RFI__1-2-2a_Answers_0001.pdf

LOWE 339663 Install 2 Air Handling Units at Boott Mill #6

Solicitation RFP-140P4325R0046

September 9, 2025

9/05/2025 RFI #1 - Questions and Answers:

Subject: Mechanical room space constraints; replacement configuration; consideration of duct-mounted heating coil and potential consolidation of two AHUs into a single unit.

Background / Existing Conditions:

During site review and field measurements, a bidder observed insufficient clearance within the mechanical room to accommodate two side-by-side air-handling units (AHUs) as envisioned. The existing space limitations - including service clearances, egress pathways, and coil pull/access requirements - suggest that replacement in kind, maintaining the current physical orientation/configuration, may be the only feasible approach without significant architectural or structural modifications.

The scope also contemplates adding an additional coil in each unit. Given the already limited room envelope, placing another coil within the AHU casing appears to further constrain compliance with manufacturer service access, code-mandated clearances, and safe maintenance practices.

1. Replacement Configuration: Please confirm whether replacement in kind (retaining the same configuration/orientation as the existing units) is acceptable in light of the mechanical room’s physical constraints.

ANSWER: Replacement in Kind (maintaining the current orientation/configuration) is the intended scope.

Dual coils are intended for each unit/or in close proximity to the unit, preferably within the mechanical room.

2. Heating Coil Location: If the additional heating capacity remains required for each unit, please advise whether relocating the heating coil to the supply ductwork downstream of the AHU is acceptable to reduce unit footprint and preserve required clearances.

ANSWER: Yes, this is acceptable. Provide care to not install over the museum exhibits, for maintenance purposes.

3. Consolidation Option – Single AHU: Would the design team consider combining the two existing AHUs into a single, properly sized unit, with the following control/comfort measures:

Primary thermostat located in the WEAVE area (primary occupancy zone), and

A duct-mounted heating coil in the second-floor supply duct to mitigate over-cooling and maintain space neutrality.

Please also confirm that heating capability must remain available during summer months (for dehumidification/comfort control). If electric heat is not acceptable for this purpose, please indicate the preferred heating medium (e.g., hot water or steam) and any associated control sequence requirements.

ANSWER: SOW did not call for a combination of the units, so pricing for one combined unit is not required, but can be considered as an alternate if bidders provide a price and narrative for post award consideration. A second heat inducing coil is not preferable in the summer. This consideration shall be at no cost to the government.

4. Controls / Sequences: For either approach (in-kind with duct coil, or consolidated single AHU), please provide design direction on BAS points, sequencing, and interlocks, including: Summer heating enable criteria; Thermostat/sensor locations (WEAVE area primary, second-floor secondary); Coordination with economizer, reheat (if any), and dehumidification sequences.

ANSWER: Design can be developed to meet performance criteria as specified in 23 73 13.13-3; Part 2, 2.1 Performance Requirements. Thermostat/sensor locations can be proposed for approval. Sequences to be proposed for approval. Proposed Relative Humidity (RH) levels for the two units are to be kept 45%-60%.

Refer to ASHRAE; Chapter 24 Museums, Galleries, Archives, and Libraries for additional information (attached as a reference). The new units shall work with/integrate or bridge with the existing Trane controller system.

5. Clearances & Code: Please confirm the minimum service clearances and code/maintenance access criteria to be observed for the selected approach, including coil pull, filter service, fan section, and dampers—so the bidders can finalize layout without encroachment on egress or other systems.

ANSWER: Minimums are 30” personnel egress passage, 30” in front of working areas, and 36” in front of electrical panels/equipment under 600V. All clearance for serviceable equipment size is dependent on being able to pull out/install new filters, fans, dampers.

6. Electrical/Power Coordination (if electric duct heat is selected): Please confirm available power for any duct-mounted electric heater(s), including voltage, phase, MCA/MOCP, and breaker/fuse types, and whether panel capacity is available without upgrades. (If hydronic/steam is preferred, please confirm available capacity and tie-in location.)

ANSWER: Building power is 480/230 volts. There is capacity for options within the building, this can be confirmed once a design solution is determined. Bidder shall provide necessary power additions within available panels to meet new design – provide labor and materials in the proposal. The main electrical room is on the first floor, approx. 100 ft away. There is no steam system in the building. The boilers on the third floor are hydronic and shut down for the summer.

7. Bidder Proposed Approaches (for Consideration)

Alternate A – In-Kind Replacement with Duct-Mounted Heating Coil

Replace each AHU in the same orientation; relocate added heating coil to supply ductwork to maintain unit footprint and service clearances.

Controls: In-kind replacement would mean two (2) units with both spaces having T-Stat control.

Pros: Minimal architectural impact; maintains existing zoning.

Coordination items: BAS points list; TAB plan; access panels and drain provisions for duct coil;

insulation/condensation control.

Alternate B – Consolidated Single AHU + Second-Floor Duct Heating Coil

Provide one right-sized AHU serving WEAVE and second-floor; install duct heating coil on the second-floor branch to prevent over-cooling.

Controls: WEAVE thermostat as primary; second-floor duct coil modulates to maintain setpoint without adverse cooling load.

Pros: Potential equipment count reduction and simplified maintenance; may improve controllability.

Coordination items: Updated static pressure/fan horsepower; redundancy/maintainability considerations;

TAB and zoning verification; potential lead-time impacts.

Potential Impacts (Preliminary / Informational)

Schedule: Consolidated AHU lead time vs. two smaller units; coil procurement; BAS programming and TAB duration.

