It took a while for the spring weather to arrive in the Midwest, but now the temperature is quickly warming up, and we can finally say that the cooling season has started. In the HVAC world, that means it is time to start up your chiller(s).
If your goal this season is to maximize the occupants’ comfort in your building while keeping your operating costs as low as possible, then you should definitely follow some important steps to ensure an optimized startup.
The first one is to determine both your cooling load and the building load profile, understanding your load times and duration. This initial step is necessary in order to establish the desired performance of your equipment.
With this information in hand, you are then able to identify whether your equipment is adequate to the application or not. If your chiller needs to operate at full load to meet the desired performance, then I would invite you to consider replacing or repairing your equipment (check out our post about it here).
Except during the peak demand, a chiller should only operate 100% loaded in very particular or unfavorable situations that can be caused by issues with the equipment itself, such as insufficient refrigerant charge, or by external factors, such as a cooling tower fouling for instance.
Under the right conditions and the proper equipment, a chiller should operate at less than 60% capacity 90% of the time or more. Traditionally, the equipment has been designed for peak demand, but its best efficiency operation is usually at 50% of the load. This results in lower energy consumption, reduced operation costs, and improved equipment reliability.
Using a car analogy, it is like designing a car for the best fuel efficiency at 120 mph! You rarely drive that fast, so it makes more sense to design it for best efficiency where you operate most often.
Now imagine that you have already checked the cooling load and the building load profile, and came to the conclusion that you have the best equipment for your application and that you are ready to go.
Well, there is actually more ...
Even if you have been investing in regular maintenance during the shutdown period, you still need to pay attention to some important things before the startup, like commissioning and performance tracking.
When it comes to commissioning and performance, it is crucial to go back to the base readings, data, and the service history. This will help the technician identify and fix deficiencies. Believe it or not, the issue can be hiding everywhere, from an inefficient water treatment system to a clogged strainer of a pump. It is important to approach the original baseline, and to ensure that the unit has no internal degradation or wear of components.
Make sure to also go through the pre-commissioning checklist again and follow the manufacturer instructions.
1. Check vibration and oil supply
2. Replace oil filters
3. Clean and flush the pipe system and prevent debris from getting into the heat exchanger
4. Analyze the quality and the charge of your refrigerant
Lastly, do a comprehensive inspection for possible leaks, tightening electrical connections and identifying parts that need to be replaced. Always consult your owner's manual for any additional requirements.
A complete inspection of your equipment must be done by highly trained technicians, the same ones trained by OEMs. That is because drive and control components on a chiller are very complex, and any mistake can negatively impact your entire system. For example, insufficient refrigerant charge will end up in poor heat transfer to the evaporator, and too much refrigerant will affect the compressor and bearings.
When it comes to a chiller, attention to detail is the key. Chillers typically represent the largest power consumer in a building, making them the most logical equipment to consider when reducing energy costs. An inefficient equipment affects the unit operation during part-load conditions, increases ON and OFF cycles, and increases energy consumption, preventing your chiller to run smoothly.
This season, think of a chiller startup as an opportunity to save up to 30% in energy, to increase your equipment life, to reduce future maintenance costs, and to provide you with a great return on capital equipment investment - with actions that can be as simple as changing the sequence of your units, or changing the settings of an over sized chiller to optimize its operation under light load conditions.
We have a free Chiller Annual Energy Calculator that you can download to help you calculate how much energy reduction you could possibly have with an efficient chiller, and the impact of it in annual savings.