Ask Rick: Pumped Glycol Energy Recovery | What size systems make sense for Konvekta?

I am working on a project where we are considering glycol run around coils for heat recovery. I would like to consider using a Konvekta system.
The building in question is an existing hazardous materials storage building with 24×7 exhaust air requirements. There are 16 separate exhaust fans and a single common make-up air unit. The current plan is to remove the in-line exhaust fans, install the glycol coils within the building at these locations and provide new rooftop exhaust fans. The single, common, make-up air unit is also to be replaced with a new gas-fired unit with the final energy recovery coil located upstream of the gas section. Preliminary make-up air unit size is 8,620 CFM,  so this is not a huge system.

Will it make sense to use Konvekta on this project?

A.  Unfortunately the Konvekta systems haven't been making sense for smaller projects. The total supply air flows typically need to be greater than 20,000 CFM to make them payback in any sort of reasonable time. The more efficient Konvekta coils are more expensive than traditional coils. The pumping skid and controls are the heart of the system and add significant cost to smaller systems. The cost differential for pumping skid and controls could be nearly the same price for an 8,000 CFM system as a 50,000 CFM system. That makes the smaller systems really expensive.

Also, in this case, the greater number of exhaust coils would add a significant cost. 

For most systems we are now seeing paybacks on Konvekta equipment of about 2 years over traditional pumped glycol systems.  In many applications there is little cost difference between the two systems.  In nearly all cases, we do a cost analysis to make sure the project makes sense.

Rudolf Zaengerle, Ph.D.
President, Konvekta USA Inc.
5 Independence Way, 3d Floor #95
Princeton, NJ 08540
Phone: 724 462 8207