I’ve been seeing lead times for Air Handling Units (AHUs) recently at upwards of 40 weeks. The unpredictability seems like it would make capital planning pretty difficult since you can’t be sure that you can install equipment in the same year that you purchase it. While it would be nice to cut those lead times down, that doesn’t seem likely in the near term. To me, now seems like the ideal time to try to get the factory to install your on-site controls.
COVID and California wildfires have driven home how important it is to have programmable controllers in your AHUs. Factory controls were generally not responsive to the needs of sites that wanted to be able to reduce Outside Air intake when the sky was orange and grey with carcinogenic particulate. Nor were they consistently able to respond to the needs of sites that wanted to operate in a 100% OA intake mode in order to reduce COVID transmission. Having your local controls contractor be able to implement site-specific sequence-of-operation changes is no longer a luxury. It is a necessity.
This change in direction is not without complexity, though. One of the challenges is schedule impact. Generally, the rooftop work for controls starts after your unit is set. Typically, the controls contractor’s work starts after the mechanical and electrical contractors get the unit wired, piped, and set. Trying to do that work in parallel is typically counter-productive to both timelines and cost. Since the automation system is the commissioning agent’s window into the system, this work must be finished before commissioning can start.
However, I have found that many factories are open to installing custom controls components that I ship to the factory ahead of time. I usually ship the parts and controls drawings as a bundle and go over any questions from the factory prior to the factory fabricating anything. When the unit is ready, I visit the site and ensure the operability of all the components prior to shipment. Typically, I also load the programming at this time and perform an initial point-to-point and functional verification. In this way, we have a high degree of confidence that there will be no controls-related delays, and we deconflict the work with the on-site trades. When we are allowed to implement our typical suite of fault-detection and diagnostics, we also can use our automation system to identify faults with work in process, so that we can stay ahead of problems instead of letting the operators find them.