What’s a Ductulator?

A ductulator is a design tool that helps designers quickly size HVAC ducts without resorting to a calculator. Originally, duct sizing what based off either tables or charts. Over time as a need to improve productivity a ductulator was invented and is currently in wide use.

A ductulator is composed of four(4) sections: the air volume, velocity, rectangular dimensions, and round duct sections:

In addition, most ductulators also have both a metric and imperial side. The thing to note is that the placement of the  sections is different between the two sides and after regular use, most people are able to determine which units that they are working in.

A typical process to use the ductulator is to use the following process:

  1. Determine the amount of air you are moving, in either CFM or L/S
  2. Decide on the driver for your selection – either pressure drop usually given in in per 100ft or Pa or velocity(m/s or fpm)
    • There is a relationship between velocity/pressure drop and your duct size and energy use
    • Generally the higher the pressure drop, the smaller the duct size, but the higher the energy use.
    • Most designers design to 0.8″/100ft for small volumes and for high volumes, maintain the velocity between 1,800 fpm and 4,000 fpm.
  3. Once any combination of the two variables mentioned above is set, all other readings can be made.
  4. The round duct diameter or the rectangular ducts can now be read.

I hope the quick introduction to the ductulator allows you to get a high level view on how to use it. In other posts, I will get into more details on other intricacies on how to use this tool properly.

On the smartphone, there are many apps that offer the ability to use a ductulator on the go. One of them is Ductulator – Duct Sizer

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