Avoiding Downstream Problems with Upfront Data

Anybody involved with remodeling of existing buildings knows that they are full of surprises. Some issues are worse than others and some can completely derail a project (asbestos, anyone?). Less innocuous issues can still cause a brand-new remodel project to turn out less than desired.

One of the most common issues mechanical engineers run into is being told the existing systems are supplying the air and/or water services as expected. Whether it be a water or air system, the remodel engineer must rely on as-builts, information from the building engineer and what information can be gathered from the facility assessment to base their design off of; but what happens when that information is wrong?

Common Problems

Often the existing systems, for a whole variety of reasons, are not performing as they should. Chilled water may be leaving the chiller at 44°F but arriving at the remodel space at 54°F or it may appear that 200 gallons per minute is available but in fact only 30 gallons per minute is available. Possibly the chiller is simply not performing as it once did and now it only has 75% of its design capacity.

On the air side, it is common to find air handlers that should be producing 2,000 CFM but are only producing 1,600 CFM. As you can imagine, if the remodel mechanical design is based off the assumed capacity the problems will only become apparent towards the end of construction, or worse yet, once the remodeled space has been occupied.

Avoiding Problems

To avoid this, we recommend, encourage and occasionally require that a pre-design air and/or water balance be conducted.

The data from this effort does not need to necessarily be certified but using a skilled testing and balancing contractor will not only help identify any capacity limitations with the existing system but also may identify other HVAC or electrical issues with the system. This can benefit the project in a variety of ways but most importantly it can reduce change orders during construction and eliminate occupant complaints by ensuring the design documents identify all requirements necessary to deliver a completely functional mechanical system.

Design West can often complete the air side balancing ourselves; simply request it during the proposal phase of the project. Water side balancing takes special (read that as expensive) equipment so we can set you up with a TAB contractor we trust.

Justin Pardee