Duct Testing in the San Francisco Bay Area

As a HERS rater I travel all over the San Francisco Bay Area and test HVAC systems for code compliance.

What I so often see is systems that just barely scrape past the code requirements or are over and need more work to get them to pass the duct test. Recently I learned about a club of HVAC contractors who actually pass the test so well that the test equipment can’t even read how much air is leaking from their systems. That is because there is almost no air leaking from their ducts, fittings and air handler units. How do they get these contractors get their systems to be so air-tight?

To begin, there are only eight HVAC  contractors in California who are building HVAC duct systems so tight as to earn their way to the “4 Ring Club”. Ring 4 refers to the Energy Conservatory duct leakage test system’s #4 ring which is the smallest. It is the one used on the smallest and most leak-free systems. These installers build ducts that even Ring 4 can’t register. These elite contractors can be found at http://ring4club.com/. They are all Home Performance contractors, a title that discerns them from standard HVAC contractors. They install high performance comfort systems. They are the hot rodders of the HVAC world.

What do they do differently? One, they see the house as a system and create larger work scopes than standard HVAC contractors. They start at the shell of the building and do a home energy retrofit rather than just  “changing out the box” or replacing an old furnace or air conditioner with a new, usually same sized unit. These techs do it by the book. They do a manual J heat load calculation, manual D duct design and a Manual T register design to dial in performance to every part of their HVAC system.

When it comes to installations, what they do differently is to actually commission their work. This means that after the work is done, and even during installation, they test every performance aspect of their work.

Regarding ducts, they paint every piece of metal duct connections and any part of metal to metal with a thick application of air duct mastic. Secondly, they properly clamp the flex ducts onto the sheet metal. Here, properly means that instead of hand tightening the zip-ties over the connection, they use a tensioning tool such as http://www.homedepot.com/p/Malco-Manual-Cut-Off-Tensioning-Tool-with-Grips-TY4GTS/100161814.  A recent Home Energy Magazine article notes that the difference between hand tensioning and using a tensioning tool is significant air loss. Lessen: use a tensioner for tight ducts.

New, Free Load Calculation Software

Load calculations are the way to dial in the capacity of your heating and cooling systems so that they work at peak efficiency while delivering comfort. They are also required by California’s 2013 Energy Code, Title 24, Part 6.

While software like Right-J from Wrightsoft cost $499, there is a new free option to do load calcs, Cool Calc. The software is web based and uses google maps and other on-line data to capture information about the house. The software won the Gold Award in the 2015 Dealer Design Awards.

Many contractors still use crude and inaccurate rules of thumb to size their systems while putting themselves into potential legal liability. One of our clients was threatened with legal action after he used an old rule of thumb for sizing. The system he designed and installed did not perform to manufacturer specifications. The building owner had some testing done and threatened a lawsuit unless the system was done to specs. That contractor now uses Wrightsoft software and creates state-of-the-art installations.

Opting for free and proven software can be a smart way to go. It is infinitely better than guessing like so many do. The Air Conditioner Contractors of America have been around for over 40 years. You can trust them when it comes to the methodology of sizing air conditioning systems. Now, with the 2013 California Energy code enforced around the state, this is a good time to switch from guessing to calculating air conditioner system sizing. Check out Cool Calc at Next Generation HVAC Sizing and Selection tools | Cool Calc

George Matthews

Building Energy Compliance Testing

San Francisco to Silicon Valley

www.bect.us

What homeowners need to know about the new California Energy code before hiring an HVAC contractor

Before buying a new system or contracting for the repair of an existing air conditioner/furnace and ventilation system from a licensed California HVAC contractor, there are a few important questions to ask. Consumer protection agencies usually suggest interviewing at least 3 contractors before making a purchasing decision.  A new HVAC system will effect your energy costs for decades.

First, ask which method the contractor uses to calculate the size of the air conditioner and furnace. There are four code-approved methods. These use volume, insulation levels, glass type and size, air tightness and orientation of the shell of the house to calculate the correct unit size and “room by room” air flow.  If the contractor uses a simplistic square footage “rule of thumb” from the 1970s, ask the next contractor on your list. The ACCA, the Air Conditioner Contractors of America, have published paper calculation forms for a long time, probably since before your contractor was born.

“Please tell me about your duct design process....”  If you are met with a blank stare or surprise, ask the next contractor on your list. These days, software, such as Wrightsoft, is commonly used to guarantee correct system sizing and CFM of air-flow to each room in your home.

Ask them about total airflow. “How many cubic feet of air will this system move?” New California A/C systems are code-required to move 350 cubic feet of air per ton of cooling (12,000 BTUs). Top notch contractors are delivering up to 550 CFM per ton, providing more comfort and efficiency for our dry climate where we don’t need to remove much, if any, humidity.

Ask about the duct leakage rate they will be providing to you. Code requires 6% or less leakage, existing systems must have less than 15% leakage. Experienced contractors routinely hit the 3% level while hot-rod-high-efficiency contractors sometimes beat 1% leakage.

How much will my heating and cooling bills be after you install a new system? “There is no way to tell…” is not the response that you are looking for. More advanced contractors will be able to model your house and new HVAC system in a software program such as EnergyPro and be able to give you a good idea what your future costs will be.

Ask what type of motor will be in the new equipment. Air conditioners depend on the fan motor of the furnace, to move system air. The two types of motors are standard and ECM, electronically commutated motors. Standard motors are either on or off. ECM units are more efficient and often able to vary their speed according to the need for cooling.

One of the required tests performed by California HERS Raters is called Fan/Watt Draw. The test measures how many Watts (power) of electricity it takes to move one (1) cubic foot of air. A system must use less than 0.58 watt per cubic foot of airflow. The difference between passing and failing the test could be an ECM motor and a well-designed duct system.

For extra credit, here is a good question to pose. “This high performance, properly calculated and designed, energy efficient heating and cooling system, guaranteed to pass California’s strict energy code and provide us decades of energy savings... costs more than I have lying around in my checking account at the moment… Is there an affordable financing instrument that requires a ‘less than stellar’ credit rating? Is there be some sort of low interest, government loan for this type of thing?”

Your in-the-know HVAC contractor should be able to point you to a PACE, Property Assessed Clean Energy loan provider. PACE loans require no credit check as long as you own your own home with no taxes owed or liens against the property. Our application process took about 5 minutes before approval!

California has at least 10 PACE energy independence loan providers as of this writing. California First in Sacramento is one such provider. The Sonoma County Energy Independence program is the type of service that every California county should proudly aspire to. To learn more about PACE loans check out http://www.pacenow.org/resources/all-programs/

If your contractor can answer the above questions to your satisfaction, your next question might be, “When can you start?”.

www.bect.us

Building Energy Compliance Testing

HERS Duct and A/C testing for Compliance with the 2013 California energy code

San Francisco to Silicon Valley