Just the facts in Amsterdam
Hotel guests expect high standards and high levels of comfort, which demands extensive heating, cooling and water circulation to the many rooms and bathrooms. This means hotels are pump intensive buildings and increases the potential savings that can be realised with a Grundfos pump audit.
With the facts and figures from the pump audit, the auditors demonstrated that the Grundfos solution would save the hotel 20,296 kWh/year.
The pump audit
At a 270-bed hotel in Amsterdam, Grundfos performed an initial pump audit on a booster set for the hotel drinking water installation. Having collected information and inspected the current pumping system, the Grundfos team arrived with its measuring equipment to carry out the pump audit. The equipment included ultrasonic, analogue and digital sensors, as well as advanced data loggers.
The team installed the equipment and left it in place for a week, though without affecting the operation of the drinking water installation. Measurements were taken at different times of the day and over a weekend, while the rate of occupancy ranged from approx. 50% up to 90%. This provided a comprehensive and realistic picture of the operation of the hotel’s current pump installation.
Results in black and white
After removing the equipment, the Grundfos team carried out a comprehensive breakdown and analysis of the data. Results showed in black and white that the current booster pumps were operating inefficiently. The pumps were not representative of the measured load profile and, as is often the case with older pump installations, they were tremendously oversized. Add normal wear and tear and the result was some very inefficient pumps.
The solution: Hydro MPC-E and big savings
Based on the data collected, Grundfos recommended a solution comprising Grundfos Hydro MPC-E 3CRIE 10-6 in a configuration with three pumps, where one is a reserve pump. The MCE control system would constantly calculate the most efficient operation mode. With the facts and figures from the pump audit, the auditors demonstrated that the Grundfos solution would save the hotel 20,296 kWh/year, reducing energy consumption from 26,762 kWh/year to 6,466 kWh/year. In fact, the design flow could be more than halved while providing savings of around 75%.
Savings of 33,686 kWh a year
At the 211-room hotel in Antwerp, Grundfos was called in to carry out a pump audit on the circulator pumps for the primary hot water system. The audit process followed the same method as for the hotel in Amsterdam - with one difference.
Installing the speed-controlled Grundfos solution would provide upwards of 70% energy savings on the hotel’s circulator pumps for the hot water system.
The Grundfos team immediately saw that the circulator pumps were operating at the exact same load 365 days a year, regardless of demand. This allowed the team to complete measurements in under an hour, measuring the power consumption in relation to discharge, suction and flow in normal operation and at the nominal duty point.
Beyond the required pump curve
The results demonstrated that the pumps in the existing installation were operating far beyond the required pump curve. Regardless of the actual requirements for hot water in the hotel, the pumps were circulating the same large amount of hot water day in and day out all year round.
The next step
To find the best possible solution the Grundfos team proposed an inventory of the secondary pumps to determine the sum of all flows against a specific factor for continuous operation. This could be used as the basis for calculating the correct size of an adjustment valve to be installed between the supply and return header of the collector.
Solution - speed controlled pumps
With this information, the correct pumps could be determined. But one thing was for sure, they should be modern, speed-controlled pumps. Already now, the team could calculate actual savings based on a possible solution with two smaller Grundfos TP125-60/6 vertical in-line pumps operating in an automatic cascade, controlled by a Grundfos MPC. The MPC controller would minimise energy consumption and further optimise performance based on pump curve data.
Energy costs slashed
The Grundfos pump audit quickly demonstrated that energy costs could be slashed. Installing the speed-controlled Grundfos solution would provide upwards of 70% energy savings on the hotel’s circulator pumps for the hot water system. Even better, the payback time at current energy costs would be no more than 2.5 years.