|
Green pump system
reduces energy costs
 As
energy costs continue to rise at an alarming pace, businesses
are turning their attention to strategies designed to reduce
energy consumption. An example of this is the hotel industry,
which can be a large consumer of energy given the number of
people they serve during any given night, amenities offered and
the large square footage of most buildings.
According to Xcel Energy, an electric and natural gas company
serving the western states, hotels 8,000 sq. ft. and larger
spend an annual average of $1.05 per square foot on energy. For
a full service or luxury hotel, properties may see energy costs
reaching 10 percent of their revenue! In a typical lodging
facility, lighting, space heating, and water distribution
represent close to 60 percent of total energy use, making those
systems the best targets for energy savings.
The Embassy Suites Hotel in Chicago is one of those luxury hotel
properties that fall into the category of “full service luxury
hotel.” Located in the heart of downtown Chicago, they offer 367
large suites, over 6,000 square feet of meeting space, indoor
heated pool, fitness center and a premier restaurant and bar.
During the 1970s, Embassy Suites installed a constant speed
domestic water booster to supply water to the building. Using
constant speed systems was a common practice during this time
due to the rudimentary control systems available on the market.
A constant speed system will run the pumps at a speed intended for
the highest demands even during low-flow periods such as during
the middle of the night. A typical system incorporates
pressure-reducing valves (PRVs) on the discharge of each pump to
maintain a constant system pressure. At any flow less than peak
flow, the pressure reducing valves will throttle flow and waste
energy. This is similar to pressing the gas peddle in your car
to the floor and controlling speed with the brake. This was a
popular solution for this era however, given the country’s
current green culture; this type of solution is considered the
“SUV” of the industry due to the amount of energy wasted.
The existing constant speed system was in dire need of replacement.
Not only was it noisy and a nuisance to guests, it would
constantly leak and would force some flush valves in public
bathrooms to run on their own or to not work at all. One 20HP
pump never stopped running, other problems included the constant
maintenance, and the possibility that the entire system could
fail given it was over 20 years old.
Green Design
Working closely with
Plumbing Contractor Emerald Mechanical, Metropolitan Industries
Chicago Sales Manger, Mike Ponx suggested installing a
variable-speed system that would reduce energy costs by half due
to the system’s ability to precisely match demand using only the
minimal amount of energy necessary. During low flow periods
where little or no demand exists, a variable speed system shuts
down entirely saving energy and money while a bladder tank
located on the roof helps maintain pressure, while the system is
in shutdown / low flow mode. Ponx was able to redesign the new
system based on a calculated flow.
“The chief engineer supplied a fixture unit count for the hotel and
we designed the system based on his flow requirements using the
fixture unit count,” said Ponx.
 The
new variable-speed, duplex domestic water booster system
consisted of vertical multi-staged turbine pumps each rated 280
gallons a minute (GPM) at 140’ of total dynamic head. System
capacity is 560 GPM with total system pressure of 90 PSI and a
suction pressure of 30 PSI.
The new booster system uses 1/3 less power than the constant speed
system. Not only does the new system sustain accurate pressure
by only running 1/3 of the time but according to the Assistant
Chief Engineer Jim Graehling, it saved the hotel over $2,000 on
the energy bill the first month!
“We witnessed a $2,000 reduction in our energy bill the first month
the system was operational,” Graehling said.
With the use of variable speed drives and low flow shutdown tanks,
the VFDs and pumps matched flow requirements and kilowatt usage
thus saving approx $2000 in energy consumption a month. More
importantly, pressures are stable and the control system is able
to hold accurate pressure within 1-2 PSI versus 20-40 pounds
swings using PRVs on the constant speed system. The other major
benefit using VFD control is eliminating PRVs no longer requires
maintenance and excessive costs associated with rebuilding them.
The life of the motor and bearings are extended as well
lengthening the life of the system overall.
Within a decade, the system will pay for itself based entirely on
energy-savings. The expected life of this system is over 25-30
years so eventually the system will not only pay the end-user
for the cost of the system but it will also pay the costs to
replace itself in its lifetime!
For more information on how you can reduce your energy consumption
while meeting the water demands of your building, contact Mike
Ponx at 815-886-9200.
|
