RFI Questions and Answers.pdf

USFS IFG HVAC Repair

RFI responses and additional site photos provided by USFS:

Q1) The SOW description and the CLIN #’s don’t quite match. The scope of work it for Boiler / AHU / Controls. The CLIN# are for Boiler / AHU / Warranty. Can you please provide clarity in the pricing structure desired?

A1) The pricing shall be provided for the three (3) CLINs shown. You can provide pricing backup/details showing what you specifically include in each CLIN’s price, but the full job is to be broken out into the existing CLINS. The only controls work required for this contract is what is required to achieve boiler functionality with the existing system. Please refer to the PWS requirements and the drawings attached to the solicitation showing the existing controls installation for how the current boiler is controlled.

Q2) Can as built drawings be provided for the mechanical and electrical?

A2) All available drawings for the mechanical and controls systems were provided as attachments to the solicitation. Other as-builts were not available from the USFS.

Q3) Is there a bypass valve installed to work in conjunction with the DPT?

A3) The control system drawings provided as an attachment to the solicitation show a bypass leg for primary-secondary operation, but no valve in the bypass.

Q4) Can the data plate be provided on the building HW pump? Both the plates on the volute and the motor.

Q4) The USFS reports that the pump nameplate was faded and illegible, but the pump motor is a 3 hp motor. See additional photos provided by USFS below.

Q5) What it the designed delivery and return water temperature, and GPM for the HW system?

A5) In regards to water temperatures, the PWS requires, “Boiler temperature input and output setpoints must be set to enable boiler to operate in condensing mode to the maximum extent possible to maximize energy efficiency.”

There is not flow rate information on the available drawings, and the pump case nameplate is faded and unable to be read. The contractor will need to determine the flow rate per industry standards.

Q6) Can a building load calculation be provided or is the stated BTU load outlet to be considered sufficient?

A6) No load calculations are available, the output of the existing boiler is being used as the nominal heating required for the new unit.

Q7) What is the pipe size of the HWR and HWS to the building at the boiler skid?

A7) The pipe itself could not be uncovered without complete removal of the existing metal jacket and insulation. The existing boiler installation manual says the minimum pipe connection size is

2.5”. Additionally, the insulation jacket on the pipe has an outside diameter of 6-5/8” on the HWS and HWR pipes. Assuming insulation that is about 1.5” thick, the OD of the piping is most likely between 2.5-3”. The winning Contractor will need to field verify.

Q8) Are there 3-way valves installed at each of the fan coils?

A8) The control system drawings and air-handler data sheets provided as an attachment to the solicitation shows a 3-way valve at the air handler, and a 2-way valve at the other fan coils/terminal units.

Q9) Our Hydronic pump and boiler specialist does not necessarily recommend installation prescribed in the SOW as it will have a hard time meeting the efficiency desired on a predictable basis. They recommend a full flow boiler with a system pump only, depending on the temperature of the water you want to deliver to the building. A single full flow or variable flow boiler will provide a better predictability of maximum efficiency and one less pump for maintenance and repair. If the building supply temp is low enough, a high efficiency boiler can be used in a primary secondary arrangement, providing the building supply temp is no more than 160 degrees F.

A9) Installation shall be performed as prescribed in the SOW. The scope of this contract is limited to replacing the non-functioning boiler and making sure it interfaces with the rest of the existing system, so changing the whole system arrangement to a primary-only system is outside the scope of this contract.

Q10) The SOW call for repairing a leak in the existing McQuay unit. Is the location of the leak know?

This is a large variable as the area of the leak could be extremely costly and labor intensive.

Q10 The USFS reported that there is a refrigerant leak in the cooling section of the air handler that needs to be repaired (See Appendix B page 6 for picture of the area of the leak, CLIN 0002), and the system re-charged, that is the leak intended to be repaired within the scope of this contract. Any other air leaks in some of the ductwork seams and air handler access door seals are outside the scope of this contract.

Q11) Is water treatment of the HW loop to be included in the scope? Required for warranty by manufacturer.

A11) Whatever water treatment is required by the boiler manufacturer to maintain warranty coverage is required by the solicitation, a component of the contract is to maintain warranty coverage of any newly installed equipment (CLIN 0003).

Q12) Is Test and Balance of the HW loop to be included? Required for warranty by manufacturer.

Validating pump performance in order to maintain boiler warranty coverage is required, but other TAB work for the rest of the system is outside the scope of this contract.

Question 12A: On the main air handler repair, what refrigerant is preferred/used? We are not familiar with the ones listed.

A12A: The air handler nameplate shows that the unit was designed for and originally charged with R-22 refrigerant, which should be utilized for re-charging the system.

Question 12B: On the building automation system, what did you need replaced? Without proper diagnosis, we're unsure of what is needed.

A12B: The building control system work for this contract is limited to what is necessary to enable the new boiler to function properly with the existing system. The control drawings provided as an attachment to the solicitation show the following control sequence:

“Heating Hot Water System: The boiler shall be enabled whenever AC-1 is operating and the outside air temperature falls below 60°F (user adjustable).

During unoccupied periods, the boiler shall be enabled if the outside air temperature falls below an adjustable low limit setpoint (initially 35°F) to ensure circulation through the heating hot water coils at low outside air temperature.

A flow switch in the heating hot water return piping is factory hardwire interlocked to disable the boiler if there is no flow. The secondary hot water pump (HWP-1) shall be software interlocked to disable the boiler if the pump is not operating. HWP-1 shall run for at least 5 minutes (user adjustable) after the boiler has been disabled due to lack of demand. The boiler shall operate when enabled by the Temperature Control and Facility Management System (TCFMS) only through its own safeties. The TCFMS shall monitor the status of HWP-1 and report if the status does not match the commanded state.

Secondary hot water pump (HWP-1) VFD shall modulate to maintain the differential pressure at the heating hot water coil serving VAV-3.

Trends:

Boiler Supply Temperature Heating Water Loop Supply Temperature

Alarms:

High Heating Water Loop Supply Temperature Low Heating Water Loop Supply Temperature High Boiler Supply Temperature Low Boiler Supply Temperature Boiler Alarm Boiler Failure Secondary Heating Water Pump Failure Low Secondary Heating Water Loop Pressure”

Photos from USFS of boiler location and shade structure.

Figure 1. Access to boiler tall side 54'

Figure 2. Boiler concrete slab length

Figure 3. Boiler concrete slab width

Figure 4. Boiler heating supply pump

Figure 5. Boiler roof corner

Figure 6. Boiler roof joist

Figure 7. Boiler shaft motor

Figure 8. Boiler tank height

Figure 9. Distance to boiler from wall 33'

Figure 10. Historic Wall Height 36"

Figure 11. Historic wall height 40"

Figure 12. Historic wall measurement

Figure 13. Shade structure length 20'

Figure 14. View of access to boiler

Figure 15. Photo of insulation support strap showing OD of exterior pipe insulation.