RFI_Questions_and_Answers.pdf

RFI Questions and Answers

Q: The specifications do not indicate if exposed ductwork needs to be removed. What are we supposed to do with exposed ductwork?

A: Remove exposed ductwork along with heat pumps, accessories and electrical/gas equipment components to this equipment shall be removed. Utilize 02400 Demolition specification to restore areas to match existing. Ductwork going into wall spaces or attic/crawl spaces can be capped and abandoned.

Q: For the Vocational Building, what are the typical number of occupants in the classrooms? What are the room dimensions? We are looking to determine fresh air requirements.

A: The classroom occupants change frequently due to center student influxes. Plan for maximum capacities shown in the figure below.

Please also reference the attached Drawing for the Vocational Building, which shows building dimensions. Some of the interior walls have moved, so you will need to also refer back to the preliminary design document for this building that shows the current classroom configuration.

Q: Can we provide value engineering options such as utilizing ductwork in the houses and Tiller and the Dorms at Wolf Creek Job Corps instead of going with ductless systems?

A: “Value Engineering Change Proposals (VECP)” per FAR 52.248-3, Value Engineering, have specific requirements that must be fulfilled when being prepared and are submitted after the contract has been awarded. Prior to award, if a contractor chooses to submit a proposal that departs from the stated requirements, per FAR 52.215-1, Alternate II, you must fill out the Schedule of Items as was posted in the original solicitation. Submit a separate proposal that clearly identifies why the acceptance of such would be advantageous to the Government. Any deviations from the terms and conditions of the solicitation, as well as the comparative advantage to the Government, shall be clearly identified and explicitly defined. The Government reserves the right to amend the solicitation to allow all offerors an opportunity to submit revised proposals based on the revised requirements. Make sure to include the model numbers and efficiency specifications of the proposed heat pumps. Proposed heat pumps must meet the same or greater efficiency requirements and other salient performance requirements as the ductless systems. The contractor shall ensure that heat loss and heat gain load calculations are performed for every HVAC system installation/replacement.

For utilization of existing ductwork, provide a detailed description of how the existing ductwork with be cleaned and repaired to meet the following requirements:

• Proposing a larger unit to make up for losses in the ducting system are not allowed.

• Follow an appropriate methodology/procedure to perform building load calculations (e.g., ACCA

Manual J®, ACCA Manual N®, ASHRAE Handbook Guidelines, DOE EnergyPlus™, or other approved equivalents.

• Submit Load calculation worksheets

• New and replacement duct work shall be of galvanized sheet metal. Metal gauges, joints and reinforcement in accordance with Mechanical Code, ASHRAE, and SMACNA tables and recommendations.

1. Provide ASTM A-525 sheet metal with 1-1/4 oz. coating and bear stamp of manufacturer.

2. Tape joints of low velocity ductwork with fire resistant adhesive activated hardcast tape system. Hardcast, Vista or apply MP duct sealer per manufacture's recommendations for leak free joints.

3. Line all ducts with 1” thick Schuller “Linacoustic,” Gustin Bacon “Ultra-liner, “ or Owens Corning “Aeroflex” meeting NFPA 90A requirements.

4. Repair ductwork with AEROSEAL, mastic, metal-backed tape – NO DUCTTAPE.

• Ductwork Installation

1. Support all ductwork with 1” wide 16 gauge hangers not more than 8’ on centers or as required by code. Attach to available building construction according to good practices for material involved.

2. Install neoprene impregnated fiberglass connections in ductwork art all rotating equipment.

3. Construct elbows with throat radius equal to duct width in plane of turn or make them square and provide double wall, air foil turning vanes.

4. Caulk, seal, grout and/ or tape ductwork and plenums to make airtight at seams, joints, edges, corners and at penetrations.

5. Provide system free from buckling, warping, breathing, air leakage or vibration.

6. Plenums – construct sheet metal plenums and partitions of not lighter than 18 gauge galvanized steel and reinforced with 1 – 1/2” by 1/2” by 1/8” angles as required to prevent drumming or breathing.

