Part 1 of: The "1-2 Punch" to HVAC "Not Understoods"

HVAC Delivery System Losses -

This is the Air Pressures, Duct System, the Boots, the Registers, Equipment Cabinets, Air Balancing, Temperature rise and drop parameters, etc. 


This is a greatly overlooked and not understood part of a system, even by most HVAC Journeymen and contractors. How do we come to this conclusion? Ask yourself how many HVAC guys actually proposed to modify and improve duct and delivery systems when there is a need for HVAC improvements.


If they really understood the delivery systems they would be making improvements - because the benefits are undeniable. Energy losses through delivery system issues can be up to 60% of the energy used in an HVAC system. Yes that is right up to 60% of system energy losses. The Comfort improvements from modifications are undeniable as well. 


If one could reduce system losses through delivery systems from 60% to lets say only 20% that would represent a considerable improvement. Mostly this will show up to the building owner as huge comfort improvements. Reduced noise, less dust, no distracting temperature variances, etc are constantly what I hear from my customers when they call me back to rave. 


There is a technology to HVAC delivery systems, and it is not rocket science. It has its foundation in published engineering data that has been around for decades.


  • Where did we go wrong? There are big disconnects between installer comprehension of duct engineering, and a big disconnect between engineers and actual installed conditions. How does engineering work when an installer has to wrap a flex duct around framing, when the engineer could not have predicted or calculated the additional turns, etc. That is just an example. There are many, many other issues related to these disconnects.
  •  How do we go right? Train the installers - they need to know just enough, and that is about all. I am currently doing research on how to get just enough training through to the installers. Wish me luck.


This is the entire basis for the Super Efficient HVAC Series that I am developing.


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Comment by Bob Blanchette on January 14, 2012 at 7:58pm

Bringing ductwork into the conditioned space would go a LONG way to making things right. New houses could be designed with ductwork sizes specked into the building plan instead of just having the HVAC contractor wing it.

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