Questions - Answers - Tips !
Question
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Click here
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Customer cost
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Hours per year (example)
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ARI, EER, SEER ?
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Design temperature
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Unit price list
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Melt 1 ton of ice ?
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I want a larger AC ?
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Duct insulation ?
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Air is carried & returned via ducts ?
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Grille sizing
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Central is a 24 hr operation ?
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Humidity ?
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Fan set On or Auto ?
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Booster fans in duct ?
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Refrigeration lines ?
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Drawing / Drafting programs ?
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Customer temperature check ?
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Operation cost ?
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Energy Annual usage
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Warranty Vs Maintenance ?
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Thermostat location ?
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Ventilators for attic ?
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Attic insulation ?
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Heat Pump Balance Chart ?
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Annual Maintenance & Tips
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Choosing unit Brands
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Two units or one
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Temperature conversion
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Heat Transfer Terminology K-C-U's
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TIPS
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Heat Pump vs Furnace?
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Sweating (water spots or dripping)
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Down payment
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Radon
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Air leakage test
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I believe it was back in the 60's there were no ratings for air conditioners . The only ratings, (BTU's divided by electrical that runs the unit), were the capacities in BTU's , (unit output), & unfortunately some sales people would do things that would favor their story & equipment such as NOT calculating all the electrical that is required to run the unit (two fan motors and the compressor).
When EER / SEER was figured on the compressor only it would appear to be a higher rating than that with the two fan motors included.
Lennox, G.E (now Trane/American Standard), and Carrier, (they being the only three that I remember), said there should be a rating with certain rules for this rating and tested by ARI. (Air Conditioning Refrigeration Institute). Thus the EER, (Energy Efficiency Ratio), was developed as a 1 hour rating. All air conditioning equipment be it split or self contained units were calculated in a "cal-i-rim-e-ter" room supplied by some of the main factories but done by engineer's from ARI. This room would simulate various weather conditions along with each units criteria such as so many feet of duct, refrigerant lines, and other items that were to be the same for each unit tested. These engineers would evaluate the unit's operation at these different conditions and come out with an EER or now a SEER rating for equipment.
After the EER rating Lennox, G.E., and Carrier said there should be a "Seasonal" projection to represent a full year & would be more accurate. Thus the SEER, (Seasonal Energy Efficiency Ratio), was developed & that's what we go by today. ARI, (Air Conditioning Refrigeration Institute), publishes a book with ratings. The difference between the EER & SEER was approximately .5 (1/2) efficiency rating.
Units that are tested will be in the ARI Directory which ac dealers & many utilites have.
A test done by a large utility company of 144 new air conditioning units installed discovered an efficiency drop of 1 SEER, in other words if the ARI book rating was a 12 SEER when installed in the home it produced an 11 SEER. The reason for this reduction could have been the actual length of the duct, refrigerant lines, the way the unit was installed, and other installation factors. That is some of the reasons of a properly designed and installed system. You want to get the most for your buck, not the least. You will probably never know but your utilites will be higher than a properly installed system and that continues on after the installation. Unfortunately there are those that will NOT have any regard to a properly installed system which reasons are many but some are, cheapness and they don't have the knowledge they should acquire, so choose as wisely as you can.
The ARI, (Air Conditioning Refrigeration Institute site is
click here
is funded by the manufactures and each system has a cost associated with it's rating performance. A challenge can be made of any rating results but it has to be paid for by the losing manufacturer.
1 ton of ice:
It takes heat to melt ice. Ice melts at 32° F. The heat it takes to convert 1 lb of ice into 1 lb of water is 144 Btu's. It is called the latent heat of fusion and that 144 Btu's is the amount of cooling it will do. A ton of ice weighs 2000 lbs. When it melts it does 288,000 Btu's of cooling. 2000 x 144 = 288,000 Btu's. A ton of refrigeration is 288,000 Btu's of cooling over a period of 24 hours. So 288,000 divided by 24 = 12,000 Btu's.
If my calculation is a 3 ton then I want a 4 ton:
Air conditioning is the absence of heat, thus you are left with cooling. It's not like filling a bucket full of cooling. It's removal of the heat in the home. That's one of the reasons air circulation is important. Any air, (room), not getting to the furnace, blower, will not have satisfactory results in that area. Over sizing can bring moisture problems, (certainly in humid areas). Excessive moisture can be blamed partly on oversizing and operating the fan on continous "blow".
