I know there are a lot of possible factors that go into determining the size of the air-conditioning system a house needs. Is there a standard way of calculating what is needed, or do A/C companies each devise their own method? Is there a guide somewhere to aid a home-owner in figuring it out? You'll want to check out the ENERGY STAR Air Conditioning Sizing Calculator. To roughly calculate the required BTU output of an air conditioner you will need to total up the results of six calculations. Square footage of area to be cooled. (Length x Width) x 337 Area of south facing windows. (Height x Width) x 871 Area of north facing windows. (Height x Width) x 166 Heat produced by people (# of people x 400) Heat produced by lights (Total wattage of all lights x 4.25) Total heat produced by appliances (Total wattage of all appliances x 3.15) Add all of these numbers up to determine the BTU output required of the air conditioner (Source).

You could also use a site like this Air Conditioner Sizing Worksheet to make the calculations.cost to replace air handling unit It probably depends on climate as much as it does the square footage of your house but the general rule is one ton for every 400-500 square feet of house. how much does a ac window unit costThere are a ton of other factors like vaulted ceilings and if you have dual pane windows and if you have 2x6 construction and therefor more insulation in the walls but for the most part none of that is going to factor into the unit. discount auto repair tempe azIt goes more like this: Contractor: How big is your house? You: about 1900 square feet Contractor: I see the house is older You: Yeah, it was built in the 50s

Contractor: 5 ton it is! Contractor: I see the house is newer You: Yeah, it was built in the 90s I think you need to look at the Discover Ways for Air Conditioner Sizing in order to get an idea of the size of the AC unit. Two out of three suggested methods include Manual J which is exact science - but not many contractors want to do it for free. There's a ton of variables: A good HVAC pro will be able to do the proper calculations for you.Browse other questions tagged hvac air-conditioning or ask your own question. 1. How many rooms do you want to cool?Skip to main menu Skip to main content You are hereSBA.gov » Starting & Managing » Managing a Business » Running a Business » Energy Efficiency » Calculate Energy Savings » Energy Saving Calculators from ENERGY STAR Energy Saving Calculators from ENERGY STARCorrectly Sizing a Capacitor I don't know how many times a technician has said that they installed a part based on what was on their service truck. 

I have heard of technicians wasting money over-sizing contactors, cutting down air filters, and even using controlled substances to clear condensate drains!  Of course, these scenarios all get the job done, but I would argue the many reasons why not to do these.  The one thing that gets to me is when a technician doesn't verify they are installing the correct size dual run capacitor.  Believe it or not, there is a simple method to figuring the correct size capacitor, without waiting on hold for the distributor's guru.  Of course, you could use a multimeter that reads microfarads (uf), but this will only tell you if the existing capacitor is weak - not the correct size! Testing Volts / Amps With the condensing unit operating under a load, you will need to measure the total volts between the HERM and COMMON terminals on the run capacitor (i.e. 345 VAC).  Next, measure the amperage on the wire leading from HERM to START on the Compressor (i.e. 4 amps). Use the equation below to verify the size of the capacitor.

The resulting microfarad (uf) should match the size of the installed capacitor. An over or under-sized capacitor will cause an imbalance in the magnetic field of the motor.  This hesitation when operating will cause noisy operation, an increase in power consumption, a drop in motor performance and eventually overheating or overloading motors like compressors.  The run capacitor should have the exact microfarad (uf) that the motor is rated for.  Capacitors rated above 70uf are considered Start Capacitors and are generally removed from the circuit electrically during operation.  This is where the rule of +/- 10% of the rating came from, for Start Capacitors ONLY!  The voltage rating should be no less than the listed amount for the motor, for central heat pumps and air-conditioners this is usually a minimum of 370VAC.  Most new condensing units are specified for 440VAC capacitors, and are more durable during fluctuations in power supply.  I have seen some universal type dual run capacitors rated for as much as 700VAC, as this voltage rating does not impact uf performance. 

The changes in uf will impact amperage draw and reflect on kilowatt hour usage though. When completing your early season maintenance this year for your customers, do them a service by testing capacitors and verifying their size.  You could just increase your service ticket total and save some all important power.  You may even prevent a call-back during the next heat wave! < Previous Post Next Post > Room Dimensions (in ft.) Area of Windows (in sq. ft.) Is your floorBasement or Ground Floor First or Higher Floor Are there any floor(s) above yours Yes Number of people occupying the area Predator generator buying guide Portable generators are ideal for providing power to lights and home appliances during power outages, enabling power tool usage at remote job locations, and powering up electronics during camping trips and tailgating parties. Two of the main considerations when selecting a portable generator are the running watts, also known as Output Watts, and starting watts, or Maximum Output Watts.

Output Watts is the power needed to run a given device at normal functionality. Many devises need more power to start up (Maximum Output Watts) and then require less power (Rated Watts) to run continually. For example, a refrigerator requires 2200 starting wattage with a 700 running wattage, so you would need a generator with at least 2200 watt maximum output. We've provided you with a simple worksheet at the bottom of this page that will help you determine how much power you need based on your respective application. If you're using a generator for multiple applications, select the generator that will accommodate the application with the greatest power demands. Once you identify your power needs, match them up with the output specifications under each product description to find the right Chicago Electric or Predator generator — it's that easy! 212cc, 4000 Watts Max/3200 Watts Rated Portable Generator - 420cc, 6500 Watts Max/5500 Watts Rated Portable Generator -

420cc, 8750 Watts Max/7000 Watts Rated Portable Generator - 23.2 x 18.7 x 19.29 27.1 x 25.8 x 22.4 Wheel Kit for Predator Generators Available in Stores! Emergencies, job site use, garden, heating and cooling Wattage Worksheet Reference Guide Running Watts (Rated Watts) are continuous watts needed to keep your item running. Starting Watts (Maximum Watts) refers to the maximum wattage the generator can produce. It usually takes 2 to 3 seconds to start motor-driven products such as a circular saw or a refrigerator. Motor-driven items require additional starting watts. If your appliance or tool doesn’t have the running watts you can estimate by using the following: AMPS X VOLTS = WATTS Click the items below to calculate wattage Electric Range - 6” element Electric Range - 8” element Sump Pump - 1/3 Horse Power Sump Pump - 1/2 Horse Power Toaster - 2 slice Well Pump - 1/2 HP Toaster - 4 slice Portable Heater - 30,000 BTU

Portable Heater - 85,000 BTU Clothes Dryer - Gas Portable Heater - 140,000 BTU Clothes Dryer - Electric Vacuum Cleaner - Standard Furnace Fan gas or fuel oil 1/8 HP Vacuum Cleaner - Deluxe Furnace Fan gas or fuel oil 1/4 HP Furnace Fan gas or fuel oil 1/2 HP Central AC - 20,000 BTU Central AC - 32,000 BTU Central AC - 40,000 BTU Microwave Oven - 625 Watts Black & White TV Air Compressor 1/2 HP Electric Line Trimmer Heavy Duty 12 Air Compressor 1 1/2 HP Drum Mixer 55 gall - 1/4 HP Bench Grinder 6 inches High Pressure Washer 5/8 HP Bench Grinder 8 inches High Pressure Washer 1 HP Bench Grinder 10 inches Electric Line Trimmer standard 9 Band Saw, 14 inches Split Phase 1/8 HP Circular Saw Heavy Duty - 6 1/2 inches Split Phase 1/4 HP Circular Saw Heavy Duty - 8 1/4 inches Split Phase 1/2 HP Electric Chain Saw 12 Inches - 1 1/2 HP Capacitor Start Induction Run: