Installation challenges for HVAC systems
By Charles “Chip” Greene
Nearly every facility needs heating and air-conditioning systems. However, not every facility is designed with what is necessary to install these systems. Thus, the fun begins when the project is awarded, and it is left up to the construction team to make the systems all go in and work.
There are numerous circumstances that create these challenges. Some are related to the type of structure, some to cost, some to expectations vs. reality. Below are some examples:
• Wood structures — My company does primarily heavier commercial projects — schools, medical and institutional facilities. While most of the facilities are either structural steel or concrete structures, economies of scale sometimes dictate that these facilities be wood frame construction. In my opinion, HVAC ductwork and wood construction can be incompatible.
I recently did a two-story school that was wood frame construction. When I got the truss shop drawings there was a 12-inch clearance between the ceiling and the trusses, and I had 20 inches deep duct in the ceiling space. I was offered the alternative of putting it into the joist space. In order to do this I needed a minimum of 48 inches between the joists. The design was for them to be 24 inches apart, so that was not an option. We wound up adding 24 inches to the height of the second floor to allow the duct to fit. Basically, wood structures cannot carry the load that steel structures can without deeper, closer together joists leaving very little room for mechanical systems.
• Low-cost HVAC systems (with high expectations) — Controlling temperature with chill water on an air unit is much easier and efficient versus controlling DX refrigeration. The same with zone control; you can do a much better job with VAV boxes with reheat coils to regulate various zones in the building vs. using a bunch of small split systems to try and accomplish the same thing. Both chill water and VAV systems cost more to install but provide lower operating costs and better control for the end user. The problem contractors (and engineers to an extent) run into is the owner wants both; he wants an HVAC system that is the least expensive to install but has expectations for it to perform like a much more sophisticated and costly HVAC system.
• Incomplete documents/scope — We recently were awarded a renovation project where the drawings were incomplete. Equipment was noted to be replaced but no scheduled information regarding size and capacity was listed on the drawings; parts of the system that operated on R-22 were to be replaced with R-410a, but other portions (evaporator coil) were not noted to be replaced. This resulted in change orders before we even started the project. And then it was determined that asbestos was obviously present in the work areas, delaying our ability to start. As a result a project that was supposed to be a summer project is now probably going to be a Christmas break project.
• Lack of coordination — Contract documents cover this topic well, insisting that you coordinate with other trades in the performance of your work. However, what is frustrating is when you are working a five-day work week and without any notice, the drywall sub or masonry sub decide to work over the weekend, resulting in allowances not being made for duct and pipe openings through walls. This impacts production because now you’re having to play catch-up and work around all these obstacles. Had you known these obstacles, you could have coordinated your work accordingly.
Then there is coordination avoidance. I have an older foreman working for me, and communicating with others is not his strong suit. We were performing the plumbing on a project that had a 20-inch high structure, but the ceiling in the area where we had the most work was only 9'0". To make sure that he did not interfere with anyone else, he hung all the piping 20 inches in the air. The closest duct, light or sprinkler pipe to us was 10 inches lower, BUT we did not have any coordination issues!
• Material handling — One can imagine the two or three typed pages of pipe, fittings and valves that might be on a major project for each system. We issue purchase orders to our vendors for the materials, and they ship them. But several things have to happen once we do that. The vendor has to key the order correctly; their warehouse staff has to pull the order correctly and put it all on the truck; they have to ship it to the jobsite; and it has to arrive when promised it would be there. Then there is the contractor’s side of this equation. We have to check in the material against the delivery ticket; then match the ticket to the purchase order that was issued; and then we have to put it an orderly manner in the trailer where we can send apprentices and helpers out there and find the material needed easily and quickly. But both sides are pressed for time — with multiple deliveries due at once, personnel issues, keeping up with other trades on the job or delivering material when you said you would, etc. It all boils down to planning.
With all these challenges, it is amazing sometimes that we get anything accomplished or make any money. I have tried to learn from mistakes of the past and make the effort to ensure a smooth process. Sometimes this works well, but many times the best effort on your part is not enough to make the entire process go smoothly. The saying goes to err is human but to forgive divine. Basically human beings are involved in everything we do in this industry. Having good relationships with all members of a project (design team, contractors, and vendors) can make all the difference in the world in determining whether the obstacles we face can be overcome or will defeat us!
Chip is president of Greene & Associates, Inc., mechanical contracting firm based in Macon, Georgia. Chip is a graduate of Mercer University with a BBA degree in management and has over 30 years of experience working on commercial HVAC and plumbing projects in the educational, medical, and institutional markets. His career started in high school working in his father’s mechanical contracting business, then working for a large mechanical contractor for six years before starting his own business 25 years ago. Chip is also presently serving as the 2016 National President of the Plumbing-Heating-Cooling Contractors Association. Contact him at email@example.com.