Manual J will allow 15% of the sensible load to be added to the total calculated Btu's.
A central system is designed for a 24 hour operation.
Cooling equipment size should be based on the calculated sensible and the calculated latent, (moisture), cooling loads. Procedure "D" of Manual J says that when the cooling equipment is operating at the outdoor design temperature it's sensible load and it's latent capacity must be equal to or greater than the calculated latent load.
Air conditioning, (cooling only), equipment should be selected to keep oversizing to a minimum.
Load calculations are NOT done by the maximum temperature outside that's why you should see what the design temperature is for your area.
Duct insulation:
Ducts have liner or exterior wrapping. Usually there in 1" to 2" thickness and rated in "R" values such as R4 or R6. When wrapping, (external insulation), is used, two things come to mind. DO NOT pull the insulation too tight because you will loose the "R" value and make sure all seams are sealed to air tightness. These can cause moisture problems as well as loss of capacity. A formula for determining "R" value for your duct is: The surrounding air temperature of the duct minus the inside air temperature in the duct and divide that result by 15.
Example: (150° - 62°)/ 15 = 5.8, "R" = 6
SweatingSweating or condensation (dripping of water) is caused by outside air coming in contact with a duct or grille that is not sufficiently insulated and / or the air in the specific area is not completely circulated through the air handler meaning a supply as well as a return needs to take place.
The more humid the air the closer is a dew point (sweating). That's one of the things the air conditioner does when it removes the heat from the air, a dew point may be reached causing the condensate to drain the water to the outside.
A glass of ice tea is a good example where cold comes in contact with hot and creates a dew point (sweating)
Ducts carry & return air to the unit for conditioning:
Duct sizing is very important & can be in ratio with the amount of air delivered. That is one of the reasons why a load calculation is done room by room. That tells you the amount of air that should be delivered. [ There is approximately 30 Btu's per CFM for cooling.]
Example: If you have a room that calculated to 3000 Btu's then you would need 100 cfm to that room. Of course that also depends on how long the run is, the effective length of the duct but for a lot of homes under 100 effective feet this works.
If you are not expert in duct design then I suggest you don't try it & find someone & have them fully guarantee it. We guaranteed the duct system for as long as you lived in the home.
About grille sizing
All grilles supply wall, floor, ceiling, and return will have a manufacturers spec sheet so they can be selected by their noise level, effective free area, volume of air and throw or pattern of that air.
Below is an example of a spec sheet for a particular side wall supply grille.
Below is a sample of a return grille spec sheet:
Dealers do not need to refer to a spec sheet each and every time for their selection or size. After experience for a particular manufacturer & their grille they can come up with various "rules of thumbs" that are pretty accurate based on the information received. Be advised though those "rule of thumbs" are based with certain grilles in mind & do not encompass all grilles, supply or return.
We try to stay around the 500 ft per minute neck velocity, supply or return. When that is exceeded then noise level starts to increase and the amount of air could be reduced.
We also try to chose the cfm that is needed for the room and the grille can deliver, ( and return ), without creating a hurricane and a lot of noise (drafts). When the amount of air throws further that the chart allows then a draft could occur.
Sizing the grille for the proper amount of air, it's distance in throwing that amount of air, and the noise level of that grille is very important. Unfortunately a cheaper grille, smaller grille and it's noise level from this cheaper grille could affect your comfort.
Have grilles selected correctly and have them guaranteed in your contract.
When someone tries to select or size a supply or return grille without the proper information then they very well may get into trouble.
Central ac is a 24 hour operation:
A central system is to be turned on & left on during the summer months. It's size or capacity has been determined for a 24 hour operation, (to help control humidity). If a unit has been turned off then heat will get back in the carpet, furniture, etc. Just the air in your home doesn't take long but all the other heat that is in the surroundings takes awhile. If your gone all day then you may want to raise the temperature to 80°-82°. Better yet is a programmable thermostat. See the installing ac contractor about this.
Fan set to Auto or Continuous,(on):
The thermostat setting for "on" is continuous air circulation even when the thermostat is set to off. The "Auto" setting is the fan will come on or off with the compressor only.
