Heat Exchanger RFQ Checklist

1. Define the required duty

State whether the unit will heat, cool, condense or evaporate the working medium. Provide required duty when available, along with entering and leaving temperatures.

• Working medium or refrigerant
• Required heat-transfer duty
• Entering and leaving conditions
• Normal and maximum operating conditions

2. Describe both sides of the exchanger

For an air-side coil, provide airflow and air condition data. For the fluid or refrigerant circuit, provide flow rate and allowable pressure drop when these are design constraints.

• Airflow and ambient or inlet condition
• Fluid or refrigerant flow rate
• Allowable pressure drop
• Flow direction and circuit preference

3. Control the physical interfaces

Attach a drawing or dimensioned sketch showing the maximum envelope, mounting points, connection locations and required service clearances.

• Overall length, width and height
• Connection size, type and orientation
• Mounting holes and frame interfaces
• Tube rows, fin spacing or casing constraints

4. Confirm inspection and delivery scope

List the required material, coating, test method, documentation, packing and order quantity. These items affect the quotation and release plan.

• Material and coating
• Test or inspection requirement
• Required release documents
• Quantity, packing and delivery target

Separate the normal operating point from design limits

List the normal operating point first, then identify any separate minimum, maximum or upset conditions that the quotation must consider. Use consistent units and label whether each temperature, pressure and flow value is measured, calculated or still to be confirmed.

For an air-cooling or dehumidifying coil, ASHRAE selection factors include required capacity, entering air condition, desired leaving condition, coolant temperature and flow, dimensional limits and allowable pressure drops. Treat that list as a completeness check for the RFQ, not as evidence that a proposed product has been rated or certified.

• Normal duty and peak or limit conditions
• Entering and leaving state for both sides
• Flow or airflow with units and measurement basis
• Allowable pressure drop on each controlled side

Compare quotations on the same rating basis

Two capacities are not directly comparable unless the duty, refrigerant or working media, temperatures, airflow or flow rate and rating definitions are aligned. AHRI 420/421 provides standardized rating requirements for specific forced-circulation unit coolers, but its scope does not cover every custom exchanger or replace the project load calculation.

Ask each supplier to state the conditions used for any quoted performance. If one proposal uses a different temperature difference, air condition, fan input or pressure-drop allowance, record the deviation instead of comparing the capacity numbers alone.

Define the supplied equipment boundary

State whether the request covers a heat exchanger core only or also includes headers, frame, casing, fans, controls, supports, drain pan, insulation or other equipment interfaces. Photographs and category names do not establish the contractual supply boundary.

Identify customer-supplied parts and the party responsible for mating dimensions, electrical data and field installation. This makes technical comparison easier and reduces scope changes after a drawing has been prepared.

• Included and excluded components
• Customer-supplied interfaces
• Required inspection and release records
• Packing, identification and quantity

Close open items before production release

Keep a short open-item list for missing or provisional inputs. Unknown values should be marked as open, not silently replaced with assumptions. Record the drawing revision and the agreed operating basis on the quotation or technical schedule.

Before production release, confirm that the approved drawing, material scope, connections, tolerances, inspection requirements and quantity all refer to the same revision. A complete RFQ improves the review, but the approved project documents remain the controlling basis.