TECHNICAL FEATURE will turn down the thermostat to reduce temperature only to find that the staff continues to complain. The experience is chalked up to a doctor who can't be satisfied when in fact this isn't actually the case. The complaint is often legitimate and the issue can usually be resolved. Table 4 lists the approximate chilled water temperature that must be supplied in order to maintain various combinations of OR space temperature and humidity. It is apparent that the space environmental requirements have a direct impact on both sizing and selecting the HVAC system, as well as what type of system can be used (chilled water, glycol or desiccant). Note that actual space load calculations are required to guarantee performance; this chart is only for approximation of temperatures. Many times a hospital's central utility plant (CUP) will be designed using more traditional leaving chilled water temperatures, such as 42°F to 44°F (5.5°C to 6.6°C). If both the hospital and the ORs are fed from the CUPs distributed piping network, problems can arise. It can be seen from Table 4 that there is a limited range of OR TABLE 4 Chilled water and supply air temperatures required to achieve various OR environmental conditions (based on 7°F/3.8°C chilled water to leaving air approach). SPACE °F DB SPACE RH% SPACE °F DP SAT °F DB CWT °F DB REHEAT °F DB CHILLED WATER 70 70 68 68 66 66 64 64 62 62 60 60 50 40 50 40 50 40 50 40 50 40 50 40 50.5 44.6 48.7 42.8 46.9 41.0 45.0 39.2 43.2 37.4 41.3 35.6 47.5 41.6 45.7 39.8 43.9 38.0 42.0 36.2 40.2 34.4 38.3 32.6 40.5 34.6 38.7 32.8 36.9 31.0 35.0 29.2 33.2 27.4 31.3 25.6 17.5 23.4 17.3 23.2 17.1 23.0 17.0 22.8 16.8 22.6 16.7 22.4 Yes Glycol Yes Glycol Yes Glycol Yes Glycol Glycol NA Glycol NA dew points that will be achievable using chilled water temperatures above 40°F (4.4°C). Clearly, attempting to provide cooler and drier conditions would be out of reach. In situations like this, two measures can be implemented. The first is to reduce the leaving chilled Grow your business with the power of a 100-year-old brand Panasonic HVAC solutions provide everything you need to cool, heat and save energy. Installing Panasonic means you're partnering with a trusted brand renowned for well-designed solutions, innovative technologies and unparalleled service and support. Residential Comfort EXTERIOS XE ductless systems do more than just heat and cool a home. They detect room occupancy as well as activity and automatically adjust temperatures to ideal comfort levels. Building Design Flexibility ECOi VRF systems give contractors, engineers and architects a modular HVAC solution that can grow with any building while lowering operating costs. Want to take the next step? Call us at 800-851-1235 and let's talk about growing your business with Panasonic. us.panasonic.com/hvac O C T O B E R 2 0 19 ashrae.org ASHRAE JOURNAL 23http://us.panasonic.com/hvac https://www.ashrae.org