| Capital Projects Home Page |
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| Division 15 Mechanical |
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| 15-5 | Heating, Ventilating, And Air Conditioning |
| A. | Cooling Water |
| 1. | Cooling water from an industrial system or cooling tower does not require double check valves at equipment connections. |
| 2. | Where cooling water is supplied from a domestic cold water system, provide an approved double check valve assembly, installed before the point of connection to the equipment. |
| 3. | Pipe domestic or industrial cooling water waste to the sanitary system. For cooling water requirements, see Division 11. |
| 4. | Where cooling water with a high degree of purity is required for computer rooms, electron microscopes, or other sensitive equipment, provide closed loop system with a plate-type heat exchanger or a separate refrigerated system. Discuss with Planning, Design and Construction (CP). |
| B. | Hot Water Heating Systems |
| 1. | Provide for maintenance and repair work in the piping of hot water heating systems. Provide hose valves at the low points of the system to permit draining. Provide a safe, accessible drain as required in this division. Coordinate on location of drain. |
| 2. | Provide manual air vents at high points in hot water piping systems. Show or specify a valve ahead of all automatic air vents to facilitate replacement. |
| 3. | Show compound vacuum-pressure gauge and vacuum breaker on all hot water converters. |
| C. | Water Heating (Steam) |
| Where steam is available for water heating, provide a shell and tube heat exchanger (use plate type where applicable) meeting the following requirements: |
| 1. | Heater: 125 pounds per square inch, ASME stamped steam heat exchanger. |
| 2. | Materials: Non-ferrous for all parts having contact with water; and ferrous, cast iron or steel for all parts having contact with steam or condensate. |
| 3. | Controls: |
| a. | Control temperature shall maintain hot water set point temperature within +/-3°F for all flows from two gallons per minute through specified capacity. |
| b. | Provide high limit control that will shut off steam supply to heat exchanger with a 10°F maximum rise of outlet temperature above set point. |
| 4. | Provide each heat exchanger with the following: |
| a. | Compound pressure and vacuum gauge. |
| b. | Vacuum relief valve. |
| c. | Pressure relief valve. |
| d. | Thermometers in hot water outlet and return lines. |
| e. | Drain valves with hose thread adapter to drain shell and tubes. |
| f. | Thermowells in hot water supply and return lines to suit temperature sensors specified or provided by the Energy Management Control System. Install calibration wells (self-sealing test connections) adjacent to each thermowell location. |
| 5. | Design heater steam supply, condensate piping and trap to prevent coil flooding. Provide isolating valves, unions, and fittings, to permit easy removal of coils or heater. |
| D. | Piping System Cleaning |
| Steam and condensate piping shall be thoroughly flushed before placing in service, to remove dirt, rust, scale or other contaminants. Remove the works of all traps, regulators and reducing valves. Provide blank covers where necessary. Disconnect the condensate line ahead of the meter and direct condensate to drain. Circulate steam through the system for 24 hours to purge all contaminants. Then clean or replace strainers , reinstall trap, valve, regulator and reducing valves works and reconnect condensate meter. All cleaning work shall be done with the inspector present. |
| E. | Steam Pressure Regulators |
| 1. | Use the maximum steam pressure, consistent with operation and control, for steam-heated equipment. To prevent excessive steam velocity and objectionable noise, use two-stage reduction where the reduced pressure will be less than 60% of the initial pressure. Where a building program requires more than one pressure service, discuss the use of secondary regulators with Capital Projects (CP). |
| 2. | Provide steam pressure regulation and reducing stations in parallel pairs including unions, strainers, and gauges at both stations sized to match building feed line with adequate isolation valves to allow repair without interruption of building service. Include high, intermediate (if used) and low pressure gauges. |
| 3. | Regulators shall be 3/4" minimum and 2" maximum size, for all design loads of 1,000 lbs steam per hour and greater. Provide the number of regulators required for estimated load. |
| 4. | Consider the use of pneumatic-operated pressure regulators and temperature controllers at high pressure steam services. |
| 5. | Locate regulators in a safe location, accessible without the use of ladders or staging. |
| 6. | Detail the piping with effective unions or flanges, to permit easy removal of any regulator without disturbing other regulators or equipment. Do not provide bypasses at regulators. See Appendix. |
| 7. | Load Estimation: |
| a. | Average steam demand for all Berkeley campus buildings is 37 lbs of steam per hour per 1,000 square feet of gross area. If the estimated demand exceeds 40 lbs per hour discuss this with Capital Projects (CP). |
| b. | Do not add a warm-up factor to the estimated building demand when University buildings operate 24 hours per day. |
| F. | Water Treatment |
| 1. | Do not allow raw untreated water to be used in testing heating, ventilating and air conditioning piping systems. |
| 2. | All circulating water shall receive chemical treatment as follows: |
| a. | Heating hot water and chilled water for corrosion and stabilization. |
| b. | Condenser and cooling tower water for microbial growth, corrosion and stabilization. |
| 3. | Discuss chemical feed devices with Planning, Design and Construction (CP). Specify and detail approved chemical feed devices on the drawings. |
| 4. | The University will supply all required chemicals and supervise treatment of all systems. |
| G. | Gas Fired Heating Units |
| 1. | Provide gas-fired heating units with all necessary safety devices, including the following: |
| a. | Intermittent electric spark ignition with a thermocouple-energized device that will automatically shut off all gas flow to the main and pilot burners in the event that ignition is not achieved. |
| b. | Electrically operated control valve that will close, shutting off all gas to the unit, in the event that the temperature in the heater should rise above a safe point. |
| c. | Gas pressure regulator to maintain correct gas pressure at the burners. |
| d. | Manual shutoff valve to shut off all gas service to the heating unit. This valve should be a safe distance from the burners. |
| 2. | Provide gas-fired steam boilers with safety devices described above. In addition, provide a low water alarm and fuel shutoff system similar or equal to McDonnell and Miller. Include manual and automatic reset, low water and high temperature controls, dual gas valves, and other code-required items. |
| 3. | Separately vent each piece of gas-fired equipment. Size according to UMC. |
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