Usually a fan running all the time not only cost you for the continuous operation of the fan but is generally from a room/s getting too warm under the "Auto" setting (for air conditioning). Set on the continuous setting the air is in constant circulation and the thermostat reads or senses the temperature quicker. This constant movement of air results in the compressor going on & off more frequently but doesn't run as long as the "Auto",(automatic), position.
The constant fan has 2 downsides, 1. is the cost of operation of that fan & 2. the moisture is not removed as much as the "Auto" position. Moisture in the home could affect high humidity areas greatly. The thermostat only determines the temperature at it's location.
The first suggestion is to pull the drapes, blinds, etc and operate the unit with the Auto setting. If this doesn't do the trick you may need to go to the "ON" setting. Normally if a unit has been sized properly, the duct system has been sized correctly, the home has received the correct "conservation measure's", then you shouldn't have this type of situation.
A clean filter helps in good air circulation. One site for electrostatic permanent filters is
click here
and also go to "links & Sites" (see the menu.)
Air duct Booster fans:
Booster fans are undesirable, noisy, inefficient, and are a poor fix for a greater underlying problem.
If you have perceived the need for a booster you should remedy the problem not simply put a Band-Aid on it. It's a poor solution and you will probably never be happy. When they quit they act as a restriction and most don't last.
Refrigerant lines:
Refrigerant lines need to be sized correctly. Those lines mainly do two functions. They circulate the refrigerant so many times per hour, (each pound of refrigerant asorbs Btu's from the evaporator coil), & that refrigerant keeps the compressor cool. If the lines are too small then capacity can be reduced & compressors can run hotter than they should. Sizing can be affected by the elbows, T's, fittings, connections, & of course the distance. The ac contractor has the manufactures recommendations, manuals and books that will suggest the proper size.
You will have insulation on the larger pipe & that's so you won't have sweating or possible too high of a "superheat". Superheat is primarily so the refrigerant asborbs enough heat to turn to "gas" before it goes into the compressor. If some liquid gets into the compressor it can be like a BB and damage the valves. Proper size of refrigerant Lines are very important & precaution should be taken. Otherwise compressors can be burned out.
Note: Copper lines are NOT to come in contact with certain materials. Usually PVC sleeves are used to alleviate this problem.
Warranty Vs Maintenance: (see also annual maintenance this page)
Seems to be much confusion in this area. Warranties cover parts & labor for a specified time. So make sure the warranty is written.
Maintenance usually pertains to draining, (condensate), & maybe filters, (see if this is included). If the drain, (condensate), overflows & a serviceman is called out there can be a charge for this. NO coverage under the warranty. Dirty filters are also a source of many things wrong with the system which can be a charge to the customer. Oh yes don't let me forget those electrical breakers that may trip in a storm. Those also are not covered with a warranty & I would hate to see you charged for a service call when all the service tech did was flip on a breaker.
A maintenance contract is suggested. For homes you can get by with seasonal checks. The service tech should spell out what they checked & some of their readings and findings. If you take care of your system & it has been installed properly then it should last for quite awhile.
Customer temperature checks:
One way for a customer to see it their air conditioning may be cooling is to take a temperature check. Take a temperature of the return air, (preferably in the duct air stream), and another at a supply grille. The difference should be 14° - 18°. Now there are other things that come into play but this is for the customer to do a quick check of the system.
What that basically does is it gets the temperature of the entering air at the return then the air is carried to the inside coil sometimes called the evaporator. Air crossing the evaporator coil does or doesn't do it's work then on to the supply grille via the air ducts. The supply grille air temperature is when the air has gone across the evap coil. The difference is the amount of work or heat removal by this coil.
For temp differences below 14 deg the air conditioner has to RUN longer to do the comfort job and that could adversely affect your utility bill. Low temp differences may not cool your place. Too high of a temperature difference could be a restriction of air across the evaporator coil.
For heating you will have a temperature rise and it will depend on the type of heating for that temp rise. Heat pumps are usually in the 90's and gas or oil is usually in excess of 100 degrees.
Customer cost / bid:
Consist of two areas. Installation cost & what is referred to as life cycle cost.
Installation cost is comprised of all material used, equipment & related, all labor used to install & complete the job, warranties, permits, taxes, then overhead markup & any profit markup. Many overheads amount to 15% to 25% of all added cost & profit usally is 10% to 20%. So contractors don't have the mark up as one might think. New construction mark up is even less. That's one of the reasons a company might not be around next year to take care of you.
