HVAC DECISION MAKING How to choose an HVAC Contractor Package or Split? How about Mini Split? How to do Sizing? Sizing the ducts? Duct placement? Seal or Replace? Customizing for Climate? Where to place the system? Filtration, how important? Diminishing Returns on Efficiency? Energy Source, gas, elect, propane? 1
THE HVAC CONTRACTOR This is the most important player on the Energy part of your team. Know this: 1. Most contractors of all types are susceptible to a “We’ve always done it this way” tendency. 2. HVAC Contractors continuing education should have included whole house integration. They should understand insulation and infiltration and their effect on HVAC load.
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THE HVAC CONTRACTOR 3. They really do need to do Manual J and Manual D calculations. J is for the heat load of the house D is for the ductwork WrightSoft is a good program for Load Calcs. 4. If they propose “rule of thumb” (such as 500 feet per ton) calculations they are not the right contractor for an EnergyWise project.
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THE HVAC CONTRACTOR 5. In California, Training by and membership in California Building Performance Contractors Association (CBPCA) is a good indicator. 6. BBI Certification is also good.
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PACKAGE OR SPLIT Package Units are Cheaper Less Efficient Easy to keep combustion outside the building envelope Split Systems are More Expensive Customizeable Can be more efficient Easier to do super filtering 5
HOW EFFICIENT? The least expensive (US) unit is 13 SEER cooling and 80% efficiency heating. Available in Package or Split. Package Units get slightly more efficient. Split Systems can get a lot more efficient (for a lot more money) Reason is they can be customized to the project and the climate. Package Units are “one size must fit the whole country� Houston and Fresno are totally different and use air conditioning for different reasons. (water removal vs cooling)
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HOW EFFICIENT? The homeowner wanting the best with no budget constraints will probably choose a customized split system. As Energy Wise House Flippers who must sell the finished product at a profit, we usually choose the 13 SEER 80% Package Unit. Least expensive. Combustion all outside. Then we put the saved money into the improved envelope and insulation Other benefits are lower maintenance cost and ease of service by any HVAC tech.
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HOW ABOUT MINI SPLITS? This is the technology used by the entire rest of the planet besides USA. Why? Americans have bought the idea that they need a lot of forced air blowing into every room. Typically Mini Splits have had only one or a few indoor units. New Developments allow small short duct systems to aid in distribution to satisfy Americans.
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HOW ABOUT MINI SPLITS? Benefits of Mini Splits 1. High efficiency up to 21 SEER and more. Due to Inverter = DC technology. This variable speed motor is used on both the compressor and the fan. American manufacturers have only figured out how to use ECM motors on the fan. Rumor has it that ECM motors on compressors will be the next big thing from US manufacturers. Dont expect it to be cheap. 9
HOW ABOUT MINI SPLITS? 2. No duct loss. Because there are no ducts. 3. Original Cost is less 4. Electric Heat Pump heating eliminates combustion altogether. One recent Price comparison for complete new installation 13 SEER Package on roof $6500 High Efficiency Split System $8000 MiniSplit with minimal ducts $5500
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HOW TO DO SIZING The right answer is with Manual J for sizing the equipment to the heat load of the house. And Manual D for sizing the ducts correctly. The rule of thumb of 500 square feet per ton was approximately right in 1965 when we had single metal windows, no wall insulation, and maybe R11 in the ceiling.
What’s wrong with this picture?
Surprisingly builders are still using 500 ft per ton resulting in MASSIVE OVERSIZING 11
HOW TO DO SIZING WrightSoft is a good software for load calcs and duct calcs. It can be done by hand. Manual J & D available at ACCA. Can be reduced to an excel spreadsheet. You dont have to do this. You just need to know the HVAC contractor is doing it. (correctly) 12
SIZING THE DUCTS This is the reason that we never try to do “duct seal� and believe that duct seal programs are a waste of time and money. Even if you seal a system well, It is still incorrectly sized and dirty in need of cleaning and worn out (in the case of flex) and in the wrong places. It is better to tear the old stuff out and start over. Use Manual D 13
PLACING THE DUCTS As short as possible. Minimize the ducts in the severe conditions of the Attic Under freezing to over 140 degrees Use R8 for sure (code is R6, contractors will tell you its adequate) Then cover it up with more insulation. Ducts should run to the closest point in a room.
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WHAT ABOUT THE RETURN? You almost cannot go too large. A larger, freer breathing return will mean less static pressure = more efficiency Example: Standard for a 2 ton unit in our area is 14 inch duct for the return. Some use 12. We use 18 plus another 12 to a second return in the master bedroom.
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FILTERS AND SUPERFILTERS The standard one inch Rock Stoppers are designed to protect equipment, not lungs. If you want to protect your lungs, a thicker and better filter is required. This will increase static pressure and decrease efficiency. Increase filtration wisely and ensure that occupants service the filters.
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CUSTOMIZING FOR CLIMATE Package Units are not customizeable One size fits all and we work around it. For Split systems in our climate: 1. Make the indoor coil bigger 2. Blow more air rather than less 425-450 cfm per ton 3. Condenser a little smaller Only an experienced HVAC Contractor should make these decisions
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WHERE TO PLACE IT Package units go on the roof, centrally located on the back side. They are best mounted on a curb with the air blowing down thru the curb. Split Systems typically have the condenser outside on a slab, but it can be on the roof. The air handler, furnace can be in a closet, in the attic, basement, garage or in a “doghouse� outside. Concern is the possible CO or fire. 18
WHERE TO PLACE IT We really like to get the possible products of combustion outside the envelope. That makes a package unit on the roof a good idea. Also building a dog house outside the envelope for the furnace accomplishes the same goal. Propane has even more concerns as it is heavier than air. It will build up in a basement or even an attic with potentially bad results.
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BASICS OF MINI SPLITS Here are a few pages of the Fujitsu Mini Split brochure. Full info at Fujitsugeneral.com Johnstone Supply is one of the distributors of this equipment.
For over 35 years, Fujitsu has been making the hottest places cool and the coolest places more comfortable.
Mini-Split Air Conditioners and Heat Pumps
More info will be coming on these calls as GreenEarthEquities builds one of these systems 20
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The Allowable Combinations make the Fujitsu Mini Split adaptable to most residential applications (even in the US) if you have a creative HVAC Contractor who is willing to go “outside the box� This is the combination we will be using on our 1350 sq ft home 23
HVAC DECISION MAKING Questions? Who’s made an offer this week? Who’s got a problem property? Are you using Cyberhomes.com? Have you interviewed a realtor? Have you found a good one? Are they quick to run CMA’s for you? Good deals are still out there. I just made an offer. Full price and I will hope for a haircut..... What a country... 24