AHU questions and answers 6-17-10.doc

(AHU Project Questions & Answers)

As of June 17, 2010 Q: 29 – Spec 15900 2.2 A.1 on page 35 states:

Precision thermistor may be used in temperature sensing applications below 200 degrees F. Sensor accuracy over the installed application range shall be within plus or minus 0.2 degree F or less, between the range of 32 to 150 degrees F. Stability error of the thermistor over five years shall not exceed 0.25 degree F cumulative. Sensor element and leads shall be encapsulated. (Bead thermistors are not allowed.) The maximum A/D conversion resolution error shall be kept to plus or minus 0.05 degree F. Total end-to-end error for a thermistor circuit shall not exceed 0.2 degree F, which includes sensor error and digital controller A/D conversion resolution error. Provide 18 gage twisted and shielded cable for thermistors.

A: 29 – This question was answered in item 23 of our 6-11-10 response

Q: 30 – “Looks like the data is still conflicting. The June 1 data called out 0.010 thick Aluminum Fins.

(1) The specification section 15761 calls out…

F. Fins: Copper, minimum 0.010 inch thick.

I. 7. Coating: Cathodic epoxy e-coat.

USA Coil and Air, the basis of design for the cooling coils, can provide one of the following choices.

0.010 Aluminum Fin with or without coating.

0.060 Copper Fin with or without coating.

The specified 0.010 Copper Fin is not available.

Typically we see the need for Aluminum coils with a coating OR copper fins without a coating. Please let us know what is actually required.

(NIST RESPONSE)Paragraph 2.1. F should read “Fins: Aluminum, minimum 0.010 inch thick.” to match existing coils. Paragraph 2.1.I.7 should be deleted. Special coatings are not required. Paragraph 2.2. F should read “Fins Aluminum, minimum 0.010 inch thick.” to match existing coils.

The June 10 answers calls out 0.060 copper.

Q 26- This is to confirm that the fin type is .010 aluminum without coating. Please verify.

RESPONSE: A: 26- Provide .060 copper fins without a protective coating.”

A: 30 – The fin thickness should have read” .006 copper fins without a protective coating”.

Q: 31 – For building 221, drawing note 1 on page 31 states that the fan, motor, cooling coil, heating coil and humidifier in ACU 1, 2, 5 and 10 have been replaced under a separate project and are new. This conflicts with the Equipment and Component Schedule on page 25. Furthermore, buildings 223, 224, 225 and 226 have similar contradictions between their drawing notes and Equipment and Component Schedules. Please clarify this issue.

A: 31 – First of all page 31 for Bldg 221 is a “control Diagram”. They referenced wrong sheet.

Second, the questions have been answered in our 6-9-10 response numbers 1,2,3,4, Q: 32 – For questions 26, you shown an answer of “0.060 copper fins without a protected coating”. I believe that should be 0.006”, copper fin is not available and not necessary in thickness of exceeding 0.008”.

A: 32 – Refer to answer A: 30.

Q: 33- The solicitation states that the Proposal form SF1442 is to be used as the "cover sheet or first page" of Vol. I, and that all volumes shall be clearly marked by volume number, title and original or copy.

Can we use our Cover Sheet identifying our Company, the Proposal with Solicitation No., etc. and the SF1442 behind that as page 1?

A:33-Response: That is acceptable.

Q:34- Can we use the first page only of the reps and certs if we are stating that Paragraph (d) applies, or do all pages of the reps and certs have to be included also?

A:34- Response: That is acceptable.

Q:35 - Para. 1.6.A. Reads “ Belts: One set(s) for each belt driven unit.” Questions: Is this considered a spare set, in addition to the initial set? Are TWO sets required per unit?

A: 35- Two sets are required per unit.

Q: 36- Para. 2.2.B.1. Reads “and support structure”. Questions: Please provide a description / definition for the “support structure”.

A: 36 The support structure referenced in para 2.2.B.1 is referring to the structural base of the fan itself which is a factory fabricated integral part of the fan.

The fans are mounted directly on the existing concrete inertia bases or new elevated angle-iron support frames as described on the individual ACU drawing sheets.

Q: 37- Para. 2.2.B.3. Reads Factory installed and wired disconnect. Question: Fans will need to be disassembled to fit into the building mechanical room and the ACU. It may be in the way during installation and assembly. Did the engineer want the factory mounted disconnect mounted on the fan housing? Please confirm that the disconnect is to be factory mounted.

A: 37- Delete para. 2.2.B.3

New disconnect switches shall be provided by the Electrical Contractor as specified on Electrical plans and Division 16 Q: 38 – Para. 2.2.D.1 Reads “ Single width-single inlet SWSI.” Question: Fans listed in the fans schedules are Backward Inclined Double Width fans. Please confirm that the fans are to be BIDW fans.

