How you connect the plumbing between your process and chiller is more important than you might think. There are numerous considerations when connecting your chiller to your process. How you implement these considerations can affect your chiller’s pump life expectancy, energy efficiency of the chiller, nuisance alarm tripping, and cost of ownership, just to name a few. These are just a few key points to get you familiar with the basics. There are more areas directly related to how you install your chiller plumbing connections that could be expanded upon, but this is a place to start.
- DISTANCE: Key Word Short – Closed Loop Supply & Return connections are the main connections between the chiller and your process machinery / tool. The Supply and Return should always be kept as short as possible within reason of course. The short connection reduces the load on both the pump motor and the compressor motor. The reduced load makes it easier to push the fluid to its desired destination. The most important thing is that the supply and return plumbing have a lower pressure drop than the pumps maximum output
- LINE SIZE AND TYPE: Key Word Large – The larger the hoses or pipes connecting your chiller to the process the better. Large pipes or hoses reduce the load on the pump. A lower load requires less energy and increases the energy efficiency of the chiller. When you are sizing the lines for supply and return be sure do the following.
a – Look at the pressure drop across the plumbing you intend to connect, is it within the pumps pressure capability?
b – Is the pressure drop close to the pumps maximum pressure output?
If the answer to both questions is yes, reduce the load on the pump by increasing the inside diameter of the hoses or pipes. The larger the internal diameter (i.d.) connection the lower the pressure required to do the job.
Another important question to consider carefully is whether to use hose or pipe. Both Hoses and pipes have their own pros and cons.
Hose is generally easier to run, less expensive and using a hose may reduce the thickness of insulation required. Hose is manufactured from plastics, rubbers, or similar materials that transfer heat less readily than metal pipe. Hose is also more economical because it is can be installed by you rather than a professional which lowers the cost significantly.
The major benefit to metal pipes is the lower roughness value over synthetic materials like rubbers and plastics. Metal pipe transfers heat better and therefore requires greater insulation values to maintain the fluid temperature from the chiller to the process.
Metal pipe is often more expensive to install as well as you may have to hire a professional to install it due to local building and safety regulations. A final consideration with metal pipe is the required sharper bends than hose. This is important, as the sharper a bend is in a fluid path, the greater the pressure loss it creates.
- HEIGHT or HEAD LOSS: Key Word Vertical – The higher a pump must push fluid vertically, the greater the workload on the pump or the more pressure is required. For example, a pipe rising 10 feet requires 4.329 PSIG to achieve that height. Vertical rises should be kept as low as possible when installing the supply and return between the chiller and process, regardless as to whether you are using pipe or hose.
- FLUID VISCOSITY: Key Word Thickness – Fluid viscosity, or the relative thickness of the fluid you are pumping, must be considered. Viscosities are generally easy to find on the internet but be sure to find the viscosity at or close to the temperature you will be running the chiller. For example, water / glycol solutions are not very viscous at room temperature, but at lower temperature like -10 C and lower these mixtures can dramatically increase in viscosity making the pumps job much more difficult and reducing its overall output.
- INSTRUMENTATION: Key Word Measurement – Finally for many applications it is advantageous to spend extra on your plumbing installation for the chiller by including flow meters, pressure gauges and temperature measurement devices. In problematic applications these additions can save a lot of extra work, cost and lost time.
To summarize, these topics entail the main considerations when connecting a chiller to a temperature-controlled process. By taking these five areas into account you will possibly prevent having to completely redo your plumbing, save money in time and troubleshooting, save energy to power the chiller and possibly increase the life cycle of the chiller as a whole and especially the pump motor, all of which saves you money.