HVAC RETROFIT COMFORTS RESIDENTS AT CONNECTICUT RONALD MCDONALD HOUSE
The Ronald McDonald House (RMH) of Connecticut at 501 George Street 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 square foot, four-story wood-framed landmark structure was originally built in 1873 and was purchased in 1890 by the Lt. Governor of Connecticut, Dennis Albert Blakeslee. 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, The Ronald McDonald House of Connecticut purchased the property in 1982 and, after a three-year reconstruction, the facility opened in 1985.
In 2000, complaints began to surface regarding inadequate ventilation and the comfort and control of temperature. At this time, the facility’s operations committee decided to investigate a new HVAC system that would deliver innovation with respect to individual room controls, energy efficiency, cost savings and improved indoor air quality. After 18 months of searching unsuccessfully for a system that would provide the best solutions and address their needs, they turned to EMCOR Services Tucker Mechanical Meriden, Connecticut 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, Mr. Hamilton noted. “We looked at several options that would address the owner’s concerns and take care of their needs well into the future. Wanting to select the best system for our client’s needs, in the end, we 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 Mitsubishi City Multi’s Control Network allows individual control of each indoor unit from a central location or inside each zone a critical factor due to the unique comfort needs of each occupant. 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.
The project, which began in March 2005 and was completed in June 2005, involved more than the installation of the new HVAC units. EMCOR Services Tucker Mechanical performed a complete evaluation of the existing hot water heating system, and provided innovative and 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 base board heat throughout the building, reconnected several cabinet heaters, and installed an outdoor air reset and boiler control system by Basys control (# SZ2165) with domestic priority and pump rotation to provide hot water reset capability.
All the existing mercury thermostats were removed. All baseboard heating zones for the common and office areas on the first floor and finished basement areas were interlocked with respective existing VVT (Variable Volume Terminal) zone systems installed during an earlier renovation. The gas heat in the VVT roof top unit was disabled and 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 indoor air quality system for the entire building,” Mr. Hamilton explained. ”We linked it all together into an integrated system for the first floor and basement using a heat interlocking RIB (Relay in a Box) relay from Functional Devices of Russiaville, Indiana. 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, all the old rooftop condensing units were disconnected and replaced by Mitsubishi R-2 Series heat recovery variable refrigerant flow out door units. Due to the cost of removal, the existing ceiling ductwork and air handling units serving the second and third floor bedroom spaces were abandoned.. Recessed ceiling Mitsubishi evaporators (# PLFY) were then installed in the individual spaces.
Refrigerant piping was 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, were installed in the attic. The second and third floor's indoor units were then connected to the BC controllers to allow residents to individually control heating and or cooling at any time of the year with out any pre determined mode priority.
Nitrogen purging and pressure testing of the refrigerant lines was done to ensure there were no leaks in the joints or oxidation. To prevent the formation of acid, wax, and copper plating equipment related failures, triple evacuation to 400 micron was done to remove any unwanted moisture from the system.
"We calculated the necessary refrigerant charge based on the total length of the tubing and the diameters for each circuit, and charged it into the system while recording those amounts for future reference should a system require recharging,” Mr. Hamilton pointed out. “The digital addressing for all of the system's components was also set.”
As on the first floor and basement, the existing hot water baseboard heat was interlocked with the air handling unit as an auxiliary heat output fixed @ 4 degrees below the adjustable set point.
“The Mitsubishi equipment was easy to install because it only required the use of three-eighths and quarter-inch diameter tubing,” Mr. Hamilton noted “ 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.”
Some of the interesting aspects of the project include the fact that Mitsubishi gave the equipment to Ronald McDonald House at cost because the company wanted to introduce the product into Connecticut and use the project as a prototype. EMCOR Services Tucker was the design-build contractor, with design responsibilities that included determining routes for piping and sizing of equipment to meet the requirements of such a historic structure. In addition, the project was fast-tracked, with design being completed as equipment was installed, in order to accelerate the schedule.
“In the final analysis, Ronald McDonald House has been able to realize all of its objectives,” Hamilton pointed out. “The system has worked flawlessly in terms of occupant comfort and we anticipate it will lower service and maintenance costs by 15 percent. Savings on gas and electricity usage, which will not be determined until the system has been operational for a year, should also come in right were we expected.”
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System components include: one PURY-90TMU R-2 Series Outdoor Unit; one PURY-100TMU R-2 Series Outdoor Unit; six PMFY-10NBMU One-Way Recessed Ceiling Cassette Air Handlers; one PKFY-08NAMU Wall-Mounted Air Handler; nine PFLY-12NAMU Four-Way Recessed Ceiling Cassette Air Handlers; two CMB-1010NU-F 10-Circuit Branch Controllers; 16 PAC-YT51CRA Simple Controllers; one G-50A Central Controller; one PAR020MAU Wall Controller; one PAC-SC50KUA G-50A power supply; one CMS-MNF-B Maintenance Tool.
