223500 - Domestic Water Heat Exchangers.pdf

09-01-20

22 35 00 - 1

SECTION 22 35 00

DOMESTIC WATER HEAT EXCHANGERS

PART 1 - GENERAL

1.1 DESCRIPTION

A. This section describes the requirements for domestic hot water heat exchangers including thermometers and all necessary accessories, connections and equipment.

B. Application is for indirect water heating utilizing steam.

C.

1.2 RELATED WORK

A. Section 22 05 23, General Duty Valves for Plumbing Piping.

B. Section 22 11 23, Domestic Water Pumps

1.3 APPLICABLE PUBLICATIONS

A. The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by the basic designation only. Where conflicts occur these specifications and the VHA standards will govern.

B. American Society of Heating, Refrigerating and Air-Conditioning

Engineers (ASHRAE):

90.1-2019...............Energy Standard for Buildings Except Low-Rise

Residential Buildings

C. American National Standard Institute (ANSI):

Z21.22-2015.............Relief Valves for Hot Water Supply Systems

D. American Society of Mechanical Engineers (ASME):

ASME Boiler and Pressure Vessel Code –

BPVC Section IV-2019....Rules for Construction of Heating Boilers

BPVC Section VIII-1-2019 Rules for Construction of Pressure

Vessels, Division 1

Form U-1................Manufacturer’s Data Report for Pressure Vessels

B1.20.1-2013............Pipe Threads, General Purpose (Inch)

B16.5-2017..............Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard

B16.24-2016.............Cast Copper Alloy Pipe Flanges, Flanged

Fittings, and Valves: Classes 150, 300, 600, 900, 1500, and 2500

PTC 25-2018.............Pressure Relief Devices

22 35 00 - 2

E. National Fire Protection Association (NFPA):

70-2020.................National Electrical Code (NEC)

F. NSF International (NSF):

61-2018.................Drinking Water System Components – Health

Effects

372-2016................Drinking Water System Components – Lead Content

G. Underwriter Laboratories (UL):

778-2016(R2019).........Standard for Motor-Operated Water Pumps

1.4 SUBMITTALS

A. Information and material submitted under this section shall be marked

“SUBMITTED UNDER SECTION 22 35 00, DOMESTIC WATER HEAT EXCHANGERS”,

with applicable paragraph identification.

B. Manufacturer's Literature and Data Including: Full item description and optional features and accessories. Include dimensions, weights, materials, applications, standard compliance, model numbers, size, and capacity.

1. Heat Exchangers.

2. Pressure and Temperature Relief Valves.

3. Steam Control Valves.

4. Thermometers.

5. Pressure Gauges.

6. Vacuum Breakers.

7. Steam Traps.

C. A Form U-1 or other documentation stating compliance with the ASME

Boiler and Pressure Vessel Code.

D. Shop drawings shall include wiring diagrams for power, signal and control functions.

E. Submit documentation indicating compliance with applicable requirements of ASHRAE 90.1, Unfired Storage Tanks, for Service Water Heating.

F. Complete operating and maintenance manuals including wiring diagrams, technical data sheets, information for ordering replaceable parts, and troubleshooting guide:

1. Include complete list indicating all components of the systems.

2. Include complete diagrams of the internal wiring for each item of equipment.

3. Diagrams shall have their terminals identified to facilitate installation, operation and maintenance.

22 35 00 - 3

1.5 QUALITY ASSURANCE

A. Equipment components in contact with potable water shall meet compliance requirements in documents NSF 61 and NSF 372.

B. Comply with American Society of Heating, Refrigerating and Air-

Conditioning Engineers (ASHRAE) 90.1 for efficiency performance.

C. The heat exchanger shall be certified and labeled by an independent testing agency.

1.6 AS-BUILT DOCUMENTATION

A. NOT USED

B.

PART 2 - PRODUCTS

2.1

2.2 SHELL AND TUBE, DOMESTIC WATER HEAT EXCHANGERS

A. The shell and tube heat exchangers shall be a single wall, semi-instantaneous type, vertical configuration with domestic water in the shell and steam in the tubes. Heat exchanger shall be of counter-flow design. The shell and tube heat exchanger shall be a packaged assembly of tank, heat exchanger coils, steam control valve, controls, and specialties constructed of ASME code, solid copper nickel shell with

155 psi ASME working pressure 210F test pressure. Heat exchanger shall comply with NSF 61 and NSF 372 for barrier materials for potable-water tank linings. Provide with access for cleaning and disinfection. Heat exchanger capacities are scheduled on the drawings.

