697DCK-21-R-00338 Amendment 1 Q and As.pdf

697DCK-21-R-00338

AEX HVAC Replacement, Alexandria, LA

Questions and Answers

Question 1: During the pre-bid walk thru, it was mentioned the AHU systems can be taken down for approximately 15 minutes to convert the units to the new control panel. Please confirm.

Answer 1: Due to equipment delivery times, it is highly likely that this work will not commence until the cooler months of the year. As a result, the air conditioning units can be taken off line for a period of time that is equals to or exceeds 15 minutes (depending on outside air temperature).

Question 2: According the local York rep, there are three different fan options with this AHU: 5 HP (Low Static), 7.5 HP (Medium Static) and 10 HP (High Static) and the scope of work indicates the new York AHU should have a 5 HP motor. According the nameplate on the existing Carrier AHU, the existing AHUs have 10 HP motors. With the addition of the backdraft dampers (some in the vertical and some in the horizontal), please confirm if the new AHU should have a 10 HP motor.

Answer 2: York 30-ton AC units were installed at AEX prior to the installation of the existing Carrier units. The old York units had smaller fan motors. However, the duct system was also replaced at that time, resulting in a higher system ESP. The 5 HP motor should maintain SP, however increasing the motor size to 7.5 HP would compensate for any unknown increases in airflow resistance without significantly increasing equipment cost.

Project scope change:

Refer to section 1.2, item II(a) in project specification: Change the following: with Field Installed Motor Drive Kit, Drain Pan, Low Static Drive (contains sheave and belt), Motor-VFD rated 208-230/460 Volts, 3 Phase, 5 HP and Motor overload relay Kit, or approved equal.

To: with Field Installed Motor Drive Kit, Drain Pan, medium static Drive (contains sheave and belt), Motor-VFD rated 208-230/460 Volts, 3 Phase, 7.5 HP and 7.5 HP Motor overload relay Kit, or approved equal.

Question 3: Drawing M008 indicates a 25 KW electric heater in the SA ductwork for the new AHU. According to the local York rep, this heater is not provided by York and should be provided by another manufacturer. He also stated York does not recommend to power this heater and the AHU from the same source and if it is installed that way, it could void the AHU warranty

– even though it is possible to power them together. Drawing M008 indicates to provide a new power cable from the AHU to the electrical panel and mentions a 100 AMP breaker for the AHU, indicating a single point power connection. Are there spare breakers in the electrical panel to power the electric heater separate from the AHU and should this additional power be included in the bid?

Answer 3: That is correct York does not provide Duct heaters. As stated in the project specification, section 1.2, item III (V), the 25 Kw duct heaters should be obtained from Warren Technology or approved equal. Warren Technology is the heater manufacture recommended by York’s Houston Distributor.

Section 1.2, item III (V) of the project specification specifically states that the electric heater shall be powered from spare breakers located in power panel MCH. The new York AHUs will be powered from 100 Amp breakers that power the existing Carrier AHUs.

The statement listed under Note 3 (AHU breaker rating is 100 AMPs) on drawing M008 was provided for contractor information. It was not intended to imply that the electric heaters should be powered from the 100 Amp dedicated AHU breakers.

NOTE: It shall be the contractor’s responsibility to insure that the existing breakers, that will be reused, meet the equipment manufacturer’s requirement for overcurrent protection. If existing breakers do not provide sufficient equipment protection, it shall be the contractor’s responsibility to provide and install appropriately sized breakers.

Question 4: Drawing M008 indicates new smoke detectors. Please confirm fire alarm system interface is not part of the project scope of work.

Answer 4: The new duct smoke detectors, as identified in the project documents, shall be wired into the new OAS HVAC control panel not the facility fire alarm panel. As stated in the project installation documents, the contractor shall be provided with a copy of the OAS controller’s installation/user’s guide. The FAA shall also provide technical guidance on controller installation should it be required. NOTE: There are existing smoke and heat detectors that are wired into the building’s fire alarm system that will remain in place and are not directly tied to the OAS HVAC controller.