Built in 1873 and formerly known as the Bakeslee Mansion, The Ronald McDonald House of Connecticut in New Haven required a new HVAC system offering individual room control, energy efficiency, reduced operating costs, and improved IAQ. Its management selected a system that takes advantage of inverter technology by varying the compressor speed of the outdoor unit to meet changing load requirements in the indoor zones.
The Ronald McDonald House of Connecticut in New Haven has provided comfort, care, and shelter for thousands of children and their families from the U.S. and 36 countries. The 12-guestroom haven is a place where seriously ill children being treated at nearby medical facilities can stay for free or at a modest sum.
The 8,000-sq-ft, four-story wood-framed landmark structure was originally built in 1873. Known as the Bakeslee Mansion, it remained a family home for the next 50 years. Vacant for nearly 10 years, and in very poor condition, it was purchased in 1982 by The Ronald McDonald House of Connecticut. After a three-year reconstruction, the facility opened in 1985.
ALMOST 125 YEARS LATER ...
In 2000, complaints began surfacing regarding inadequate ventilation and the control of temperature, which prompted the facility's operations committee to investigate a new HVAC system that would deliver individual room controls, energy efficiency, cost savings, and improved IAQ. After an unsuccessful 18-month search for such a system, they turned to EMCOR Services Tucker Mechanical (ESTM) and to Tucker's field supervisor David Hamilton."After listening to the owner's objectives, and assessing the facility, we put together a comprehensive plan that provided innovative and cost-effective solutions," Hamilton said. They opted for the Mitsubishi City Multi system, which takes advantage of inverter technology by varying the compressor speed of the outdoor unit to meet changing load requirements in the indoor zones.
The City Multi's Control Network allows individual control of each indoor unit from a central location or inside each zone, a critical factor. Additionally, because the system is computer- and frequency-drive controlled, the facility became eligible for rebates from the local electric company, United Illuminating of New Haven.
NEW HVAC AND THEN SOME
The project, which began in March 2005 and was completed in June 2005, extended beyond new HVAC units. ESTM performed an evaluation of the existing hot water heating system and provided cost-effective solutions that enabled the system to run at its optimum. They repaired and/or replaced broken zone valves in the existing hot water baseboard heat throughout the building, reconnected several cabinet heaters, and installed an outdoor air reset and boiler control system by Basys control with domestic priority and pump rotation to provide hot water reset capability.Workers removed all existing mercury thermostats. All the baseboard heating zones for the common and office areas on the first floor and finished basement areas were interlocked with respective existing variable volume terminal (VVT) zone systems installed during an earlier renovation. The team also disabled the gas heat in the VVT rooftop unit, which is now used for cooling and ventilating air through the basement and first floor.
"Though it would no longer function as a combined HVAC unit, we recycled the equipment and employed it as a dedicated ventilation and IAQ system for the entire building," Hamilton explained. "We linked it all together into an integrated system for the first floor and basement using a heat interlocking relay in a box relay from Functional Devices. These solid state relays allow a minimum switching load on the VVT box triac outputs and enable those outputs to open and close the respective heating zone valves."
Next, they disconnected all the old rooftop condensing units and replaced them with Mitsubishi R-2 Series heat recovery variable refrigerant flow outdoor units. Due to the cost of removal, the team abandoned the existing ceiling ductwork and AHUs serving the second and third floor bedroom spaces. Recessed ceiling Mitsubishi evaporators were then installed in the individual spaces.
ANGLING FOR INDIVIDUAL CONTROL
The new design called for refrigerant piping to run from the roof to the attic above the third floor, and two Mitsubishi BC controllers, which serve as the main heat exchangers for the system, now reside in the attic. Connecting the second and third floor's indoor units to the BC controllers allows residents to individually control heating and or cooling at any time of the year without any predetermined mode priority. As on the first floor and basement, the team interlocked the existing hot water baseboard heat with the AHU as an auxiliary heat output fixed at 4ºF below the adjustable setpoint.In addition to operating effectively during single-digit outdoor temperatures and an above average summer season, the system is quiet and even with the significant turnover of guests, there have been no complaints, Hamilton added. "The system has worked flawlessly in terms of occupant comfort and we anticipate it will lower service and maintenance costs by 15%."
