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Refrigeration Refrigerated warehousing A blurred line between service and design By John Carr Based on a 2003 United States Department of Agriculture study on refrigerated warehouses, there is about one square meter (10.8 sq. ft.) of refrigerated warehouse space for every man, woman and child in North America. And some of these facilities are huge – in excess of 18,600 square meters (200,000 square feet). All of this temperature-controlled space operates due to the efforts of refrigeration mechanics. These mechanics are constantly re-engineering to accommodate energy efficiency, expansion, new products, equipment changes and many more innovative or legislated modifications. An engineer may have performed the initial design of a refrigerated warehouse, but as time goes on the need for upgrading and updating systems falls into the domain of the technician. Two major refrigeration system types exist, ammonia-based, in general for warehouse operations exceeding 10,000 sq. ft., and fluorocarbon based, used in systems of any size but mainly those in restaurants, supermarkets and warehouses of less than 10,000 sq. ft. The large warehouses use ammonia as the refrigerant of choice for various reasons including refrigerant cost and the operat- The screw compressors are relatively new. These mechanics are constantly re-engineering to accommodate energy efficiency, expansion, new products, equipment changes … ing characteristics of NH3. All systems are operated within increasingly tighter parameters of government inspection, environmental concerns and increased safety awareness. This is leading to larger contracting firms performing services on the larger systems. The smaller units seem to be managed by small to mid-sized service and contracting firms. Smooth operation My experience in warehouse service work was all fluorocarbon based. One of my major service jobs was maintaining the refrigeration systems at Bridge Brand Food Services Ltd. This was back in 1970s – the “Freon days.” I returned to the operation in 2005 to review its changes as part of this article. To my surprise, the building’s exterior was the same, but the interior was a different matter (See Fig. 1). Whereas in the old days the systems were basically single systems with one compressor for each evaporator, today compressor racks supply refrigerant to an increasing number of evaporators. Chinook Refrigeration of Calgary is responsible for maintenance and ongoing design changes at Bridge Brand. Refrigeration mechanic Mike Mulhall, a student of mine back in the early 1980’s, is assigned to manage the systems. We toured the warehouse together, and then sat in the mezzanine cafeteria to discuss how the refrigeration systems had been redesigned over the years. In my service day there were two large freezers, several coolers and loading docks open to the outdoor air. The floors under the freezer/cooler rooms had electric heaters to prevent frost heaving in the ground. There was no leak detection, or other safety features. Forklifts traveled through somewhatclear plastic curtains. Fig. 1: Bridge Brand Foods in Calgary maintains different areas of its refrigerated warehouse at different temperatures. One memorable day saw me standing on a pallet loosely set on the forks of a lift. The operator lifted me up the 15-plus feet needed so I could inspect an evaporator drain pan that was spilling water onto the floor. The water had formed a small ice mound below, right in the driving path. The operator kept rocking the forklift to get over the mound. I clung to the grease-laden mast as it lurched forward and back a meter in each direction, screaming at the operator to stop. I lived and was well lubricated for the rest of the day. Safety, equipment upgraded Today safety is at the forefront of the operation. Technicians are enclosed in boxes that are raised to the coils with a forklift. Scissor lifts are used for major projects. Refrigerant leak monitoring equipment is used extensively. Door openings are now high-speed operations that automatically open and close as the forklift arrives and departs. Bridge Brand Foods utilizes these safety and automatic devices, but the changes are far more extensive. Bridge Brand now has six freezers with a total floor area of over 5,000 square meters (54,000 sq. ft.), five coolers with a total area over 2,230 square Huge evaporators supply air to the frozen food. (Photos/graphics by John Carr) Fig. 2: Unit 16 – Freezer with R-22 refrigerant meters (24,000 sq. ft.) and over 1,600 square meters (17,000 sq.ft.) of refrigerated loading docks. Fig. 2 provides a good example of today’s operation through a detailed look at the operation of one freezer. A monitoring system automatically calls Mike, or his backup, when the control system senses a problem. This reduces product loss and maintains customer confidence. Watch for further articles on this subject with troubleshooting problems and solutions included. John Carr is the continuing education coordinator at SAIT Polytechnic in Calgary. He can be reached at john.carr@sait.ca. 1. Space Temperature: 22°C (- 8°F) 2. Compressors: Hill Phoenix Screw rack with a capacity of 194 KW (660 MBTU/H) with 4 – 40 HP Carlyle screw compressors. 3. Evaporators: four coils at 48.4 KW (165 MBTU/H) with hot gas defrost. There are current sensing relays in the fan circuit of each motor. They signal high or low fan amperes to protect the compressor rack from liquid slugging and for early motor problem detection. 4. Condensers: 12-fan condenser split into three stages. a. Stage 1 is 50% capacity. b. Stage 2 is 25% capacity. c. Stage 3 is extra storage for maintaining a minimum charge. 5. Control system: CPC Einstein controller which monitors or controls: a. Inlet, outlet, drain line, hot gas inlet and liquid line temperature. b. Suction pressure. c. Compressor unloading for capacity control. 6. Compressor monitoring: Carlyle LonCEM electronic module: a. Monitors discharge and motor temperatures. b. Monitors suction, discharge and oil pressures. c. Controls liquid injection for motor and discharge cooling. 7. Under-floor heating: A glycol loop with: a. heat from a heat exchanger with a discharge-gas heat supply. b. A 1-1/2 HP pump. c. Supply temperature 9°C (48°F) d. Return temperature 3°C (38°F) 18 Plumbing & HVAC Product News – November/December 2005 www.plumbingandhvac.ca
