Contractors silences 'critics,' equipment noise
Krohn Refrigeration, located in Manalapan, NJ, does some air conditioning work, but only for its refrigeration customers. Founded in 1951 by Hans Krohn, CM, the Krohns are members of the Refrigeration Service Engineers Society (RSES).
The plan originally called for typical rooftop heating and cooling package units, and refrigeration condensing units on the ground outside. The architect had drawn the plans out this way and Krohn Refrigeration was ready to begin the work.
However, Sickles Farm Market, located in Little Silver, NJ, was having trouble getting final approval from the zoning board. The reason? Several residents living nearby raised concerns about noise from the air conditioning and refrigeration condensing units. That’s when the job got interesting.
Addressing concerns, soothing earsWith the original plans, the company could not guarantee that the noise value by the residents’ homes would be below 50 dB. It was time to rethink the project.
Richard Krohn, CM, Jean Krohn, CM, and Bob Krohn — all owners of Krohn Refrigeration — were involved in the design-build process and installation that focused on reducing noise. They decided that all of the compressors should be housed inside of a compressor room to lower noise levels.
“My experience is that the noise that travels the farthest are the deepest noises, and that’s what comes from the compressors,” says Richard.
An air-cooled condenser was chosen for the refrigeration rack since it would run year round. A water tower could have been used, but then the problem of keeping the water from freezing in winter and the threat of people slipping on any ice it created would have existed.
The company did select a water tower for the air conditioning; it had a smaller footprint and could be drained during winter months, when air conditioning was not needed.
The condenser and water tower were installed on the ground at the front corner of the building, as it was farthest away from the surrounding homes. The Krohns hoped that the building would keep the noise from traveling to the homes. This worked out well. “You can’t hear the air-cooled condenser or water tower at the houses,” says Bob.
The architect worked with the landscaper to create a “blind” to hide the units by planting evergreens around them. Richard cautions that the contractor who will have to service units hidden by shrubs and trees should be involved in the design. Otherwise, there could be problems down the road with the growing greenery interfering with the efficiency and serviceability of the equipment.
Keeping it coolBob Sickles told the company that he may not want to run all of the refrigerated cases year round.
In light of this fact, the company dedicated a compressor for each showcase lineup. The company wanted to avoid purchasing an air-cooled condenser with an individual pass for each compressor because it would require running six discharge-liquid return pairs out to the condenser. Due to its location, in direct view of the customers, this also would have looked sloppy.
The refrigeration system at Sickles Farm Market includes the following compressors:
- One 7 1/2-unit hp for the produce cases;
- One 3-hp unit for the island produce;
- Two 3-hp units for the two dairy cases;
- One 5-hp unit for the display freezer;
- A 1-hp unit for the deli case; and
- Another 1-hp unit for the bakery cases.
The system is unique because the compressors share a common condenser and receiver, complete with a flooded head pressure control system and oil separator, according to Richard. The oil separator returns oil to the compressors through Sporlan oil-level float controls on each compressor.
Where it differs from other rack systems is that each compressor has its own suction line from the case that it runs. A thermostat in the case controls a liquid line solenoid valve and only that case’s compressor will pump down and shut off.
This design allowed the company to avoid using evaporator pressure regulator (EPR) valves. Richard tries to avoid EPR valves whenever possible. “They tend to short cycle the compressor which will cause premature wear,” he says.
The design also makes it possible for each case to be shut off without affecting any of the others. Currently, one case at Sickles Farm Market is shut down and filled with a nonrefrigerated display. Jean also points out that it “saves the customer money in electricity by positively turning off a compressor associated with each case.”
The air-cooled condenser has an individual circuit for the freezer system that uses R-507. The refrigeration rack uses R-22.
Due to the length of the store and the location of the deli and bakery, the company was concerned that running suction lines for two 1-hp compressors over 150 ft was asking for problems with oil return.
The Krohns chose to have a separate, small compressor room for the deli case, bakery case, and one of the dairy case compressors. The room holds two 1-hp compressors and one 3-hp compressor, and has three small air-cooled condensers on its roof — one for each system.
One of Jean’s most important concerns is being able to easily service the equipment afterward, so “I’m always thinking about that while we’re doing the design layout and installation,” she says.
Cool heads, warm feetThe return ductwork of the air conditioning system pulls the air from the floor under the produce case line-up, allowing for removal of cold air off the floor in winter. Along with keeping customers’ feet warm, this design hides the return from view.
“There is nothing worse than cold feet,” says Jean. “If customers are uncomfortable when they’re shopping, they won’t want to stay any longer than they have to. This could have a negative impact on our customers’ sales.”
A 15-ton air handler and duct furnace is mounted on steel in the prep area. The supply ductwork is above the hanging ceiling in the store. A 15-ton compressor services the retail area, and a 4-ton compressor is dedicated to the office area.
There is enough capacity in the water tower to add a 4-ton compressor and air handler if needed in the prep area. Krohn Refrigeration also left room in its design for another water tower to be set outside next to the existing one for an expected store expansion this winter. Air conditioning suction and liquid lines have already been placed in the ceiling in preparation for the additional air handlers.
When discussing a new project, “You should always ask the customer if there may be expansions in the future,” says Richard. “This allows you to prepare for any changes in advance.”
According to Richard, you should also always be honest with the customer. His company comes right out and tells its customers that it does high-quality work, but it won’t be the cheapest bid they’ll get.
Richard says this saves the company and the customer time. If the customer is motivated by price only, they can shake hands and say goodbye. If the customer is more interested in quality than in price, they can sit down and discuss the project.
Coming off the experience with Sickles Farm Market, Richard also advises contractors to ask customers if noise is a concern for them and whether they want a design that will address it. Such a question could have saved three or four months of waiting for zoning approval on this project.
“Fairness and quality are ingredients for having an excellent relationship with your customer,” says Bob. Almost 50 years of being in business proves this point.