B. The stand or skid shall be factory-fabricated for floor mounting.

C. The tappings (openings) shall be factory-fabricated of materials compatible with the tank and in accordance with appropriate ASME standards for piping connections, pressure and temperature relief valve, pressure gauge, thermometer, drain valve, anode rods and controls. The openings shall be in accordance with ASME standards listed below:

1. NPS 2 inch and smaller: Threaded ends according to ASME B1.20.1.

2. NPS 2-1/2 inch and larger: Flanged ends according to ASME B16.5 for steel and stainless-steel flanges, and according to ASME B16.24.

D. Factory shell insulation shall comply with ASHRAE 90.1 and suitable for operating temperature. The entire shell and nozzles shall be completely surrounded except connections, gauges and controls.

22 35 00 - 4

E. The heat exchanger coils shall be constructed from copper nickel and fabricated in a helix wound or straight tube configuration for steam heating medium. The pressure rating shall be equal to or greater than the 15 psi steam supply pressure plus 50 percent.

F. The temperature controls shall be designed for an output temperature of

140 degrees Fahrenheit based upon an adjustable temperature transmitter that operates a control valve and is capable of maintaining outlet water temperature within 4 degrees Fahrenheit of setting. Heaters shall be capable of raising the discharge temperature to 180 degrees

Fahrenheit for thermal eradication.

1. Steam control valve shall regulate the control of steam flow to the heating coil to control water temperature and shall be electronically operated. The outlet water temperature shall not vary more than +/- 2.5 degrees F.

2. A steam condensate trap, Y strainer, vacuum breaker, and pressure gauge shall be factory sized and piped with steam control valve.

3. A double solenoid high temperature limit system, with pre-wired control box, shall close the steam supply to the heating coil, should the water temperature in the tank reach the high set point.

4. The steam control valve shall have full BMS capability via ModBus.

G. Safety control shall be automatic, high temperature limit shutoff device.

H. The relief valves shall be ASME rated and stamped for combination temperature and pressure relief valves.

I. Accessories

1. All bronze circulator pump. 1/12 HP, 115v/1ph/60hz, with on/off switch overload protection for internal circulation ONLY.

2. 3/4” ASME Pressure and temperature relief valve preset at 150 psi &

210 degrees Fahrenheit.

3. 3/4” ASME Pressure only relief valve preset at 150 psi (shipped loose for field installation).

4. 1-1/2” float & thermostat Steam Condensate trap & strainer (shipped loose for field installation).

5. 1/2” auxiliary steam condensate drip trap.

6. 3/4” factory installed drain valve.

7. Vertical stand suitable for removal of heating section without disconnection of domestic water lines.

8. 3/4” factory installed vacuum breaker.

22 35 00 - 5

9. Operation & maintenance manuals in electronic form.

J. Provide factory authorized start-up and training (Excluding overtime, weekends & holidays).

2.3 CIRCULATING DOMESTIC WATER HEAT EXCHANGERS

A. A circulating pump complying with UL 778, all bronze construction, overhung impeller, and separately coupled inline pump shall be included. The pump shall have mechanical seals. The working pressure shall be rated at MINIMUM 125 psig. Refer to 2.2.I.1 All bronze circulator pump, ABOVE.

2.4 PLATE DOMESTIC WATER HEAT EXCHANGERS

A. Not Used.

2.5 DOMESTIC WATER HEAT RECLAIMERS

A. Not used.

2.6 THERMOMETERS

A. Thermometers shall be rigid stem or remote sensing, scale or dial type with an aluminum, black metal, stainless-steel, or chromium plated brass case. The thermometer shall be back connected, red liquid alcohol fill, vapor, bi-metal or gas actuated, with 9 inches high scale dial or circular dial 2 to 5 inches in diameter graduated from 40 to 212 degrees F, with two-degree graduations guaranteed accurate within one scale division. The socket shall be separable, double-seat, micrometer-fittings, with extension neck not less than 2 1/2 inches to clear tank or pipe covering. The thermometer shall be suitable for 3/4 inch pipe threads. Thermometers may be console-mounted with sensor installed in separate thermometer well.