Cost: Potential savings from equipment consolidation may be offset by duct coil(s), controls, and electrical/hydronic tie-ins.

Access & Safety: Ensuring code-compliant access, egress, and maintenance clearances with the selected approach.

Commissioning/TAB: Include Pre-TAB and seasonal TAB (cooling and heating seasons) planning aligned with final sequences.

ANSWER: For bidding purposes, Alternate A (two units-replace in kind) is an acceptable method to meet the

SOW.

8. Requested Response Date

To avoid procurement and installation delays, please provide direction by September 8, 2025 (or if later response time needed, an extension of the bid due date may be required).

ANSWER: Bid due date is extended, shall be received (to Melvin_Gartrell@nps.gov) before Wednesday September 17, noon.

9. Attachments (if available)

Sketches indicating Alternate A (in-kind + duct coil) and Alternate B (single AHU + 2nd-floor duct coil).

Marked-up plan/elevation with proposed thermostat and coil locations.

ANSWER: None are to be provided at this time. The drawings provided are the only drawings available.

9/05/2025 RFI #2 - Questions and Answers:

Subject: Clarifications on TAB, duct construction/insulation, hydronic requirements, OA/economizer, outages, parking, and electrical service

1. Pre-TAB: Is pre-TAB (pre-testing, adjusting, and balancing) required for this project? If yes, please identify scope and standards.

ANSWER: Yes. Meet IBC 2024 and ASHRE codes.

2. Working Hours: What are the defined “working” hours and any restrictions (e.g., noisy work, hot taps, shutdowns, deliveries)?

ANSWER: Working hours are 7:30 am to 4:00 pm Monday - Friday, except national federal holidays. Any variation can be determined with a seven (7) day request and approval.

3. Existing Duct – Internal Insulation: Is the existing ductwork internally insulated? Please confirm locations/sections.

ANSWER: No, existing ductwork is not insulated.

4. New Duct – Insulation: Is new duct required to be insulated? If yes, please confirm internal vs. external insulation and applicable specification section/R-value.

ANSWER: New ducts are required to be insulated within the mechanical room only, and over to the new heating coil if in the museum space. All joints are sealed. Follow codes for R-values.

5. Double-Wall Duct: Is double-wall duct required for any new duct runs? If so, identify locations and specification.

ANSWER: No, double wall ducts are not required.

6. Chilled-Water Loop – Glycol: Is the existing chiller loop currently glycol? If yes, provide type and percentage. Can existing glycol be reused? If new glycol is required, please provide the bid quantity (gallons) and type.

ANSWER: Yes, Ethylene glycol. If any glycol is removed, it shall be replaced in equal amounts to match depletion.

7. Hydronic Valves & Specialties: Are all new valves and specialties required for hydronic piping (strainers, balancing valves, control valves, pressure/temperature ports, air vents, etc.)? Please confirm extent and spec sections.

ANSWER: Yes. Provide all new isolation valves both sides of the coils, pressure gauges, vents, etc. as necessary to complete a new system replacement.

8. Outside Air / Economizer: Is an outside air and/or economizer function required for the new system(s)? If yes, confirm sequence, controls, and minimum OA rates.

ANSWER: Yes. Provide design within the proposal listing minimum OA rates.

9. Acceptable Outage Duration (AC-2 / AC-4): What duration is acceptable for AC-2 and AC-4 to be out of service during changeover?

ANSWER: Install units in the April to June time-period or September to November period to limit supplemental heating and cooling.

10. Temporary Conditioning: Is temporary heating/cooling required during the outage period? If yes, define performance criteria (temperature/humidity range) and who furnishes/pays for temporary systems and power.

ANSWER: Depending on the proposed installation timeframe, temporary conditions could be required and paid for by the contractor. Small tools power can be provided by the Park.

11. Contractor Parking & Access: Can contractors park by the local access entrance serving this project? If not, please provide parking plan and material staging rules.

ANSWER: Yes, contractors (only vehicles needed to do the work) may park in courtyard adjacent to the L of the building. There is a public garage one block away for staff. During demo and installation, the area adjacent to the exterior louver can be blocked off, and public access can be rerouted. Cones, caution tape and signage will be needed. Prefer Hi-VIS Outdoor Crowd Control system by U-Line or equal. Fencing is not required. The park will provide internal re-route egress messaging to staff. No cutting or sprays allowed on the new sidewalk and asphalt adjacent the building. This work shall be done in a location in accordance with the CO’s approval. Building access and security controls shall be discussed at the notice to proceed.

12. Equipment Voltage – Verification: Please verify the existing AC-2 / AC-4 electrical service. We believe the units are 480V, whereas the SOW references 208V. Confirm correct voltage, feeder size, OCPD, and any required modifications.

ANSWER: 480V/3 phase is the existing power. Design and install new wiring back to the electrical room on the first floor.

13. 15% Over-Design Requirement: Does the 15% over-design requirement apply only to AHU/AC unit capacity, or does it also require corresponding ductwork upsizing (and coils, pumps, etc.)? Please clarify scope and design basis.

ANSWER: 15% gain in efficiency from existing units applies only to the new AHU/AC units. It does not apply to the ductwork or pumps.

9/04/2025 RFI #2A Questions and Answers:

1. Request for the serial numbers for the AHU units, or a picture of the air handler nameplate/tag.

ANSWER: See photos below.

ACU-4

ACU-4

AHU-2

AHU-2