Equipment and material used could be the cheaper type, sometimes the overhead & profit is not what it should be, all of those things added will give the cost or estimate to the customer. Smaller grilles, ducts, less quality can & will be a lot of the difference of prices. Items that maybe smaller or less quality can affect the next cost of "Life cycle".
Life Cycle cost consist of annual operation cost for "heating & cooling", maintenance on your system, (such as condensate drains, freon gas charge, motor & compressor amps, & certainly other items that are not included in the warranty and service that may be needed over the next 5 or 10 years.
To properly judge what your cost may be takes a lot of evaluation on your part.
What is furnished & installed should be listed on a contract. a sample contract
Operating cost :
(Usually are not done by the customer but they should be aware of how it is done and the operating cost should be done & told to the customer.)
Degree Days or Bin Weather Data ?
Operation cost, energy consumption, return on investment, & pay back can be figured for a location.
There is a form for this and it is predicated on temp, unit Btu output at that temp, load required at that temp, unit kWh, hours per year at that temp, and percent running time. That gives one the kWh or fuel consumed at that temp. You have to supply the cost of fuel in your area. When temp hours, (bin method) are totaled then one can get the complete operating cost and even fuel consumption for the year. Then you can see if a pay back for the selected unit is feasible. Also a lot depends on how long the customer plans to stay in the home, is it a rental, etc.
Unfortunately there are those salespeople that make claims based on the wrong criteria such as so much savings per month. This will give the home owner false data and they may expect pay backs not only quicker than they really are but their decision may be based on this erroneous information. Potential customers should know what the Heating / Cooling system is going to cost them per year for operation as well as the fuel consumption.
Degree Days, (DD):
When the outside temperature falls below 65°, heat will be required to maintain the inside temperature.
Example: Heating degree days for Montgomery, ALA is 2,250. You can also go to this site for Heating degree days for 250 cities
click here
Bin Weather Data:
Is considered as the most accurate of the methods.
Also you can see by adjusting the "Thermostat" you can raise or lower the fuel consumption.
The hours per year at shown temperatures come from the dealers Manual "J ".
Example: Montgomery, ALA-Outside Degrees °F (There are hours per year for your location)
Heating
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None
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Cooling
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10°
to
15°
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15
to
20
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20
to
25
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25
to
30
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30
to
35
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35
to
40
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40
to
45
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45
to
50
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50
to
55
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55
to
60
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60
to
65
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65
to
70
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70
to
75
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75
to
80
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80
to
85
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85
to
90
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90
to
95
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95
to
100
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100
to
105
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3hrs
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5hrs
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17
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63
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159
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329
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455
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567
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663
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708
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799
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965
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1235
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1121
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751
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500
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332
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89
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7hrs
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Heating below 35 degrees is 247 hours per year, above 35 degrees 3,521 hours a year. So less than 1% of the winter is below 35 degrees.
A heatpump will generally do the job down to 35 degrees outside , ( again the heatpump balance chart will show this ),then another form of fuel is needed to maintain your comfort.
Your operation cost will also be affected by the thermostat setting and what your fuel cost below 35 degrees maybe.
These hours a year come from the "Weather Bureau's" statistic over a 10 year period.
Cooling can be 3,421 hours per year, you can see how cold you want the air can affect your electrical & fuel bill.
Later I plan to show the energy consumption for various heating & cooling units. Maybe your dealer already has this information. He / She should as that helps in your selection of heating and cooling equipment. What your total investment would be vs your payback.
Thermostat setting can affect your operation cost or for that matter when equipment is not performing the way it should or unit sizing is not correct those things can affect running time which also affects utility consumption. So it's very important to install the system correctly and get the maximum output at the least fuel input to run the system.
When a load calculation is done to determine the amount of BTU's required for cooling and heating then the Design temperatures are used (example: Montgomery, Ala shown below). ..
You will notice that for cooling temperatures of 95° outside & 75° inside are used. For heating 25° outside and 72° inside are used. What that means is when it is 95° outside you can get inside your home down to 75° or heating when it is 25° outside you can get inside your home up to 72°. When guarantees of temperatures or what equipment can & will do then "design temperatures" are spelled out on your contract.
