coil. This is also very dangerous, as the RA suction will put a negative pressure on the combustion-air venting and could easily result in carbon monoxide poisoning and death!

In most homes there is NO Return Air ducting to the various rooms. When the system pressurizes a bedroom, this positive pressure forces the conditioned air out through any opening in the room to the outdoors. Building science research states that for every cubic foot of air forced out of a building, a cubic foot of air infiltration must be drawn in from outside to replace it.

Therefore, when air is forced out of a room under pressure an equal amount of air is drawn into the main body of the home to replace the air forced-out. Depending on the number of doors that are closed, the rate at which hot or cold outside air enters the home goes up by from say, 300% to 900%. In turn, utility bills go up, comfort goes down, and health problems may ensue.

In a four-bedroom, home it could be drawing in almost 1,000-(CFM) cubic feet of outdoor air per minute with all of the doors closed! "With a high outside humidity and/or temperature difference, the air-conditioner may never catch up to the added heat-load."

To allow for cooling mode Return Air, the "upper panel of a door can be removed and an upward louvered wooden or metal grille can be installed." Alternatively, make a grilled opening of the proper size through the wall near the ceiling.

The Case for (TXV/TEV) Thermostatic Expansion Valve Refrigerant Controls & Higher SEER Ratings

TXV's give a colder coil than (Flow-rator) pistons under the same conditions and get colder faster.  I have a data logger that has two external temperature probes. I put one before the coil and one after the coil.  I start the data logger, then turn the AC on.  The TXV gets 18 to 22 degrees across the coil in 5 minutes and 80% of that in 1 to 1.5 minutes.  The piston gets
16 to 18 degrees in 10 minutes and 80% of THAT in 5 minutes.  Under part load conditions the TXV will dehumidify better.  Most systems run most of the time under part load conditions.  Guess what?  I am going to install TXV's most of the time, just to cover my back side. - Stretch | 4/28/05 (NG)

Gurgling sounds at TEV:
Low evaporator heat-loads lead to reduced liquid line mass and increased evaporator mass could be due to airflow problems. Eliminate low evaporator heat-loads before looking into adjusting the refrigerant charge. -- Gurgling and pulsation noises at the expansion device can also be caused by low evaporator circuit heat-loads, low charge, and/or non-condensable and moisture in the system. Unbalanced airflow through the various distributor circuits of the evaporator coil will cause the TEV to close down refrigerant flow starving the coil. Piston-flow-rators will make it impossible to properly charge the system and cooling will be greatly compromised unless you eliminate the cause!
Lennox and other companies now have some of the computerized engineering I was talking about:

"The XC21 has a "Systems Operation Monitor" - Similar to the diagnostics system used in automobiles, this monitor continually measures system performance, helping technicians solve problems faster and more accurately. It can even communicate with select thermostats to provide you with a "Check System" type indicator when service is needed for added peace of mind. "  - Lennox Statement

"Customizable: Can be paired with a SignatureStat™ control combines the functions of a humidistat and thermostat into a single device.

Simple menu-driven programming helps you control your energy costs and comfort. "  - Lennox Statement

The XC21 Combines with a Variable Speed furnace blower.
On every Rheem condenser cover it lists "non-condensable and or moisture" as causes for a gurgling or pulsating noise at the expansion device. The entire evaporator circuits may not become active for various reasons; the entire coil must become fully active.
Air Temperature Drop Through Evaporator Coil (1987 Period)
Indoor temperature and humidity load variations graph.
Refrigeration & Air-Conditioning (ARI) Second Edition,
Page 624, © 1987

Darrell's Refrigeration Heating and Air Conditioning - Retired
If you want to discuss
the AC test checks you can do to know what your AC system is doing, I'm in the Lancaster, WI - Beetown section..

Darrell's Refrigeration Heating and Air Conditioning -
Retired - Federal Refrigerant Licensed 

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Posted: 04/20/05; Last updated: 09/11/06