Last month, I introduced the topic of how decentralized HVAC applications tend to be relatively simple and repetitive equipment/systems that seem to cost more to design than really necessary. This month, I’m going to suggest an “outside the box” approach to producing decentralized HVAC contract documents by eliminating the following traditional documentation and consolidating the information into the contract specification. In regards to repetitive terminal equipment (fan coil units, VAV terminals, fan-powered terminal units, etc.), DO NOT:
- Produce a standard piping detail of the repetitive terminal units
- Produce a standard sheet metal detail of the repetitive terminal units
- Produce an automatic control flow diagram with its associated sequence of operation
- Produce an equipment schedule for the repetitive terminal unit.
Instead of producing the above, consider integrating these four tasks in the contract specification. I’ll use a fan coil unit specification as my equipment example.
Fan Coil Unit
Paragraph 1. Introduction to the terminal unit based on manufacturer no. 1 equipment specification as the basis of design, but including “or equal by manufacturer no. 2 or manufacturer no. 3.” Within this paragraph, specify the construction of the unit enclosure, coil, fan, etc.
In paragraph 2, the design engineer will cut and paste into the specification page the fan coil unit schedule similar to what this engineer would have imported onto a contract document schedule sheet.
In paragraph 3, the design engineer will cut and paste into the specification page the fan coil unit typical piping detail, as well as sheet metal detail if applicable, similar to what this engineer would have imported onto a contract document detail sheet. Also noted will be reference to seismic hanger support for units hung from above.
In paragraph 4, the design engineer will cut and paste into the specification page the fan coil unit typical automatic control flow diagram, including equipment manufacturer’s automatic control details similar to what this engineer would have imported onto a contract document automatic control drawing sheet. In addition, the design engineer will also include the sequence of operation, remote control points, etc., that would have been imported onto the automatic control contract document.
At the end of paragraph 4, the design engineer will cut and paste the commissioning engineer’s or equipment manufacturer’s functional performance test in sync with the automatic control sequence of operation.
In paragraph 5, the design engineer will specify the required equipment startup sheet, troubleshooting sheet, and preventive maintenance workorder tasking and frequency, similar to what this engineer traditionally would have included in the upfront HVAC specification that addressed shop drawings submittal; operation and maintenance manual; list of parts, material, and lubricants; and training.
This approach will end with the design engineer referring to Division 1 for additional information, as well as referring to the electrical drawings for further information on each fan coil unit. Size and quantity of fan coil units will still be shown on the contract drawing floor plans.
So why produce decentralized HVAC system contract documents in this manner? First, it saves time and engineering fees by reducing the number of contract drawings and even eliminates the need for contract drawing schedule sheet(s). For the HVAC contractor, the information detailing the decentralized terminal unit requirements will be specified in a single location so that bidding equipment manufacturers can complete their takeoff using the specification and contract drawing floor plans. No flipping through pages and drawings to make sure all the information has been collected.
For the automatic control contractor and equipment manufacturer, this single location specification will pull together what each control provider requires, and it will also show a complete control system diagram indicating field-installed and programmed versus equipment-furnished and programmed devices and software.
For the HVAC contractor, equipment manufacturer, testing and balancing contractor, and automatic control contractor, all the requirements are located within the terminal unit section of the contract specification, leaving them with only the quantity takeoff from the drawings.
The biggest winner for using this approach will be the facility manager, who will now have all the pertinent information— equipment specification, installation details to assist in servicing the equipment, understanding of the sequence of operation and the training associated with the operation, and the requirements associated with project close-out documents—specified in one section of the HVAC contract documents.