When conservation or additions are added to the home after your installation and Load Calculation, they change the homes required BTU's capacity for cooling & heating. The unit could now be sized improperly. When an air conditioning unit becomes to oversized, (BTU capacity), then humidity problems can occur. When the units capacity is too small then your comfort can be sacrificed.
The below example of a Design Temperatures .
Example: Atlanta, Ga. Outside hours per year (10 year average Weather report)
Heating
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None
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Cooling
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10°
to
15°
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15
to
20
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20
to
25
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25
to
30
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30
to
35
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35
to
40
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40
to
45
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45
to
50
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50
to
55
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55
to
60
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60
to
65
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65
to
70
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70
to
75
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75
to
80
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80
to
85
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85
to
90
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90
to
95
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95
to
100
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100
to
105
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6hrs
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14hrs
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20
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82
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255
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455
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627
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651
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700
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817
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908
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978
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1188
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880
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620
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361
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172
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23
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2hrs
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Example of Design temperatures (shown below) for the area (Atlanta) 
Hours of unit operation per year (cost to Heat & Cool) for a given area will be shown below.
Bin method cooling form:
Some of the forms can be saved or printed if they can you will see the following when you right click on form
( to save or print, right click form , "print picture" or "save picture as" then name it & save to the directory
of your choice located on your harddrive ).
Later I will calculate on these forms so you can see an actual sample.
Bin method for heating:
It is reccommended that an air conditioning & heating contractor take the time to make the annual average usage for each
ton of air conditioning to show the customer what the projected cost of operation, (heating & cooling), maybe
and what equipment they may suggest based on these calculations.
A contractor needs to only do this once for each unit then they can put them in protective covers to show the customer.
The cost of operation, annual energy needed to maintain the comfort level, and the maintenance and service say for a 10 year period.
The annual energy calculation is also in ACCA's Manual "J".
The cost each month to operate a system will be a part of your payback, utility bills, and overall cost not just the installation cost.
Look at those items that will present a cost to you.
1. Equipment & Initial installation cost, 2. cost to operate your system, and 3. maintenance & service.
These methods are used in the annual cost of operating a system, (heating & air conditioning), as well as any pay back.
Usually the air conditioning contractor can calculate this for you.
Thermostats sense the temperature where & only where they are located. So that room not by the thermostat is not regulated or the temperature is not sensed by the stat & turned on or off. When two floors & two separate ac systems are installed make sure that if one is off, the unconditioned air does not affect the "ON" ac & thermostat. That's a good reason thermostats are generally located by the return air.
Ventilators for the attic come in powered to non powered. The powered, (electrical), ventilators use power to extract heat, (power) from the attic and usually there is no gain at all. The best type are the turbo or goose neck roof jacks on the roof, those that are non electrical. The heat for summer rises through those jacks and can cross ventilate your attic. The down fall is for the winter months those roof jacks should be covered. I would check with the local distributor and see what they recommend for your region.
Always have insulation in your attic. The insulation in your attic, when sufficient, is for the "Design Temperature ONLY" NOT for 125 degree plus attics. Be aware of the insulation you have and this fact for the amount of heat will be affected by a hotter / cooler attic. These are not in place of but used with your insulation.
Attic insulation is very important & can affect the winter and summer load calculations as well as your utility bill.
Let's say the summer design outside to inside is 95° to 75°. No insulation would be 21 Btu's per square foot. (A Btu is approximately 1 match.) With insulation - R-19 is 2.5 Btu's per square foot and that insulation is based that the attic will not go over 95°. (See why proper venting should be used.)
"R" values & Btu's could even be more due to your location and the type of construction you have. Can you imagine the size of heater & a/c & the utility bill with no insulation or insufficient insulation over the entire area.
A good site that gives "R" value per 1" thickness, try this
click here
The Heat Pump balance chart is also done with these facts. Below is an example of a Heat Pump balance chart. (For AC people it can be found in the Manual J book).
One takes the Heating load calculation & makes the 1st line by drawing from the residence Heat Load to a 65 degree temperature, ( 65 degrees is always used), from the spec sheet take the Heat Pump data (Btu output) & draw the 2nd line. You can then see where the Heat Pump does it's job to where the two lines cross.
Below that line you need other heat to keep up with the colder temperatures and may very well not use the heat pump at these colder temperatures. Usually other more economical fuels take over then, ( depending on your area ).
