Florida, like most southern states, has an abundance of sunshine throughout the year. Solar panels are quite popular as an energy saving strategy, generating heat for hot water for domestic or commercial use.
And like sunshine, heat levels are also high, frequently requiring air conditioning around the clock. Heat generated from the air conditioning cycle has traditionally been rejected via an outside condenser, but with today’s focus on energy conservation, this air conditioning byproduct is used to heat domestic hot water and other liquids as well.
Florida’s Marion County received a $2.45 million Federal Energy Efficiency and Conservation Block Grant as part of the federal stimulus program. The funds are available for a variety of energy savings programs, one of those being the installation of heat exchangers on the county prison water chiller.
For their first project, two Doucette Industries’ AC Series 125-ton desuperheaters were specified for one of two 250-ton McQuay air cooled R-134a chillers, one per circuit. Located in York, PA, Doucette Industries manufactures a variety of heat exchangers and other refrigeration equipment accessories. As with all purchases made under the stimulus grant, the equipment had to be certified U.S. manufactured. Doucette is also an ISO 9001-2008 certified company
Jim Scates, a Doucette representative from Clearwater, FL, said the Marion County prison project joins Disney World, Wal-Mart, and restaurants like Pizza Hut in adding reclamation equipment to their energy-savings plan.
“Our desuperheaters are simple, cost-effective devices that install quickly on to all major manufacturers’ cooling equipment,” said Scates. “Rather than routing the hot refrigerant gas to an external air- or water-cooled condenser, it goes through the desuperheater where roughly 20% of the heat is transferred to water circulating through the unit. It can heat water to 140°F or more by harnessing energy expelled from the air conditioning unit. The heated water is pumped and stored into one of three 1,000-gallon insulated storage tanks.”
Scates noted that the two desuperheaters raised the water temperature in one 1,000-gal tank to 140°F during the first night of operation. He said the units used on the chiller are no larger than a shopping cart and they operate very efficiently. Their compact design easily fits in most installations, and they are ready to install, saving on contracting costs.
As an example, a restaurant with a 10-ton air conditioning unit can heat about 70 gal of water per hour by 50 degrees. And the hot water is produced all the time — day or night — when the air conditioning is running, unlike solar heating.
Scates said there’s an additional cost benefit when adding a desuperheater.
“It reduces AC operating costs 5% to 10% and extends the life of the cooling equipment. Desuperheating removes part of the condenser load resulting in lower refrigerant temperature and pressure, reducing energy input to the compressor,” he said.
Andy Rance, facilities management director for Marion County facilities, commented that the county will save approximately $2,000 to $3,000 per month on energy used to heat their hot water alone at the prison facility — and that’s only from one chiller.
He also said the natural gas-fired boilers seldom come on now and it’s like free hot water. The jail uses the hot water in the facility’s kitchen and laundry areas.
The county has since added two additional desuperheater units to the second prison chiller. Their plans also call for upgrading the air conditioning units in most of the county’s 22 fire stations with heat recovery units as well as other county buildings. Desuperheating, as well as solar panel heating, has helped Marion County keep their operating budget in line.