Feature article describing D’MAND CIRC product application and success of the utility funded rebate program.
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Commercial Building Products Article Text:
Are-circulation pump on a closed-loop line is the standard method in multi-family and commercial buildings to quickly deliver hot water to the tap. The pump pushes water at a high velocity from the heater or boiler to the rest of the building.
Over time, though, a traditional recirculation pump will accumulate many problems. The owners of the Oxford Club Apartments, Los Angeles, noticed the building’s energy bills rising and in addition, leaky pipes were discovered. They had a recirculation-pump problem. The combined effect of highly heated water and high pressure velocity causes an unnatural amount of friction against the pipes. This causes corrosion in the pipes, especially in older structures and systems. Pinhole leaks can result.
Recent investigations have identified recirculation pumps as one of the major contributors to pinhole leaks in plumbing systems. Repairing these leaks can be costly, because the source can be difficult to identify. Moreover, the problem is not noticed until it has caused some Significant damage to other systems in the building.
“When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints: said Jose L. Villalobos, P.E., founder and CEO of V&A Consulting Engineers, Oakland, CA. “In most cases, though, the primary, or even sole, culprit is excessive flow velocity.”
Since the apartment building does not draw water from a well source, and because a plumber confirmed that the building’s piping had been installed correctly, the owners were able to deduce that their recirculation pump was most likely to blame.
Apartment walls often contain cable, 40 COMMERCIAL BUILDING PRODUCTS OCTOBER 1009 www.cbpmagazine.com telecom, gas, electric, HVAC, security, and other service infrastructure. “A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences: said Villalobos.
Out-dated recirculation pumps can waste thousands of dollars a year because of ambient cooling. As the pump sends hot water throughout the closed-loop line of the building, the water’s temperature gradually cools before it arrives back at the heater or boiler. The cooled water has to be reheated before it can go out again, requiring extra gas to be burned for water that wasn’t even being used.
Since traditional recirculation pumps are always left running to ensure there is a constant supply of instant hot water, the reheating process is repeated again and again, throughout all hours of the day.
The solution lies in demand based technologies, or products that only activate when there is a need for the pump’s services. In this way, the amount of wasted energy and the amount of pipe erosion is reduced.
Enovative Group’s, Costa Mesa, CA, D’mand Circ demand-based pump uses temperature sensors connected to a return line and now sensors connected to a supply line to make decisions about the efficiency of its own operation. The pump senses when a faucet is opened, and monitors the ambient temperature from the return line. The pump uses the data to turn itself on and off. Even if the now sensor indicates that a faucet is open, the pump wi ll still only turn itself on if the temperature in the return line is not adequate.
The difference between running a pump based on demand and running it continuously is the difference between 1 to 2 hr. of runtime compared to 24 hr. This reduction in runtime makes the amount of corrosion produced by the pump’s now velocity almost negligible. Likewise, the number of reheating cycles caused by the ambient cooling is also reduced to a bare minimum.
If the water is not being continuously pumped throughout the building, but instead is stored within the heater or boiler during periods of long inactivity, less gas will be burned at times such as the middle of the night, when there is little demand for hot water. The advantage of demand based pumping is that these savings can be retained without limiting the actual times when . access to the water is demanded. So a tenant can still take a midnight shower without sacrificing the savings potential of the pump.
A D’mand Circ pump can be purchased at a subsidized rate, often free of charge, through regional gas-company incentive programs. Owners of the Oxford Club Apartments took advantage of the incentive program. The on· demand efficiency program from Southern California Gas Co., San Dimas, CA, paid for the cost of the pump and its installation.
Data collected over a wide range of field test sites indicate that the installation of a demand-based pump results in significant gas savings, as well as minor electric and water savings. The annual gas savings (measured in therms) can range from 20% to 30%. Electricity used to run the pump is also reduced.
After their plumber repaired the leaks and installed the pump, the owners of Oxford Club Apartments have had no incidents of leaking pipes. They are paying less for the building’s gas bill now than they were four years ago.