.
Heat Pump vs Furnace ?
The Heat Pump above it's temperature on it's balance chart will be very effective, lower cost of operation, and comfortable but ........
One needs to be aware of the rise in air temperature in a furnace and a heat pump.
Especially when replacing a furnace with the heat pump. This should be explained to the home owner before hand.
A furnace may be around 125 degrees in it's air temperature to a room while the heat pump may be 95 degrees. Both are warm or hot and will keep your comfort but the heat pumps air seems to be colder to the hand when a customer checks the feel of the air blowing out of the grille. Comfort will still be there but customers need to be aware of the difference. (Either one needs to be properly installed and especially the heat pump with the balance chart - see "Heat Pump" at the MENU).
Annual maintenance for residential should be at a minimum of twice a year. One as you go into the cooling season and the other as you go into the heating season.
Maintenance is not part of the "Warranty".
Cooling they primarily check the condensate drain & put some drain tablets in the drain pan, check the blower as well as the coils for dirt build up, check the current levels of freon gas in the system which not only can affect your comfort and your utility bill, (consumption), as well. A few other things are checked but always ask the technician what is going to be and what has been checked. It's always a good idea to get those checks in writing or a list.
Heating depends on the type in your home but should also be checked at the start of the heating season. Gas or Oil furnaces have orifices to be checked as well as the heat exchanger.
Officials recommend the following tips to ensure the safe and efficient operation of their natural gas furnace:
Check the color of the flame. The flame should be predominantly blue. While flecks of orange are normal, a predominantly yellow flame indicates a condition that could produce carbon monoxide.
Vacuum and clean regularly around the furnace, particularly around the burner compartment to prevent a build-up of dust and lint.
Never store items in, on or around the appliance that can obstruct airflow.
Most forced-air units have a filter that cleans the air before heating and circulating it throughout the home. The filter should be checked regularly and cleaned, or replaced, if necessary.
When installing a new or cleaned filter, be sure to re-install the front panel door of the furnace properly so it fits snugly. Never operate the furnace without the front-panel door properly in place because doing so may create the risk of carbon monoxide poisoning.
Check to make sure the furnace or appliance is venting properly. Signs of improper venting include soot around the appliance or moisture on the inside of windows when the appliance is on.
Again it's a good idea to get a list of the maintenance items to be checked & were checked.
Remember maintenance is not part of your warranty and will have some cost associated with it but it's well worth keeping your equipment in good operating condition.
A reply to maintenance on the HVAC, air conditioning, news group by one of the good service men. Steve @ Noon-Air Heating and A/C.
"Because it *might* only need a good clean and service plus something like a relay....but on the other hand, it could be time to replace it... without actually being there and troubleshooting the system (after it has been cleaned and serviced) in person, I can't say... while a good technician doing the work on the system would be able to make that determination....and educate the customer about the benifits of yearly maintenance at the same time. It may make the difference in giving the customer time to save up for a really great system or just scraping by with a cheap "spec house special".
I don't know about you, but I want the call in the next year or 3 to come install a really great system -and- all the word of mouth referals from this customer."
Choosing brands or manufactures is important but not the most important thing to look for. Choosing the contractor to install the unit is probably the most important thing to do.
The best unit if not properly installed can be a real nightmare but on the other hand the worst equipment installed properly by a professional contractor can be a blessing with little trouble.
Choosing the contractor can be made easier by his/her approach to the job. Are you involved by their asking questions. A real concern for you comfort. Then a load on your home for unit sizing should be done. Always get a contract that spells out what is going to be done, equipment to be used, what the units annual operating cost for heating & cooling would be, and other factors that should be taken into consideration. Rest assured that the professional will not have any trouble with that ( take a look at the "Sample Contract" location shown on the Menu").
Unit types .... everyone will say what they sell is the best but I would suggest staying with the major brands. My personal choice is Trane/American Standard, Lennox, and Carrier. In that order. I base this on my experiences for 35 years. There will be other dealers that take exception but this is my opinion.
My experiences for over 35 years has been install a unit on every floor. Yes I tried one unit to also do the 2nd floor but had very limited success. I was very successful installing two systems. The customers comfort is at concern here.
