The Boston Marriott Cambridge needed to replace more than 1,600 zone valves serving the fancoil units in its 431 guestrooms with new valves that could withstand the high shut-off pressures of its fourpipe hydronic system. Two-way electronic zone valves that incorporate an acutator were selected for the project.

As director of engineering for the Boston Marriott Cambridge, Robert Vass knows that each mechanical decision he makes for the hotel has 431 opportunities to fail. That’s the number of guestrooms at the hotel, located in the historic Kendall Square district of Boston. So when it came to replacing the more than 1,600 zone valves serving the fancoil units in all the guestrooms, reliability was his first priority.

Each hotel room has two fancoil units with hot and cold-water zone valves which open and close in response to the room thermostat. The existing 20-yr-old zone valves used an older technology and had begun to fail frequently, giving rise to numerous guest complaints about comfort.

Eschewing the Band-Aid

Replacing the old-style valves was a major undertaking, requiring costly outside labor, not to mention the fact that the room could not be occupied by paying guests while the work was completed. “We couldn’t replace these old-style valves without cutting into pipe,” said Vass. “We could change the motors, but because of the deteriorated condition of the valves, this was really just a band-aid.”

With over 430 guestrooms, it’s not practical to take a half-day to service a single valve. After all, a hotel wants to fill its rooms with guests, not service people. To that end, Vass also wanted a valve that could be quickly and easily serviced by his on-site maintenance staff.

Medford Wellington Service Company, Inc. of Medford, MA, was awarded the contract for replacing all the heating and cooling zone valves at the Marriott Cambridge. Tony Pasciuto of Medford Wellington Service consulted with HVAC controls distributor, Interstate Electric Equipment, to help him select new zone valves that would meet the hotel’s criteria. This included a valve that could withstand the high shut-off pressures of the hotel’s four-pipe hydronic system, which serves all 26 of the hotel’s guest floors.
In addition to the six RBI Futera Series boilers that provide hydronic heating, there is a 700-ton Trane variable flow chilled water system, all located in the 27th floor equipment room and 15 McQuay AHUs in the third floor equipment room. The zone valves also had to be readily available so that delivery could be easily coordinated with the hotel’s occupancy schedule.

“Delivery can make or break a project like this,” said Pasciuto. “No one likes to tell a hotel manager that your installation schedule has changed because a manufacturer can’t deliver a product on time. Luckily, that didn’t happen here.”

The Belimo two-way electronic zone valves selected for the Marriott project incorporate an actuator with a simple push button for quick removal. To further simplify servicing, Medford Wellington put unions in front of each valve so that, if necessary, the valve body can be removed without cutting into the pipe. Maintenance staff can simply slip them on and off with a wrench; no soldering is required.

A Sudden Drop ... In Complaints

Approximately 1,600 zone valves were installed at the Marriott Cambridge. Installations went quickly and easily, generally taking about one-quarter of the time it took to service the old valves. Vass credits Medford Wellington’s service and professionalism for helping to make the project a success. However, as with any hotel project, the ultimate yardstick for success is guest satisfaction. A sudden drop in guests’ complaints indicates that Belimo was a smart choice for the hotel.

“The fancoil units are working great,” said Vass. “Before the installations, the number one complaint we received from our hotel guests was about the heating or cooling. Now, I estimate that those complaints have dropped by 75% to 100%.”  In fact, Vass reported that the Marriott Cambridge guest satisfaction scores are currently the best of any hotel in Boston.ES