Question_&_Answers_B1270.docx

Remove and Replace Chiller at Bldg. 1270

TDKA 14-1108

Questions & Answers

1. Question: Please provide the Davis Bacon wages for this project. Or clarify if Davis Bacon is not required.

Answer: Davis Bacon wages is not required for this project. However, the Service Contract Act will be applicable for this project. https://www.wdol.gov/sca.aspx

2. Question: Please confirm that no Bid Bond, Performance Bond or Maintenance Bond will be required.

Answer: No Bid Bond, Performance Bond or Maintenance Bond will be required for this project.

3. Question: There is no isolation valves installed to isolate one pump at a time. All pumps will have to be shut off in order to replace a pump. Is it ok if all pumps are shut off and isolation valves on discharge side are installed at each pump than each pump will be able to get isolated? The valve installation might take 3-6 hours

Answer: Since there is a balancing valve above the check valve on the pump discharge riser, replacement of the balancing valve installed at each pump will be able to provide isolation. This balancing valve installation will require coordination with facility management and downtime of chilled water system.

4. Question: Is there glycol in the system and if so what percentage is it?

Answer: Per our records the current glycol level is at 14%, which is below our standard. For simplicity add 35% inhibited propylene glycol solution into system to fill system.

5. Question: Are the motor starters for pump staying or base is considering to switching to VFDs?

Answer: The base is going to stay constant flow and not switching to a VFD for the pumps at this time.

6. Question: Trane chiller can be internally programmed for chilled water setpoint and low ambient lock out. Will start/stop be adequate control over the chiller till controls are converted to BacNet?

Answer: Before controls are converted to BACNet, we would like to be able to proportionately reset chilled water with a 4-20ma or 0-10 VDC signal to chiller in addition to start/stop control of chiller.

7. Question: The existing system utilizes Johnson Controls N2 communications, while Statement of Work (SOW) and drawing mention BACNet communications protocol. What is required?

Answer: Johnson Controls makes a controller that will can communicate over either the N2 or BACNet protocols. While initially (for this contract) it will utilize the N2 communications, over time, Peterson can upgrade the building controls to all communicate with BACNet protocol.

8. Question: The SOW mentions in paragraph 2.3, replacing accessories between isolation valves on the pump installations, but there is only one isolation valve on discharge as part of header for all three pumps. The drawing of typical pump header doesn’t show this significant length of pipe between check valve and isolation valve. Please clarify what accessories and pipe is to be replaced.

Answer: The new accessories that are required for new installation include suction diffuser, pressure inlet gage, pressure discharge gauge, check valve and balancing valve for each pump. Overall chilled water temperature supply and return gages are required for header. To clarify, pipe can be reused between balancing valve and isolation valve on pump discharge.

9. Question: Please clarify pump controls to be connected in Metasys front end system mentioned in paragraph 2.3.

Answer: Our current standard for picking up status from the pumps upon start/stop is a current sensor.