The primary reason was two fold, one not enough air got to the 2nd floor and it is always hotter on the 2nd floor, therefore I would always add 1/2 ton of air in unit sizing, (after I did a load calculation). My suggestion is to operate both units during the same time. If one unit is turned off you may not have good results. The turned off AC may circulate hotter air in the turned on AC.
Fahrenheit to Celsius
Thermal conductivity:
K value
The rate of heat transfer through a particular material is a characteristic of that material. Thermal conductivity (k) is defined as the number of heat units (BTU's) that will pass through one square of a uniform material one inch thick in one hour with a one-degree F temperature difference between the two principal surfaces of the material. A mean temperature of 75 degrees is normally included as a condition. A material with a low k value may be considered an insulator.
C value
C value or thermal conductance may be defined as the number of heat units (BTU's) that will pass through one square foot of a building material of actual standard thickness in one hour with a one degree F temperature difference between the two principal surfaces.
R value
R value or thermal resistance is defined as the ability of a material to resist the flow of heat.
U value
The overall heat transfer coefficient
U value is defined as the number of heat units (BTU's) that will pass through one square foot of a combined building section in one hour with a one degree F temperature difference between the two principal surfaces.
Component R values (in series) may be added to obtain a total R value for a particular building section. K values, C values, and U values may not be added together.
HTM value
The heat transfer multiplier is the amount of heat that flows through one square foot of building envelope at a given temperature difference.
HTM = U value X temperature difference
The C-value (C) is a measure of the Thermal Conductance of the material and is the reciprocal of R, or
C is determined only when the Thermal Conductivity (k) of a material is known.
Thermal Conductivity is the measure of the amount heat that will be transmitted through a one inch (1") thick piece of homogenous material, one square foot (1 ft.2) in size, in one (1) hour, when there is a one degree Fahrenheit (1° F) temperature change. The equation for "k" is:
TIPS !* Try drawing a floor plan with 1/8" graph paper. You can place the direction the house faces, input exterior/interior walls, type & square foot of glass, etc. If a second floor is also needed then you should use another graph sheet for that or each floor.
While measuring I wouldn't worry about exact measurements. Just round off and be approximate.
* A home typically generates heat of approximately 8°.
* Use a 50 ft - 100 ft tape when measuring.
* A tool belt that can be strapped on your person and has examples for the customer to see, electrical, copper, drains, armaflex,(pipe insulation), and other items that may be helpful.
* A notebook with pictures for the customer of equipment, (indoor/outdoor), hours per year at various degrees of your area and any other item that you deem necessary. A picture is worth a thousand words.
* Always have a clean and good appearance plus your vehicle to. What the customer sees will probably reflect in workmanship as well.
* Keep your shop clean & organized and use that as a sales tool. Recommend to your customers to visit the shop of who they may do business with.
* The more positives and less negatives you have the better for you & your customer. One of my best selling tools was my competition. They talked about me negatively & ask the customer were they getting a quote from me. (Now they will).
* Treat your customers with honesty & sincerity. Things that are non-important to you are very important to the customer and they generally have a reason to ask the question.
* A drawing / Drafting programs are VDraft or Smart Draw. VDRAFT site is
click here
SMART DRAW site is Smart Draw
* Replacement systems you can have a list of choices for the customer by tonnage (if created in a spread sheet then you can sort as you like). When this list is created in Lotus or Excel then you can sort by SEER, Monthly payment, Price, whatever is best for you and your customers.
You ( the dealer) can show the installed price of some things not included but needed. Such as Outdoor support, indoor plenum, electrical upgrades, & so on.
Home owners can see prices for different types of units, add on's and share in their own selection.
Please don't use prices shown as they are not accurate for today's project.
Not shown is the continuance of sizes etc but you get the idea.
Dealers never have the same tonnage let alone the same units. They always differ in the material and what is to be done. This list is an advantage to you the dealer and the customer.
Down Payments:
I cringe every time I see on the news where someone paid almost all of the money before the job started. What ever the companies reason that should not happen.
The "normal" down payment has been from $0.0 to 25% of the total job. However when the job is completed and approved by the city/county inspector then the balance will be due and should be paid. Any thing that may later go wrong is covered under the warranty and guarantee of the installing company. A company representative will go over the system and make sure you are happy with it. If you are not the issues should be addressed before final payment is made.
In this industry things are becoming to costly and to complex, especially for the homeowner.
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