7. Access – Install access opening and covers for cleaning, wiring or servicing motors, filters, fans both entering and leaving air side of coils, fire and/ or smoke dampers and to other equipment located within or blocked by sheet metal work.

• Flexible Duct Connections

1. Install in full-extended condition, free of sags and kinks, using only the minimum length required to make the connection.

2. Make all joints and connections with 1/2” wide positive locking steel straps or nylon self-locking straps and make connections to non-metallic ducts with sheet meal sleeves or manufactured sheet metal ‘spin-in” fittings.

• Leakage Test method:

1. CEC 1998 Low Rise Residential Alternative Calculation

2. Approval Manual Appendix F, P 400-98-003 all pressure measurement shall be plus or minus .2 pascals (.0008 inches of water), or 1% of reading, and a resolution of 0.1 pascals (.004 inches of water)

3. Letters of equivalence will be considered for other tests.

• Existing Duct Cleaning and Repair

1. Follow SMACNA HVAC Duct Construction Standards, Metal and Flexible

2. Provide remanufactured sheet metal patches that are hemmed and predrilled with insulation that matches the ductwork.

3. Duct sealing product must be specifically rated for sealing ductwork that meets NFPA requirements. AEROSEAL, mastic, metal-backed tape.

4. Seal modifications to existing ductwork in accordance with duct sealing described in

SMACNA HVAC Duct Construction Standards, Metal and Flexible.

5. Provide a HEPA-filtered vacuum collector system that is capable of maintaining up to 1 inch of static pressure inside the isolated area of ductwork.

6. Do not use any brushes that would damage the existing ductwork

7. Air Compressor as Required

The contractor shall select appropriate equipment for cleaning various HVAC system components.

The contractor shall repair or replace any system component that is damaged from excessive air pressure or water pressure resulting from the cleaning process.

• PREPARATION

1. Seal off ends and openings of any ductwork not being immediately worked on.

2. Isolate duct section to be worked on by using protective seal barriers within the ductwork to prevent loose dirt and debris from migrating to cleaned sections of the duct system.

3. Protect surrounding elements from being damaged and disfigured from work.

4. A synthetic filter media that is 1-inch thick and 30 percent efficient or an approved equal media shall be temporarily fitted over each register, grille and diffuser in the duct system to intercept any migrating loose dirt and debris.

5. Each work area shall be protected from dust and debris from ducts.

6. Dispose collected dirt and debris in an approved manner off National Forest Lands.

Restore each room to its original clean condition.

• CLEANING DUCTS

1. Work shall be conducted during non-business hours, unless otherwise approved by the COR or indicated in the Task Order. Coordinate duct cleaning schedule with the COR.

2. Take the fans off energy scheduling and allow them to run 24 hours, except when the ductwork is being cleaned.

3. Clean the outside air intake grille and shaft.

4. Clean the return air ducts. Begin at the outer ends of the return air system and end at the mixed air chamber and the exhaust stack.

5. Clean the interior of the air-handling unit. Remove and replace interior insulation at this time.

6. Install products in compliance with the manufacturer's instructions.

7. Pre-vacuum diffusers, grilles and registers in the ductwork. If necessary, remove the equipment, chemically wash/clean and reset.

8. ductwork using directional air nozzles and rotary brushes as necessary.

9. Clean the supply ductwork. Begin at the supply fan and end at the supply diffuser. At no point shall dirty ductwork be upstream from clean ductwork.

10. The COR shall approve the location of access holes and openings. Existing duct access panels shall be used wherever possible. Existing ductwork and insulation shall be neatly cut so personnel can easily access the ductwork and components for cleaning. As necessary, protect downstream areas from receiving particles during the installation of access points. After cleaning, the access openings shall be plugged airtight. The rectangular access openings shall be closed using overlapping galvanized sheet metal or material that matches existing ductwork. The cover shall be the same gauge thickness as the existing duct. The rectangular cover shall be fastened using self-tapping sheet metal screws with a silicone bead-sealing gasket. Seal all joints airtight.

11. Where ducts are provided with exterior insulation, neatly cut and remove. Insulation as required that accommodate required duct access holes and openings. When complete, insulate ducts again at access points and install new vapor barriers to match existing.