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FBI Investigates R-22 Substitute Air Conditioner Refrigerants

 
R-22 air conditioner refrigerant

And the battle over air conditioner refrigerants continues. The US EPA just issued another warning, "cautioning homeowners, manufacturers of propane-based refrigerants, home improvement contractors and air conditioning technicians of the safety hazards related to the use of propane in existing motor vehicle and home air conditioning systems." Now the FBI has entered the battle, too.

A Line in the Sand — The Dew Point Duct Duel

 
crawl space vented duct condensation drop

A line in the sand has some significance for Texas, the state where I was born. Colonel William Travis used his sword to draw such a line in the waning days of the Battle of the Alamo. As General Santa Anna had the Texans completely surrounded and asked for their surrender, Colonel Travis asked for all those who would join him in fighting to the death to cross the line and stand with him. As you can see below, homes in hot, humid climates sometimes draw a line in the sand, too.

The Sucking and the Blowing — A Lesson in Duct Leakage

 
disconnected duct unbalanced supply leakage

Duct leakage is a big deal. It's one of the top three energy wasters in most homes (air leakage and cable TV set-top boxes being the other two). Researchers at Lawrence Berkeley National Lab found that duct systems leak on average about 10% of the supply air they move and 12% of the return air (download pdf). In far more homes than you might suspect, the main culprit is a disconnected duct, as shown below, but a typical duct system has a lot of other leaks, too. But another problem occurs with the duct leakage to cause even more wasted energy.

Is the Aros Smart Window Air Conditioner Worth the Hype?

 
window air conditioner

When it comes to air conditioning, there are a lot of bad products and bad ideas out there. Here are a few: You can buy a cover for your condenser that could kill your compressor. Some people don't think the outdoor unit really needs to go outdoors. (They're wrong!) And then there's the strange notion that attaching a kraken to your air conditioner is a good way to distribute the air. Today, though, I'm going to look at a product that's not terrible.

Fermi Problems, Blower Doors, and the Compressibility of Air

 
Enrico Fermi estimate question problem

Enrico Fermi was famous for many things, as you might expect of one of the smartest physicists of the 20th century. Quantum theory,  statistical mechanics, and nuclear physics were his primary subjects, but what I appreciate most about him was what are called Fermi Problems. He had an amazing ability to come up with estimates for questions for which he had little or no real data.

How Is a Blower Door Like a Hydraulic Jack? Pascal Knows!

 
Blaise Pascal

Remember the first time you ran a blower door? OK, maybe that's not the best way to get where I'm going because most first-timers turn the pressure up like they're practicing tai chi on Jupiter. After you've done a few tests, though, you learn to crank it up to 50 Pascals of pressure difference in just a few seconds. And that's where you may have discovered the mystery that Blaise Pascal solved nearly 4 centuries ago when he invented the hydraulic press.

How to Determine the Size of Your Central Air Conditioner

 
air conditioner size outdoor unit model number tons

Do you know what size your air conditioner is? In the world of building science, you'll hear a lot of talk about why oversized air conditioners are a bad idea. Why? Briefly, they don't dehumidify as well, short-cycling wears them out quicker, and your home will probably be less comfortable if the air conditioner is too big. But to know if your AC is oversized, first you have to know what size it is.

Beware These 3 Expensive Ventilation System Ripoffs

 
wave ventilation system crawl space model

How much does an exhaust fan cost? Search online and you can find lots of them that move 200 cubic feet per minute (cfm) for $100 to $150. But, if you put one in a semi-attractive (emphasis on the "semi") package, create some fancy marketing materials, and target people who don't know much building science, you can charge $1200 to $1700 for that same fan. At least that seems to be the business plan for these three companies.

Why Is This Obsolete Supply-Only Ventilation Method Still Used?

 
ventilation duct outdoor air return plenum

The small duct in the photo below is supposed to bring in outdoor air for ventilation in this new home.  It's a simple method that consists of a duct running from an outdoor wall cap to the return plenum of the HVAC system. A decade ago, it was commonly recommended as the easiest and least expensive way to ventilate a home in a humid climate. When I worked at Southface, however, we made the transition away from it for some very good reasons.

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Our First Hybrid HERS Rater Training - How Did We Do?

 
home energy hers rater training class cantilever floor

We just completed our first combined online and in-person home energy rater training class. I've been wanting to do this for a while now because I've suspected that our attempt to buck the industry preference for a 5-day class by doing ours in 8 days was keeping our registration numbers low. At the request of one of the students who signed up for our just-completed class, I made the leap. Wanna know how we did?

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