2.7 SAFETY VALVES FOR SHELL AND COIL HEATERS

A. Separate combination pressure/temperature relief valve and pressure relief valve shall be provided on each water heater.

B. A double solenoid safety system shall be provided for each shell and coil heater to function as a safety over temperature prevention system.

System shall consist of aquastat, pilot light, solenoid safety valve and solenoid water safety valve located in the control circuit. The aquastat shall be set at 140 degrees F.

2.8 DOMESTIC HOT WATER EXPANSION TANKS

A. Not Used.

2.9 HEAT TRAPS

A. Heat traps shall be installed in accordance with ASHRAE 90.1 unless provided integrally with the heaters.

22 35 00 - 6

2.10 COMBINATION TEMPERATURE AND PRESSURE RELIEF VALVES

A. The combination pressure and temperature relief Valve shall be ANSI

Z21.22 and ASME rated and constructed of all brass or bronze with a self-closing reseating valve. The relief valves shall include a relieving capacity greater than the heat input and include a pressure setting less than the water heater’s working pressure rating. Sensing element shall extend into storage tank.

PART 3 - EXECUTION

3.1 INSTALLATION

A. Water heater installation shall be satisfactory to the COR, in every respect.

B. The water heaters shall be installed on existing concrete bases..

C. The water heaters shall be installed level and plumb and securely anchored.

D. Water heaters shall be installed and connected in accordance with manufacturer’s written instructions with manufacturer’s recommended clearances.

E. All pressure and temperature relief valves discharge shall be piped to nearby floor drains with air gap or break.

F. Thermometers and isolation valves shall be installed on water heater inlet and outlet piping and shall be positioned such that they can be read by an operator or staff standing on floor or walkway.

G. The thermostatic control shall be set for a minimum setting of 140 degrees F. for storage heaters.

H. Shutoff valves shall be installed on the domestic water supply piping to the water heater and on the domestic hot water outlet piping.

I. All manufacturer’s required clearances shall be maintained.

J. A combination temperature and pressure relief valve shall be installed at the top portion of the storage tank. The sensing element shall extend into the tank. The relief valve outlet drain piping shall discharge by air gap into a floor drain.

K. Piping type heat traps shall be installed on the inlet and outlet piping of the domestic water heater storage tanks, unless provided integrally with the tanks.

L. Dielectric unions shall be provided if there are dissimilar metals between the water heater connections and the attached piping.

M. Provide vacuum breakers per ANSI Z21.22 on the inlet pipe if the water heater is bottom fed.

22 35 00 - 7

3.2 LEAKAGE TEST

A. Before piping connections are made, the water heaters shall be tested at a hydrostatic pressure of 200 psig for water heaters rated at less than 160 psig. Any failed test shall be corrected and the water heater shall be replaced with a new unit at no additional cost or time to the

Government.

3.3 PERFORMANCE TEST

A. Ensure that all the remote water outlets are always tested to a minimum of 110 degrees F. and a maximum of 120 degrees F. water flow. If necessary, make all correction to balance the return water system or reset the thermostat to make the system comply with design requirements.

3.4 STARTUP AND TESTING

A. Perform tests ss recommended by product manufacturer and listed standards and under actual or simulated operating conditions and prove full compliance with design and specified requirements. Tests of the various items of equipment shall be performed simultaneously with the system of which each item is an integral part.

B. The tests shall include system capacity, control function, and alarm functions.

C. When any defects are detected, correct defects and repeat test at no additional cost or time to the Government.

D. The COR will observe startup and testing of selected equipment.

Coordinate the startup and contractor testing schedules with the COR.

Provide a minimum notice of 10 working days prior to startup and testing.

3.5 COMMISSIONING

A. Not used.

3.6 DEMONSTRATION AND TRAINING

A. Provide services of manufacturer’s technical representative for 1-day to instruct each VA Personnel responsible in operation and maintenance of the system.

B. Submit training plans and instructor qualifications.

- - - E N D - - -