I'd appreciate comments on how to maximize the energy savings from using a runaround loop coil and energy recovery wheel in series.
I'm modeling a lab HVAC air handler that has an energy wheel and return/exhaust fan at the air handler but where 1/3 to ? of the OA is exhausted elsewhere (a dedicated fume hood exhaust system). The designer is considering an option for additional heat recovery via a runaround loop with glycol coils at the fume hood exhaust and the air handler OA stream. This is in a heating-dominated climate (CZ 6A) and the SAT will be 55F.
- Any thoughts on how to arrange the coils in the OA stream, which will also include a glycol preheat coil and a CHW coil? (Runaround coil -> wheel -> preheat coil -> CHW coil?)
- How to control the system? (Activate and modulate the wheel first; activate the runaround loop when OAT drops below the point that wheel can maintain the mixed air temperature?)
- I assume the pumping power for the runaround loop would be higher than the motor power for rotating the wheel.
Thanks!
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
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