HVAC Narrative.pdf
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- Solicitation number
- 36C77625R0093
About this file
This is an HVAC Design Narrative for a federal construction project at the Dallas VA Medical Center. The project (549-21-700/2302) involves Electronic Health Record Modernization (EHRM) Infrastructure Upgrades requiring HVAC system installations and upgrades across approximately 126 telecommunications rooms and enclosures distributed throughout multiple buildings on the campus and three buildings at Herzog.
The design specifies Variable Refrigerant Flow (VRF) DX cooling-only ductless split systems as the basis of design for new telecom rooms, with wall-mounted indoor units served by outdoor condensing units sized according to heat loads from telecom racks (1 rack = 5kW, 2 = 7kW, 3 = 8.5kW, 4 = 10kW) plus lighting and structural heat gains. New telecom rooms will have one or two indoor units per room with shared condensing units mounted on rooftops or ground level. For existing telecom enclosures, new systems will be installed where necessary using single indoor units with dedicated condensing units. The project includes selective demolition of existing fan coil units, ductwork, radiators, and associated piping; installation of secondary drip trays with float switches and drain lines tied to BAS monitoring; and integration of new controls into the existing ECC system platform. Indoor design conditions specify heating at 81°F, cooling at 64°F, humidity between 30-60% RH, and positive room air balance. The project must comply with 2021 IMC and IPC codes, NFPA standards, ASHRAE 90.1 (2019) and 170 (2021), VA HVAC Design Manual (2021), VA Infrastructure Standard for Telecommunications Spaces (3.1-2021), and Physical Security & Resiliency Design Manual (June 2023). Testing will be performed during commissioning functional performance testing, with pre-testing not required. Equipment will be mounted with spring or in-shear isolation restraints, and seismic requirements will comply with VA Publication H-18-8 as determined by civil design.
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VA PROJECT NUMBER
PROJECT NAME
549-21-700 (2302) EHRM Infrastructure Upgrades – Dallas, TX
SUBMITTAL Final Bid Documents SUBJECT HVAC Narrative
Heating, Ventilating, and Air Conditioning 1
HEATING, VENTILATING AND AIR CONDITIONING (HVAC)
1. GENERAL
A. Spur Design is providing professional A/E services to design a compliant and complete construction and activation of a new Electronic Health Record Modernization (EHRM) system at the Dallas VA Medical Center. The mechanical design work encompasses the addition of new HVAC equipment or upgrades to existing HVAC equipment serving new or relocated Telecommunications Rooms. The existing HVAC equipment serving
TR’s that are to remain will be evaluated to determine if the equipment meets the EHRM requirements and any upgrades and remedies will be provided. The mechanical design includes replacement of HVAC equipment serving Telecom Rooms.
There are approximately 126 tele-data rooms located throughout the campus in
Buildings 1, 2, 2J, 3, 5, 6, 7, 8, 9, 11, 13, 43, 44, 45, 60, 69, 70, 71, 72, 74, 75, 77, 79, 80, 81, 82, TT46, TT47, TT48, TT49, TT50, TT51, TT52, TT53, TT54, TT55 and 3 buildings at Herzog.
New telecom rooms with telecom racks installed will have one indoor unit or two indoor units working together, served by a condensing unit. Condensing units are located on a case-by-case basis, with some being on rooftops, and some being located on the ground. Rooms with telecom enclosures only are to have their existing HVAC systems assessed on a case-by-case basis. If a new HVAC system is to be installed, it will be a single indoor unit served by its own condensing unit.
B. Existing System Description
1. Future Telecommunication Rooms – reference HVAC drawings for specific information.
a. The site investigation conducted by the professional A/E team determined that the existing systems serving future telecom rooms did not have the cooling density required or meet the design guide requirements to serve a telecommunication room.
2. Telecom Enclosures – reference HVAC drawings for specific information.
549-21-700 (2302) EHRM Infrastructure Upgrades – Dallas, TX
Heating, Ventilating, and Air Conditioning 2
C. Selective Demolition
1. Telecommunication Rooms – reference demolition sheets for specific information.
a. Existing fan coil units serving the rooms will be demolished.
b. All existing ducts, air devices, and accessories that are within the new TR room boundaries and not served from a dedicated AC unit will be demolished back to the main branch and capped. If ductwork or piping is serving another space, it will be rerouted. In the event a duct or pipe cannot be rerouted, drip trays, fire/smoke dampers, and security bars will be installed where necessary.
c. Existing radiators, unit heaters, and associated piping serving the TRs will be demolished.
d. Plumbing fixtures within TR spaces will be demolished and removed back to a point beyond the TR.
