If anyone has commissioned anything, it is very likely they have commissioned at least one VAV hot water reheat terminal unit. They are ubiquitous, they are commodities, and they are anything but “simple.” Just like the other “simple” systems addressed in this column recently, VAV reheat units are often marginalized and poorly documented in the design and construction process.
There is a sense that everyone knows VAV boxes, so what could go wrong? It isn’t that things can go terribly wrong, but it is a challenge to get them to go exactly right. Mostly in the interest of energy conservation, some building owners and operators have put a lot of effort into standardizing their terminal unit controls and want things done a very specific way. In addition to energy-conscious operations, the value of standardization cannot be overstated when the quantity of VAV boxes can be in the scores, hundreds, or thousands for a single owner.