Baptist Health Systems
A Heat Pump Water Heater Success Story
Commercial laundries require a lot of hot water and are known for uncomfortable working conditions. This kind of environment can greatly benefit from a heat pump water heater. The Baptist Health Systems (BHS) Laundry in Birmingham, Alabama discovered that heat pump water heaters not only supply hot water, but also provide air conditioning to make working conditions more comfortable.
| The Problem | The laundry area was unconditioned and became extremely uncomfortable for employees. |
| The Solution | BHS chose to install the heat pump water heaters. It supplies hot water to tunnel washers while a duct system supplies spot air conditioning for individual work stations. |
| The Benefits | Since the installation of the heat pump water heaters, employee turnover and absenteeism rates are lower and employee morale has increased. |
| Analysis | Collection of the data occurred from August 1995 to August 1996. A Synergistic digital recorder collected heat pump kW usage, gallons of water, and cold and hot water temperatures. From this information monthly system Coefficient of Performance (COP), system costs and run-times were calculated. |
| Conclusion | BHS has recently announced a plant expansion. Because of the success of this heat pump water heater installation, BHS officials have listed heat pump water heaters as a "must" in their plans. |
The Problem
The BHS Laundry provides laundry service for several area hospitals and nursing homes in Birmingham. The laundry area was unconditioned and became extremely uncomfortable for employees. During the summer, indoor temperatures in the work space reached 110 to 120°F. It was so hot that employees left the building and stood outside in uncovered areas on the asphalt to get a break from the heat. The installation of large circulating fans in the work area did not reduce the temperature or make the conditions more comfortable.
Because of these extreme working conditions, employees often called in sick or did not show up for work at all. Employee morale and employee turnover were affecting BHS's business.
The Solution
BHS's management decided to make the work space more comfortable for their employees. To provide the necessary cooling, one company recommended the installation of 100 to 200 tons of additional air-conditioning.
BHS contacted Brian Wozniak of Alabama Power Company about the installation of the additional air-conditioning load. Brian recommended that he and a heat pump water heater specialist meet with BHS about their situation.
After reviewing the two proposals, BHS chose to install the heat pump water heaters. The heat pump water heater design consists of four 15 ton heat pump water heaters that supply 50 tons of air conditioning and 720,000 BTU per hour of water heating. The heat pump water heaters supply hot water to tunnel washers for pre-washing of soiled materials, while a duct system supplies spot air conditioning for individual work stations.
A small percentage reduction in the gas bills occurred after the installation of the heat pump water heaters. While the heat pump water heaters do displace some steam usage from the existing gas-fired boiler, substantial steam requirements still exist for other hot water usage, steam tables, etc. The reduction in natural gas usage by the boiler is therefore not substantial.
The Benefits
The installation of the heat pump water heaters provided spot air conditioning for work stations with temperatures between 75 to 80°F. The employees know that spot air conditioning is provided only when the tunnel washers are operating, providing for an incentive to keep the tunnel washers working.
Since the installation of the heat pump water heaters, employee turnover and absenteeism rates are lower and employee morale has increased.
Analysis
As shown in Figure 1, there are four 12.5 ton heat pump water heaters at the BHS Laundry. These four heat pumps make up the heat pump water heater system. The in coming city water mixes with preheated water in a 3,000 gallon storage tank. A central manifold distributes the water to the four heat pumps. After leaving the heat exchanger in the heat pump, the hot water circulates to a hot water manifold before being stored in the 3,000 gallon water tank. The water in the storage tank supplies water to the tunnel washers for the pre-wash cycle.
Figure 1
Collection of the data occurred from August 1995 to August 1996. A Synergistic digital recorder collected heat pump kW usage, gallons of water, and cold and hot water temperatures. From this information monthly system Coefficient of Performance (COP), system costs and run-times were calculated. Figures 2 and 3 show the monthly system COP and run hours. These graphs show that the monthly COP for the system is between 4 and 6 and the system operated between 200 to 350 hours per month.
Figure 2
Figure 3
An average COP of 4.51 was calculated for the heat pump water heater system using the collected data. Figure 4 shows an example of a typical heat pump water heater operation, with a COP of 4.51.
Figure 4
Figure 5 shows an analysis of the temperature difference between the cold water supply and the hot water from the heat pump system. From this graph we see an average monthly temperature difference between 5 to 9°F. Also shown is a maximum temperature difference for each month.
NOTE: The average monthly COP for the heat pump water heating system was 4.51, and the individual heat pump water heaters COP's ranged from 3.5 to 5.5. However, a typical heat pump water heating system has a COP of approximately 3.0.
Heat pumps operate at substantially greater efficiencies when providing lower temperature increases across their condenser coils. The temperature rise provided by these heat pumps is only about 10° to 15°F. A typical heat pump water heater installation provides a temperature rise of more than 60°F.
This installation would therefore be expected to have much higher efficiencies than a more typical heat pump installation.
Figure 5
Figures 6 and 7 show further analysis of the system's monthly operating cost and operations. Figure 6 shows an annual energy cost of $2,374.40, or $197.86 per month. From Figure 7 we see the laundry used 27.4 million gallons from August 1995 to July 1996, for an average of 2.28 million gallons per month, or 95,117 gallons per day. Figure 7 also shows an average monthly hot water temperature supplied to the tunnel washers of 83°F.
Figure 6
Figure 7
Conclusion
Because of the installation of the heat pump water heaters, the BHS Laundry has an improved working environment. The BHS Laundry increased production from 30,000 pounds of laundry per day to 40,000 pounds per day without any increase in staff. This increase in production cannot be confirmed to be a direct result of the improved working conditions. A change in operating procedures and the addition of customers also occurred during this monitoring period.
As can be seen from the above information, Alabama Power Company has a very satisfied customer. The installation of the heat pump water heaters created an environment that promotes productivity and saves the customer time and money.
BHS has recently announced a plant expansion for 1997. Because of the success of this heat pump water heater installation, BHS officials have listed heat pump water heaters as a "must" in their plans.