2. Telecommunication Enclosures – reference demolition sheets for specific information.
a. Existing room air conditioning systems to remain in place where possible.
3. Main Computer Rooms – are not in the scope of this project.
D. New System Description
1. Telecommunication Rooms
a. Basis of Design – Variable Refrigerant Flow DX cooling-only system with ductless wall mounted indoor unit(s). Indoor units will be served by associated outdoor condensing units. Condensing units will be roof mounted when necessary. Each new TR room will have one (1) indoor unit or two (2) indoor units working in tandem served by a shared condensing unit.
b. Units will be sized to account for the heat gain from the telecom racks (1 rack =
5kw, 2 = 7kw, 3 = 8.5kw, 4 =10kw), lighting load, heat load from walls/roofs/windows/etc., and electrical panels throughout the room. In rooms with telecom racks, multiple indoor units are used to prevent freeze up of the units. The DX split unit sizing will take derating into account. New units will be tied to the existing BAS system.
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Heating, Ventilating, and Air Conditioning 3
c. Secondary drip trays are being installed underneath all existing to remain mechanical, domestic, and sanitary piping as well as new refrigerant and condensate piping being installed in the rooms. The purpose of these drip trays is to protect the racks and various electrical equipment in the room. These drip trays will be connected to new drain lines with float switches that are tied to the
BAS monitoring the fill levels within each tray. The condensate lines will be routed to the nearest mop sink, floor drain, sanitary waste system, or outside to a condensate pit to meet project conditions and applicable codes.
d. Humidification to be monitored but not controlled.
2. Telecommunication Enclosures
a. Basis of Design – In places where a new system is necessary, a Variable
Refrigerant Flow cooling only system with ductless wall mounted indoor unit.
Indoor unit will be served by associated outdoor condensing unit. Condensing units will either be installed outside at ground level on a dedicated concrete pad or on a rooftop per structural mounting details.
E. Testing, Adjusting, and Balancing for HVAC
1. Pre-testing is not required for this project.
2. Final testing of systems will be performed and reviewed during the commissioning functional performance testing of the systems.
F. Vibration Control
1. New equipment will be mounted with spring or in-shear isolation restraints as required by VA AHJ and local codes.
G. Seismic Requirements
1. Seismic mounting, if required shall comply with VA Publication H-18-8 Seismic
Design Requirements. Seismic scope to be determined by civil.
2. APPLICABLE CODES AND STANDARDS
A. IMC – International Mechanical Code – 2021
B. IPC – International Plumbing Code – 2021
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Heating, Ventilating, and Air Conditioning 4
C. NFPA – National Fire Protection Association – 90A, 96, 99, 101 – 2021
D. ASHRAE 90.1 – Energy Standard – 2019
E. ASHRAE 170 – Ventilation for Healthcare Facilities – 2021
F. VA HVAC Design Manual – 2021
G. Physical Security & Resiliency Design Manual (PSRDM) – June 2023
H. VA Infrastructure Standard for Telecommunications Spaces (ISTS) 3.1 – 2021
3. OUTDOOR CLIMATE CONDITIONS
A. ASHRAE Climate Zone 3A (Moist)
B. ASHRAE 2021 Climate Design Conditions
1. Location: Dallas Fort Worth, TX (WMO: 722590)
2. Heating: 23.4 (99.6% °F DB); Extreme annual: 8.6 / 7.5 (°F DB/WB)
3. Cooling: 101.4 / 78.6 (0.4% °F DB/WB); Extreme annual: 112.9 / 84.0 (°F DB/WB)
4. Dehumidification: 75.4 °F / 135.7 / 83.8 °F (0.4% DP/HR/MCDB)
4. INDOOR DESIGN CONDITIONS
A. Per VA Design Guide/Manual:
1. HVAC Design Manual – 2021 – Room Data Sheets
2. OEHRM Site Infrastructure and End User Device Requirements V2.0 – 2021
3. Infrastructure Standard for Telecommunications Spaces V4.0 – 2023
4. Telecom Room Temperature Requirements:
a. Heating DB – 81 °F
b. Cooling DB – 64 °F
c. Max. RH% – 60%
d. Min. RH% – 30%
e. Room Air Balance - (+)
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Heating, Ventilating, and Air Conditioning 5
5. ENERGY SUPPLY
A. Electrical power supply available: Varies by building.
B. No Central Plant utilities will be utilized for this project.
6. CONTROLS
A. New unitary HVAC controls will be integrated into the current ECC system platform as part of this work.
END HVAC DESIGN NARRATIVE
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