Questions_and_Answers_0002.pdf

Earnest Coe VC HVAC Replacement

Pre Award Site Visit Q&A

1.Can we use a chain hoist to lift the condenser over the pedestrian bridge railing? I'm confident the structure is strong enough. We would like to avoid disassembly of the units to prevent unnecessary contamination. See photo with yellow area indicating where the chain host would be used. We would use high capacity cloth straps to hold the chain hoist to prevent any damage to the paint of the structure and use this to hoist the new condensers over the railing. Hoist shall not be used to lift HVAC condensers over rail.

2. Can we avoid cutting the interior floor for the refrigerant lines on the main unit to avoid the huge mess it would make and interfere with operations. We would prefer to go directly out the exterior wall and need to confirm that going out the wall and under the sidewalk outside will comply with the accessibility officer. See Photo. The cover for the new line location will stick out onto the sidewalk by about 7 inches before going under the slab. Not as much as the fire standpipe also shown in the photo with the yellow arrow. See additional photo for proposed new line set route across the mechanical room floor and confirm this will also be acceptable. We would install a cover over the piping to protect it. Yes lines can be routed as contractor sees fit if new installation does NOT present a tripping hazard or is protected by line set kit.

3. We cannot verify where the fresh air intake is for the main unit. Can we get original plans to review or have someone from the NPS confirm where the fresh air intake is and if it is adjustable. Fresh air is required by code, and we need to know if we have to include adding fresh air to the system to bring it into compliance. Attached contractors will find as built plans and original plans to the visitor center. Contractor shall replace HVAC system to code.

4. We need to confirm that the fire standpipe where we would be cutting the sidewalk doesn't run under the area the sidewalk will be sawed to make the new line set run.

Refer to the piping photo with the fire pipe marked with yellow arrow (above). Fire sandpipe runs straight out to pumphouse from behind column. It does not run underneath the area which would require cutting.

5. The 4 ton system has a single phase air handler, but the condenser unit data plate is faded, and we could not verify if it is single phase or 3 phase. Please advise as the bid request states 3 phase 4 ton but as stated the air handler is single phase. Condenser is 3 phase and only a single phase is used for condenser. There is availability for a 3 phase air handler.

6. We have discovered in the process of getting quotes for equipment to replace the existing units that the 7.5 ton system will have some questions moving forward. No brand offers a two condenser to one air handler option with A2L refrigerant. Now all the options are a single air handler to a single, either two stage, two compressor set up or a variable 2 stage condenser with a single compressor. The question comes in is that the existing system has two condensers at 4 ton. They are wired for that size condenser. Now we would have choice but to put a single 7.5 condenser which will have a significantly higher max overcurrent protection device (about 50-60) and a minimum circuit ampacity of around 40 amps. The wires serving these two condensers are inadequate for this new application.

Should we also get an electrician involved to pull a new wire if possible or can your team verify what options we have? If the contractor decides to go with a 3 phase HVAC unit they will have to rewire. If they decide to install a single-phase unit, they can possibly use the same conduit and might need to increase wire size at the panel. Either way it would involve an electrician.