46 posts, read 182,329 times 3,191 posts, read 6,854,645 times well since hubby is in the HVAC biz and sitting right here, I'll try to pass on what he is saying... 2 AC systems in a 2 story home is used to provide the same heat & cooling temperatures on both levels. ( warm air rises, therefore more cooling may be needed there If you had one system without zoning, the upstairs will often be warmer than down. Some companies put in a zoning system to monitor each level ,with one AC system, to help maintain the same temperature throughout the whole house. 2 AC systems on a 1 story may be needed if the house is large or the length of the house is very long, or depending on the layout /locations of certain rooms. The largest residential AC system is 5 ton. There are some one story homes that need more 5 tons of cooling. To determine what size unit is needed, a qualified HVAC contractor will perform a manual J load calculation. hope that helps you some

684 posts, read 1,642,638 times Originally Posted by workingwifeandmomac unit miami This is just supposition, but what if you wanted two different temperatures in different areas of the house, or for an addition to the house? ac unit fan blades not spinningYou would need two units in that example, wouldn't you?new hvac cost home 8,535 posts, read 12,566,730 times crazyma stole my thunder..... it is VERY important that the HVAC contractor perform the ACCA Manual J calculations to determine the heating / cooling loads of the house..... that way, the system(s) can be sized properly, giving you the best efficiency for the space and your buck. 385 posts, read 935,462 times 16,275 posts, read 44,896,608 times Originally Posted by latetotheparty

You are VERY correct in restating this!! There is no eye balling it, there is no ton per every so many sq feet 'rule'. Every house is different!! ( and there are 'contractors' out there that have no idea what a manual J is scary thought ain't it) 4,010 posts, read 7,401,586 timesENERGY STAR Version 3 Certification Training for HERS Raters Course Details and Registration (Registration Form is at the very bottom of the page.) This course will provide the training required for a Certified HERS Rater to verify homes under the ENERGY STAR program. The course includes the exam which must be passed to achieve this certification. Successful completion of this course will earn the student 18 RESNET CEU's.
Most ENERGY STAR training programs use a checklist by checklist, item by item approach. We found that method leaves a lot to be desired when you try to apply it in the real world. The “Thermal Enclosure System Rater Checklist” if completed from top to bottom requires you to traverse the same path up to six (6) times - we counted 538 total steps!

The ARN optimized training method instead teaches you what to verify inspection by inspection rather than checklist by checklist. When you look at a window, you are prepared to verify everything needed for that window at one time. This reduces the number of steps to 138 and this is just for one of four (4) checklists which must be completed for ENERGY STAR. Save the steps for the gym. When you are working, every step impacts your profits. Where you choose to get your training can make a significant difference in the amount of time spent on-site and at your computer. ENERGY STAR Program Requirements This module will provide an overview of the ENERGY STAR Program requirements for all participants, the Builder, the Rater and the HVAC contractor. Included is an overview of ENERGY STAR certification paths, the target HERS Index, the Benchmark Home Size and Size Adjustment Factor, and trade-off limitations. Course Introduction: ENERGY STAR Version 3 ENERGY STAR V3: Course Materials

ENERGY STAR v3: Introduction ENERGY STAR v3: Introduction and Basics Quiz ENERGY STAR v3: Prescriptive or Performance ENERGY STAR v3: Builder's Choice - Prescriptive or Performance Path Quiz ENERGY STAR v3: The Prescriptive Path ENERGY STAR v3: The Prescriptive Path Quiz ENERGY STAR v3: The Performance Path ENERGY STAR v3: The Performance Path Quiz ENERGY STAR Checklist Package and Partner Verification What are these checklists that ENERGY STAR Certification Requires? Where are they found? How does a Rater know which ones to use? Who on the project team needs to be trained or credentialed as qualified to work on an ENERGY STAR project? What credentialing responsibility does the Builder and HVAC Contractor have? Those questions and more will be answered in this module. ENERGY STAR v3 Checklists: Course Materials ENERGY STAR v3: Checklists ENERGY STAR v3: Checklists and Partner Verification Quiz Third party verification is a major component of ENERGY STAR qualified homes.

This module will take you to the field and teach you what to look for when verifying for the ENERGY STAR program. You will work through several site visits and understand how what you see in the field translates to what you record on your checklists. ENERGY STAR v3: Introduction to Verification Inspections ENERGY STAR v3 Inspections: Course Materials ENERGY STAR v3: Pre-Slab Inspection ENERGY STAR v3: Foundation and Roof Inspection ENERGY STAR v3: Pre-Drywall Inspection Introduction ENERGY STAR v3: Pre-Drywall Inspection of Walls ENERGY STAR v3: Pre-Drywall Inspection of Fenestrations ENERGY STAR v3: Pre-Drywall Inspection of Moisture Management ENERGY STAR v3: Pre-Drywall Verification of HVAC Design ENERGY STAR v3: Pre-Drywall Inspection of HVAC Systems ENERGY STAR v3: Pre-Drywall Inspection - Other Considerations ENERGY STAR v3: Construction Complete Inspection Partnering with ENERGY STAR This module includes information about ENERGY STAR Partnership benefits and how ENERGY STAR helps you grow your business.