Controls Pressure Transducer The Setra Multi-Sense Series Model 260 pressure transducer senses very low differential or gauge (static) pressure and converts the difference to a proportional electrical output for field-selectable uni-directional or bi-directional pressure ranges. Features include userselectable pressure ranges in fixed range performance, analog outputs and AC/DC excitation on voltage output operation. Alpha Controls Circle no. 316 models with relay outputs replacing triacs. Reliable Controls Circle no. 319 Fixed gas detectors The Crowcon Xgard Series of fixed gas detectors feature replacement plug-in sensors, a two-year sensor for oxygen monitoring, catalytic beads for combustible gases, electrochemical sensors for toxic gases and oxygen, thermal conductivity sensors for high-volume concentrations, sulphistors for hydrogen sulphide and high background gas levels. Crowcon Detection Circle no. 320 Fuel unit The Danfoss BFPS II Double-Cut fuel unit features electrically-controlled cutin and cut-off directly by the integrated solenoid valve, operates independent of the pressure regulator assembly, has a shut-off valve at the nozzle outlet, automatic bypass between one and two-pipe systems and a three gph rated filter. Danfoss Inc. Circle no. 321 Boiler control The A.O. Smith EMC-5000 energy management boiler control features adjustable two-stage firing, premium silicon nitride igniter, microprocessor display of all system temperature settings, diagnostics in English and touchsensor control switches. It is available on the company’s Genesis boilers from 300,000 to 750,000 Btu/h. A.O. Smith Water Heaters Circle no. 322 HVAC controller The CPU 1000 HVAC controller by HBX of Calgary requires no cross wiring for inputs or outputs and features arc suppression, graphing, pump sequencing, set points, DHW controls, colour-coded and key-indexed terminals and thermister inputs from outdoor-boiler-system sensors. HBX Control Systems Circle no. 323 Zone controller The IVAR Zone Controller, a product of Sydney, N.S., is a six-zone wiring centre for hydronic heating. Six angled terminal blocks (expandable to 12) provide easy wiring for thermostats and two-wire actuators. There is also a relay with an output for a circulator switching relay. Dip switches eliminate jumper wires. IVAR North America Circle no. 317 Control catalogue The Siemens’ Master HVAC Products Version 4.0 catalogue CD includes 700 pages of HVAC control components, valves, actuators, sensors, thermostats, damper actuators, VFDs, controllers, and accessories. Featured are SED2 variable frequency drives, RWD controllers, Q-Series temperature and humidity sensors and GND fire and smoke damper actuators, with product specification information, sizing and selection tools, technical data and application information. It is free at: http://www.sbt.siemens.com/hvp/Com ponents/ Siemens Building Tech. Circle no. 318 Control upgrade MACH-Vision controllers by Reliable Controls of Victoria, B.C., now feature Offer your customers all the advantages of advanced electronic controls - Taco’s innovative products make your job simple. Whether you’re looking for switching relays, zone valve controls, priority zoning circulators, or whatever, Taco’s extensive line of electronic controls are all designed to be contractor-friendly. They’re uncommonly fast and easy to install, with external indicator lights making them a snap to diagnose and service. Plus advanced expandable features allow you to mix-and-match to customize the system. At Taco, we’ve pushed the envelope in hydronic technology to produce a complete line of integrated products and controls to help you work faster and smarter. Ask your distributor about all the innovative advantages that Taco offers to you and your business. TACO CANADA LTD. 6180 Ordan Drive, Mississauga, Ontario L5T 2B3 Tel. 905-564-9422 Fax. 905-564-9436 www.taco-hvac.com ProFit Parts Mixing Valves six input and six output models, a non- LCD model with a set point adjust iSeries Software Radiant Mixing Circulators Air Eliminators Electronic Hot Water on slider for applications not requiring a Mixing Valves Blocks Controls D’MAND ® display. For the first time there are Circle Number 119 for More Information www.plumbingandhvac.ca November/December 2005 – Plumbing & HVAC Product News 19
Page 1 and 2: These adapters allow new rooftop un
Page 3 and 4: Features In This Issue Departments
Page 5 and 6: Hot Seat November/December 2005 Vol
Page 7 and 8: Industry News In Brief 13 SEER date
Page 9 and 10: Industry News New National Plumbing
Page 11 and 12: Industry News HRAI CONFERENCE REPOR
Page 13 and 14: Mid furnace line The Armstrong and
Page 15 and 16: Hot Water Heating Zoning strategies
Page 17: Hot Water Heating Integrated mixing
Page 21 and 22: 2618 * That’s the retail value of
Page 23 and 24: Faucets & Fixtures Four-litre flush
Page 25 and 26: Trucks for the Trade it morphs into
Page 27 and 28: Pipes, Valves & Fittings Waste pipi
Page 29 and 30: Tools & Instruments Economical root
Page 31 and 32: E-Business Piping design software V
Page 33 and 34: Industry News MCAC CONFERENCE REPOR
Page 35 and 36: People & Places People American Sta
Page 37 and 38: Mechanical Marketplace The bulletin
Page 39 and 40: Comfortably Ready... Our Ductless S

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