Entry # 12
Brief overview of the project
Two years ago a manufacturer of bottle handling equipment replaced their cast iron boiler with 4 high efficiency modulating condensing boilers. They also upgraded their air conditioning and replaced 8 window mounted units with a centralized system incorporating an air to water chiller and fan coils. Multiple Caleffi products were included in the project including ThermoCon, HydroCal, and QuickSetter.
To fix the heating, we replaced the tees with a Caleffi HydroCal. This decoupled all zone pumps and enabled full design flow. The air separation feature of the HydroCal also eliminated the distracting noise occurring in the large conference room that used panel style radiators. An air scoop had been used originally and was not able to keep all the air out of the system. For the cooling system, we re-piped a bit and installed a Caleffi ThermoCon buffer tank. This fixed the short cycling by keeping a chilled water reserve when a small zone called. On the chiller secondary, just above the variable speed pump, we installed a Caleffi QuickSetter. We kept this valve fully opened, which basically makes it a reliable, low cost flow meter. This helped us fine tune the ECM pump delta p setting. We had discovered the original pump setting produced excessive “erosion level” flow rates.
We were brought in and upon inspection of the heating system, it was evident the secondary pumps were not decoupled. The pumps feeding the smaller offices were being back pressured whenever one of the larger offices called - thus starving flow to the small offices. We found the closely spaced tees that the headers were piped to were undersized and positioned incorrectly. On the cooling system, everything seemed to be piped fine and the chiller sized correctly. The problem stemmed from a couple of the zones (restroom facilities and break room) being very small with little load.
The reported upgrades have been saving about 40% in total utility costs. The intermittent short-cycling of the chiller has been resolved and will improve the compressor life. The problem with some of the offices not heating during cold days is also resolved (in the winter sometimes the smaller offices would not heat up. The problem was more pronounced when all offices were occupied).