# heating & cooling distribution

## An Easy Retrofit for Return Air From Bedrooms

Posted by on 2017-10-17

Your bedroom really doesn't aspire to be a balloon. Yet, because of the way your heating and air conditioning system was installed, it may be acting like one. At least to an extent. It doesn't expand the way a balloon…

## The Contractor’s Fear of Third-Party HVAC Design

Posted by on 2017-09-28

What if a builder refused to build from plans drawn by an architect? What if a tile installer refused to implement designs handed to them and instead did their own thing? What if an HVAC contractor told a potential client…

## The Joy of Flex

Posted by on 2017-08-08

One week ago I spoke at the Westford Symposium on Building Science. You may know it better as Building Science Summer Camp, since that's what everyone calls it. I wrote up a little summary of the whole conference last week…

## Duct Design 5 — Sizing the Ducts

Posted by on 2017-06-09

To this point in our little series on duct design, we've been calculating intermediate quantitites: available static pressure, total effective length, and friction rate. Today we use all that to find out how big the ducts need to be. We're…

## UL and Intertek Partner With Homebuilders in Energy Rating Program

Posted by on 2017-06-08

In case you didn't see the announcement out of Florida, two big well-known names have entered the market for home energy ratings and energy code compliance. Underwriters Laboratories (UL) and Intertek are working with the Florida Home Builders Association (FHBA)…

## Duct Design 4 — Calculating Friction Rate

Posted by on 2017-06-01

Today's installment in the duct design series is a simple one. It's just a straightforward calculation that gives us the design friction rate from the two quantities I discussed in my last two articles. In part 2, I told you…

## Duct Design 3 — Total Effective Length

Posted by on 2017-05-30

Today we move another step down the road of duct design. I started the series with a look at the basic physics of air moving through ducts. The short version is that friction and turbulence in ducts results in pressure…

## Duct Design 2 — Available Static Pressure

Posted by on 2017-05-26

In part 1 of this duct design series, I discussed the basic physics of moving air in ducts. Now we're going to take that and use it to figure out how to make all the parts work together properly. First…

## The Basic Principles of Duct Design, Part 1

Posted by on 2017-05-25

When it comes to heating and cooling homes, forced air distribution is king. Yeah, my Canadian friend Robert Bean of Healthy Heating pushes radiant for both heating and cooling, and my Texas friend Kristof Irwin drank that koolaid and installed…