I love design-build mechanical projects, and York Arts was one that presented many challenges. The basement level would be two large pottery classrooms with a third room isolated for the electric kilns, the first floor an art gallery and offices and the upper floor was to be classrooms and a large open space where lectures, painting classes or gatherings would be held. With such a diverse and wide-ranging load for maintaining thermal comfort, multiple zones would need to be created.
The electric kilns produced toxic fumes, so exhaust hoods and fresh air makeup were required. The exhaust hoods had to be raised when loading or removing pottery from the kilns and lowered to capture all by-products during the firing process. Counter-weighted pulleys and flexible exhaust ducts connected to the steel hoods are made for this exact application and provided the engineering criteria that enabled us to determine sizing for the combined exhaust line.
Challenges abounded because the York Arts building was in the Historic District, and given the basement pottery center was below grade and completely surrounded by other buildings, we needed to go up through the three floors and through the roof for the exhaust and fresh air intake. Fortunately, the steam boiler that once provided comfort was long gone and we convinced the architect and York Arts board of directors to locate the kiln room where the large brick chimney was located, providing a suitable chase for both the exhaust and fresh air conduits we could easily lower down the chimney from the flat rooftop.
The next challenge was the art gallery with loads of lighting affecting the cooling load. That required close coordination with the electrician in order to obtain wattage and what impact that brought to bear Btu/h wise. Single pane plate glass windows created the entire wall facing the street, and they were bumped out display areas with an additional floor, wall and ceiling exposure.
The rules in the Historic District dictated no changes would be permitted in order to maintain the original facade. Ductwork was to be concealed behind the gallery walls but could be exposed in the offices adjoining the gallery. Anytime ductwork is exposed to view, we like to utilize spiral ductwork, if ceiling height allows, and here we had to use a combination of spiral and traditional rectangular ducts depending on the ceiling heights for the kitchen and offices. Airflow is critical for the proper dispersal of conditioned air and to present a whisper-quiet delivery at all registers. Manual-D calculations with our custom friction factors were used to ensure balanced airflow. Choosing the correct registers for each of the outlet’s cfm (cubic feet of air per minute) for noise and proper throw (how far air will be sent from the face of the register) plus how many directions air will be directed would make or break the customer’s satisfaction with the installed system. Every manufacturer of registers provides the engineering specifications to aid in proper selection — a critical step in the design process.
As much as I really liked the advanced technology of the Triathlon heat pump, I also was worried about maintenance and potential repair issues. Upon returning home, I drafted a letter to the architect and York Arts board of directors expressing my concerns and reminded them that we do not provide a labor warranty on materials provided by others.
The top floor classrooms and large open area presented additional challenges regarding air distribution with constantly varying loads because each classroom had a maximum capacity for human bodies that are themselves little engines of gassing carbon dioxide and generating heat. The budget did not allow for VAV (variable air volume) boxes, but we were able to incorporate zone dampers with individual room sensors and remote thermostats in a locked access closet to prevent tampering. A weighted bypass relief damper enabled control of airflow as dampers opened/closed.
Fresh air was provided using an ERV (energy recovery ventilator) for each of the three floors and incorporated into the ductwork systems. This met the required cfm per square foot as well as per person and enabled the air handler’s blower if there was no existing call for heating or cooling.
The York Arts board president was a good friend of the head of York International, whose headquarters were in our hometown of York, Pennsylvania. During a golf outing, York’s president offered to provide — free of charge — two York Triathlon ultrahigh efficiency heat pumps. I had hoped for high-efficiency two-stage natural gas furnaces, A-coils and condensers. One hitch in the giddy-up was installers of the Triathlon heat pump were required to become certified via training and the next certification course was being held in Norman, Oklahoma! I had far too much time and money invested in the design-build process to lose the job over a certification, so off to Norman I flew. The instructor was also from York. He had all of us introduce ourselves and provide some background. He asked me why I flew to Norman when he was going to be teaching the same class the next week back home at York’s headquarters in York! Turned out he was joking.
The majority of our time was spent in the classroom going over the schematics and refrigerant circuitry. Aside from the expected components of an outdoor coil and indoor coil, the Triathlon heat pump also featured a hydronic coil both indoors and out because the compressor was actually a five-horsepower Briggs and Stratton engine converted to run on natural gas. An additional boost in the Triathlon’s operating efficiency was achieved by using an exhaust-to-hot-water heat exchanger, rendering a final exhaust temperature around 140° F.
A variable motor speed enabled VRF (variable refrigerant flow) to further enhance weather/load responsiveness and exceptional energy efficiency! With hydronic heating included, it was necessary to have the outdoor condenser hydronic coil to divert hot water to cool down during the summer air conditioning season. There were a variety of both high and low voltages and then there were also several DC (direct current) voltages to contend with if troubleshooting during future issues. Additional maintenance issues included changing motor oil, oil filter and spark plug with gap set using a gauge; and checking the pH of the inhibited glycol in the hydronic fluid. The training was indeed necessary!
We also conducted live-fire exercises. It was a cool day around 45° F with a light drizzle. The kind of weather we often see, although here in York, we often find we’re servicing broken-down heat pumps in subfreezing weather! Two of my classmates were from Las Vegas and told me they don’t work in cold, wet weather like we were experiencing. What about hot weather like you see in Vegas, I asked? Oh, we don’t work in hot weather either, they replied. Must be nice because we end up in hot attics during August where 140° F conditions are common. They gave me the look, as if to say I must be bonkers!
As much as I really liked the advanced technology of the Triathlon heat pump, I also was worried about maintenance and potential repair issues. Upon returning home, I drafted a letter to the architect and York Arts board of directors expressing my concerns and reminded them that we do not provide a labor warranty on materials provided by others. If, as I suspected, repairs might well be needed, we would need to charge for our time and materials. Unfortunately, multiple repairs did crop up. Cracked refrigerant copper lines within the heat pump, which resulted in the loss of refrigerant charge and I personally believed the copper tubing itself was the issue. Another golf game and York generously offered to provide new high-efficiency 2-stage furnaces and condensers. York also agreed to pick up the tab for our time and materials needed for the transition, which was more than fair for all parties involved. From that day forward, the systems performed flawlessly.
As it turned out, York Arts was being carefully monitored for its energy consumption by an outside expert and achieved recognition as one of the most energy-efficient commercial buildings in Pennsylvania during the time the two Triathlon systems were in use. York International eventually withdrew the Triathlon from the HVAC market.