So how does an engineer adapt a new technology? Adapting a new technology is not significantly different from dealing with some new element on a project, which happens frequently. A new element could be a new type or version of medical equipment, which has different utility requirements than the previous version. Or it could be a client desire to have part of the system work a little better than it has in the past. On a recent project, the client stated that there was a problem with the chilled water filtration for the MRI. If the water got too dirty, the magnet would shut down, which greatly worried the MRI staff. So we needed to research and figure out exactly wasn’t working and how to do it better, which filter to use, how to instrument it so switching out filters was seamless.
Sometimes, however, the engineer is required to design an entirely new system. When I ran my own business, the Owner wanted to use a ground source heat pump system, which I had never used before and since I was a single person company, no other resources in-house who had engineered this type of system. On a recent school job, the Owner wanted to use variable refrigerant volume. So how does the engineer design this system and ensure that the design is correct and field problems are minimized?
The first place we start is by talking to vendors. I like to thoroughly understand the technology. How does the variable refrigerant volume provide heating and cooling? What equipment is involved and does the application of the equipment differ from other applications? For a VRV system, the condensing unit is not fundamentally different than other heat pump condensing units, but the compressor technology is a little different. The ground source heat pump is a water source heat pump, operating at different temperature ranges.
Following the differences generally leads the engineer to where the potential, but as of yet, unknown problems might be. For a system which the engineer designs on a regular basis, typical problems are known and can be avoided by including certain things on the drawings. For a new system, it’s the engineer’s job to anticipate what these problems will be. For a VRV heat recovery system, the refrigerant is 410-A, which operates at a higher pressure than older refrigerants. This is a clue that potential problems could happen if the piping doesn’t have integrity, if the soldering isn’t good, or if the installing contractor doesn’t have good quality control. Also, leak testing of the piping prior to placing it in service will be important. A problem that we solved in the field on that job was that a potential location of leaks was where the small piping from the BS box connected to the VRV cassette. If the cassette wasn’t resiliently mounted, it would move a little when the fan cycled on, thus potentially breaking the connection. The solution to this problem was resilient mounting of the cassette and use of flexible copper tubing in the terminal refrigerant runs, which allow for some movement in the piping without rupture.
These days, I will also do a lot of googling and reading. When I first employed a ground source heat pump system, the piece which was brand new and thus, I needed to figure out where the potential problems could be was the ground loop and wellfield. I found very good resources on the web, took some free webinars, figured out who the industry leaders were and read several articles on their websites.
Talking to multiple vendors is also essential, and the experienced engineer can quickly figure out which vendors have technical competence and which have copycat products that they don’t fully understand, but they may be low bidding your project. For the VRV system, I talked to four vendors. Two emerged as the industry leaders, Mitsubishi and Daikin, and two others emerged as less experienced. Then, I visited several sites and asked the same questions–what problems have you had, does it maintain temperature well, how well did the installation go, etc.
Fortunately, in both situations I mentioned above with the ground source heat pump and VRV, it was not a public bid situation so I was able to pre-qualify contractors more thoroughly than I could have if the bid was public. From VRV vendors, I received lists of contractors who had performed multiple projects and interviewed them about their experiences, and visited jobsites to look at the quality of their work. For the VRV job, we obtained a commitment from the contractor that they would staff the job with a particular job superintendent who had VRV experience. So we went into it with a team approach, which is the best situation for the Owner.
By following these practices, engineers can successfully implement new technology and work towards a mostly problem-free job.