Water Heating Tips
Consider Making Hot Water from Boiler Stacks
If there is a need for process heat within an operation, a heat reclaimer can be installed in the boiler stack instead of an economizer. A heat reclaimer is similar to an economizer in construction and installation. However, reclaimed heat is used to heat a fluid other than feedwater. This heated fluid then may be used in some other process. Process water is passed through the reclaimer to recover the heat in the exhaust gases. Because of the high temperature rise possible in the process water, the amount of heat transferred with the reclaimer can be considerably greater than with an economizer. Exhaust recovery systems and economizers should be used only when the stack temperature exceeds 350°F. If the stack temperature is allowed to fall below this level, corrosive fluids may condense and damage the stack and possibly the boiler.
Increase Water Heating System Efficiency
Although a hot-water system accounts for only about 4 percent of a building's total energy consumption (that figure is higher in buildings having a laundry or restaurant), increasing the system's energy efficiency is nonetheless worthwhile. The heater's energy efficiency can be raised; the storage tank, supply piping and recirculating piping can be insulated to reduce energy losses due to radiation, convection and conduction; water temperature guidelines can be strictly observed; and tenants can be encouraged to conserve. Energy savings can be achieved by placing water heaters close to usage points rather than installing one central generation tank and long runs of hot-water piping. To determine whether the installation of local units would be advantageous, analyze the building's hot water demand patterns. Next, estimate the existing system's total energy losses; then calculate the local units' potential savings. The energy saved is the sum of the reduced distribution losses and the increase in the average generation efficiency of local units, as compared to a central system.
Install a pressure-reducing valve when water pressure exceeds 40 to 50 pounds
When water pressure exceeds 40 to 50 pounds, consider having a plumber install a pressure-reducing valve on the main service. This valve will restrict the amount of hot water that flows from a tap.
Raise hot-water system efficiency
To save energy, raise the efficiency of the hot-water system by employing several strategies. Insulate the storage tank, supply piping, and recirculation piping; observe water temperature guidelines; encourage the tenants to conserve. In addition, an analysis of a building's hot water demand pattern sometimes indicates that placing multiple water heaters close to usage points is more economical than using one central tank.
Reduce Hot Water Temperature
Reduce generating and storage temperature levels to the minimum required for washing hands-usually 105°F. Boost hot-water temperature locally for kitchens and other areas where it is needed, rather than by providing higher-than-necessary temperatures for the entire building.
Reduce the Water Pressure
If water pressure exceeds 40 to 50 pounds, consider having a plumber install a pressure-reducing valve on the main service to restrict the amount of hot water that flows from a tap.
Use a heat reclaimer rather than an economizer for process heat
For process heat, install a heat reclaimer rather than an economizer, in the boiler stack. The amount of heat transferred by the reclaimer can be considerably greater than by an economizer. Note: The stack temperature must exceed 350°F to safely use either a heat reclaimer or economizer.