Q. I am working on the design of a Dedicated Outdoor Air System ( DOAS ) unit. I am leaning towards using double wheel units (latent and sensible wheels). What is your opinion on this approach vs. using a wraparound heat pipe. Rick… From my viewpoint the dual wheel design is a much less efficient… Read more »
Posts Categorized: Air Handling Units
Project Snapshot: Custom Field Erected AHU for University of Texas
Project Name: University of Texas Tower Air Handling Unit Replacement Location: Austin, Texas Project type, building type: System overhaul, school (college, university) Mechanical Engineer: EEA Consulting Engineers Equipment: Custom Field Erected Air Handling Manufacturer: Air Enterprises (AEI) Project duration: 1.5 years Project completion date: April 30, 2007 Engineering challenges Location and space constraints for the… Read more »
Composite Wheel Technology | A Good Idea
Composite material design has been the hot topic in new construction. We recently visited one of our manufacturers. They shared a new fan wheel design from Ziehl-Abegg. This is a design that will begin to take center stage in the HVAC design industry. Composite Fan wheels are a great idea. These are key advantages… Read more »
5 Reasons to Consider a Composite Air Handling Unit
I cycle quite a bit. I average about 2,000 miles a year. Around the office that hardly counts as two workmates easily double that each year. We ride a lot and we like bicycles. When is the last time you bought a bicycle? Things have changed a lot in 25 years. I have posted a… Read more »
Ask Rick: Prefilters in Front of an Energy Recovery Device?
Ask Rick: We are working on a lab application and considering not using filters on the exhaust side in front of the energy recovery device. I would like to hear the pro’s and con’s on why not to install filters. This will help us in designing future projects. I would think the efficiency would fall… Read more »
Air Handling Unit Refurbishment | A Viable Solution
Problem: Tired, Aging Air Handling Units We look at hundreds of Air Handling Units each year. All types, all sizes and all conditions. Typically we are called in to assess problems or look at replacement options. In some cases units are not in bad condition; they don’t need to be replaced, just refurbished. I… Read more »
Ask Rick: Air Handling Units | Single point power connection?
Q. We are in a disagreement over specification language. In your opinion what does a “Single Point Power Connection” include? Thanks, Boston Engineer. Good Question. This comes up all the time. Depending on the application and circumstances “Single Point Power Connection” is defined in multiple ways. Typically there are assumptions made, often times wrong,… Read more »
Custom Air Handling Units | Coil Selection Guidelines
I have included a collection of notes that we have pulled together over the years that guide us through typical coil selections for custom air handling units. Coils Basics: Header Orientation – Supply low leaving, return high entering Coil Hand – Face the entering air side of the coil to determine its hand connection. With… Read more »
Air Handling Unit Design | A More Efficient Direct Drive Plenum Fan
We are using significantly more and more direct drive fans these days. Annexair, a leader Energy-Efficient Air Handling Systems, standardizes on direct drive fans for all their units. They are more efficient, quieter, require less maintenance and last longer (see – 4Reasons Why we choose Direct Drive Fans). The efficiencies of these fans were a… Read more »
Custom Air Handling Units | Preliminary Design Questions That Are Asked
Every Custom Air Handling Unit starts with a list of design parameters that must be answered. If these items are explored and discussed early on it makes for a significantly better design. Here are the key items that we look for in preliminary Custom Air Handling Unit design. Project Scope: Description of application – what… Read more »