A: 38- Para.2.2.D.1 should read “single-width-single inlet and double-width-double-inlet”.

The types required are detailed and scheduled on drawings.

Q: 39 - Para. 2.2.H.1 Reads “access for inspection.” Question: Which particular access door is desired. Please provide addition information as to the specifc type required A: 39- Provided “hinged” (quick opening) access doors.

Q: 40- Para. 2.2.H.2 Reads “Companion Flanges.” Question: Fans are mounted in the ACU’s are companion flanges necessary?

A: 40- Inlet and/or outlet flanges are required where duct connections are shown to the fan. See drawings Q: 41- Para. 2.2.H.3 Reads “Variable Inlet Vanes.” Question: VIV’s are not shown on the detail. Please confirm that they are required.

A: 41 Inlet Vanes Dampers are required on all fans for manual balancing of system. Actuators are required for specified fans per control drawings. Variable Inlet Vanes are shown and documented on the control drawings.

Q: 42 – Para. 2.2.H.4 Reads “Discharge Dampers.” Question: Discharge dampers are not shown on the detail. Please confirm that they are required and where they are to be mounted.

A: 42- Discharge dampers are not necessary, follow contract documents.

Q: 43- Para. 2.2.H.5 Reads “Shaft Cooler.” Question: Shaft coolers are not used on BIDW fans. The shaft is in the airstream. It would serve no purpose to cool the shaft. Please confirm whether or not shaft coolers

A: 43- Para. 2.2.H.5 should read “Provide shaft coolers on all arrangement 1, 9 and 10 fans” where bearing are mounted out of Q: 44- Several previous comments referred to the coil construction as to fin thickness and material. Is there any chance a clarification as to what the final requirements are for the cooling and steam coils.

A: 44 Refer to last comment response.

Fin thickness is .006 copper.

Q: 45- There is not spec section for the Hot water coils. Please provide the construction requirements for the HOT water coils.

A: 45- There are hot water coils. The specifications are same as chilled water coils in para. 2.1 Water Coils.

Q: 46 – On Drawing 202-201, General Notes # 2 & 3, it is stated that "the new building automation system shall be integrated with the existing site Alerton Control system...(or) if not compatible with existing, shall include a new network system and operations work stations shall be provided ...(also) shall include a new network around the site...." This requirement of integration to the existing system will disadvantage other qualified 100% native BACnet complaint Building Automation companies. Will the government consider a system that meets the functional requirements of the specification but does not include a full integration or replacement of the existing system?

A: 46- The government will not accept a system that does not include a full integration to existing controls. The new system shall integrate with existing system. Contractor is responsible for all material, labor and software to ensure that full integration and a fully functional controls systems is in place.

Q: 47 – If the full integration or replacement of the existing system is required, will the government consider extending the bid date so that other vendors can complete a due diligence review of the entire site and the existing Building Automation System, with access to a list of all existing monitoring points, alarms, trends and programming language. This information will allow vendors to gain greater understanding of the existing system.

A: 47 – The proposal due date is to remain as June 21, 2010.

Q: 48- Amendment 4 Question 10 includes Exhibit #1 that listed the ACU height and width dimensions. Please confirm if these are exterior dimensions of the ACU or the interior dimensions of the ACU airstream. These dimensions are required for component sizing.

A: 48- Exterior dimensions are given for bidding purposes.

The contractor needs to field verify existing dimensions per specifications.

Q: 49- Can the exact specifications for the coils be re-released in their entirety?

A: 49- Exterior casing dimensions and interior framing dimensions are given on the contract documents. Contractor to size coil dimensions based on coil performance data provided on plans.

Q: 50- Specification Section 15837 – Centrifugal Para. 2.2.H.3 Reads “Variable Inlet Vanes.” Question: Some of the fan details have a note that reads “provide fan with Vortex damper”. Some of the details DO NOT have this note. Please clarify if ALL fans require the VIV’s as specified above, or if only the fans as noted on the details require the vortex damper.

A50: Yes, Inlet Vane Dampers are required on all fans for manual balancing of system. Actuators are required for specified fans per control drawings.

Variable Inlet Vanes are shown and documented on the control drawings.

Q: 51 – Bldg 245, ACU-1A Type D coil details conflict with ACU-1A Elevation A: 51- “ACU-1A Elevation” is correct.

Cooling coil should be Type C 1 high by 2 wide, steam coil should be Type A 1 high by 2 wide and hot water coil should be 2 high by 1 wide.