Courting Cooler Cabins

The main goal of the hvac restoration project was to provide guests with better control of the air temperature in their cabins in a cost-effective manner. Working within the confines of an operating hotel while minimizing inconveniences to guests, and attempting to use the existing ductwork systems, shoe-horning new systems within the restrictive working space of the ship’s extensive steel and bulkheads made the task particularly challenging. Additionally, ownership was in favor of eliminating the unsightly central station air handlers on top of the ship that had been added when it was permanently docked.

Thermal Engineering Group (Hendersonville, TN), a firm specializing in central plant design and district heating/cooling, was contracted as the ship’s energy consultant to select the proper solution. Says the company’s president, Harry Ragsdale, “Multiple approaches were investigated for installation and operating costs. The final solution was to use the existing vent trunk and ductwork, install new air-handling units (AHUs) with heating and cooling coils, and distribute air to the cabins using a thermostatic controlled variable-air volume (vav) system. Variable-frequency drives (vfd’s) were included in the AHUs to cost effectively provide the variable-air volume,” he added.

Thermal Engineering Group selected KMA Consulting (Costa Mesa, CA) as the local design consultant and Mesa Energy, Inc. (Irvine, CA) to perform the installation work. According to Wayne Lacher, project manager for Mesa, the primary challenge in the installation has been the quirky structure of the ship. “No two cabins match. You can have zig zags in the wall in one cabin, but in the next room the zig zag is a closet,” he says. “It’s like a big puzzle and we’ve got to make all the pieces fit, that’s what makes it fun,” Lacher adds. Since the rooms don’t match, the location of each vav box varies.

Another oddity is that each of the vessel’s staterooms had a grate in the door, which allowed air — and sound — to flow between the room and the corridor. Those grates were replaced with in-ceiling return air vents with sound attenuation duct work.

About half of the vessel’s 365 hotel staterooms have been retrofitted (35 to 70 are typically worked on at any given time so hotel operations can continue), with several of the common areas also completed. The results have been favorable. “It’s a very quiet system with no audible signs of fans or air compressors running in the cabins, and the air conditioning in the rooms that are finished has received very favorable reviews,” Ragsdale says.

Ship Automation System Onboard

According to Lacher, initially a single Andover LCX 810 controller with two EMX 150 expansion modules were installed at each AHU to provide standalone hvac control of the ship’s staterooms and reception salons. The LCX 810s monitor supply, return, and mixed air temperatures, space temperature, duct static pressure, fan start/stop, and status. The EMX 150s control the vfd’s speed, and stage the chilled water and steam valves for cooling and heating. Using the LCX 810’s local display/keypad capabilities, ship engineers can monitor each fan system and make setpoint adjustments.

Later in the project, an Andover CX 9200 network controller was added to network all the LCX 810s back to it via Andover’s Infinet field bus. Using a centrally located user terminal, ship engineers can now schedule certain AHUs off during unoccupied hours. (Previously, all AHUs operated 24 hrs a day.) By doing so, Lacher reports, the Queen Mary has been able to reduce its energy costs and shortened the run times of the central plant equipment.ES