Carrier Central Station Air Handling Units (1940s–1979)

Product Description

Carrier Corporation, founded in 1915 and widely recognized as a pioneer in modern air conditioning technology, manufactured central station air handling units for much of the twentieth century. These large-scale systems were designed to condition, filter, and distribute air throughout substantial commercial, industrial, and institutional facilities — including manufacturing plants, hospitals, government buildings, universities, and office complexes.

Central station air handling units differ from smaller, self-contained air conditioning equipment in both scale and complexity. These systems typically occupied dedicated mechanical rooms and incorporated multiple internal components: heating and cooling coils, fans, mixing chambers, filters, dampers, and extensive ductwork connections. Because of their size and the demanding thermal environments in which they operated, manufacturers like Carrier relied on insulating and fire-resistant materials throughout the assembly of these units during the mid-twentieth century.

Carrier’s central station air handling units produced from the 1940s through the late 1970s were widely specified by architects and mechanical engineers for major construction projects throughout the United States and internationally. Their presence in large industrial and commercial buildings meant that many of these units remained in service for decades, creating ongoing maintenance and renovation exposure scenarios well beyond the original installation period.

Asbestos Content

Asbestos was incorporated into Carrier central station air handling units through several pathways common to the HVAC industry during this period. The material’s fire resistance, thermal stability, and insulating properties made it a natural fit for equipment designed to manage large volumes of heated or cooled air under continuous operating conditions.

Insulating materials applied to the interior and exterior of air handling unit housings frequently contained asbestos, particularly in applications where units were located near boilers or other high-heat equipment. Internal lining materials — including blanket insulation and board insulation used to reduce heat transfer and dampen sound — were often manufactured with chrysotile or other asbestos fiber types. Gaskets sealing access panels, flanges, and internal component connections were commonly made from compressed asbestos fiber sheet.

Thermal insulation on heating coil sections and steam connections associated with these units was frequently asbestos-based, consistent with broader industry practices for piping and mechanical insulation of the era. In some configurations, sprayed or troweled asbestos-containing fireproofing materials were applied to structural elements within mechanical rooms housing these units, creating additional exposure sources during service work.

As asbestos regulations tightened through the 1970s — including the Environmental Protection Agency’s early regulatory actions and OSHA’s initial asbestos standard in 1972 — manufacturers progressively moved toward substitute materials. Carrier’s transition away from asbestos-containing components in air handling unit production generally aligned with industry-wide shifts occurring across this decade, with units produced after 1979 reflecting substantially revised material specifications.

How Workers Were Exposed

Industrial workers who installed, maintained, serviced, or removed Carrier central station air handling units during the product’s operational lifespan faced potential asbestos exposure through several documented mechanisms.

Installation crews working on new construction projects handled raw insulating materials applied to unit housings and connected asbestos-insulated ductwork and piping systems. Cutting, fitting, and fastening insulation board or blanket materials generated respirable dust containing asbestos fibers, particularly in enclosed mechanical rooms with limited ventilation.

Sheet metal workers and HVAC mechanics who performed routine maintenance on these systems were required to access internal components by removing and replacing gaskets and insulated access panels. Disturbing aged gasket materials — especially compressed asbestos fiber gaskets that had hardened and become friable with heat cycling — released asbestos fibers into the breathing zone of workers performing this work.

Industrial maintenance workers employed at facilities where Carrier central station units were installed often performed service tasks without specialized respiratory protection, particularly prior to the establishment of OSHA’s asbestos permissible exposure limits. Replacing insulation, cleaning unit interiors, or modifying ductwork connections all presented opportunities for fiber release.

Pipefitters and insulators whose work brought them into proximity with these units — connecting steam or chilled water lines, replacing pipe insulation, or working on associated mechanical systems — faced bystander exposure from disturbed asbestos materials, even when they were not directly working on the air handling unit itself.

Litigation records document that workers in industrial settings often performed these tasks in the presence of other tradespeople, compounding total asbestos exposure from multiple concurrent sources. The cumulative exposure environment of large mechanical rooms — where pipefitting, insulation work, and HVAC maintenance frequently occurred simultaneously — is a recurring theme in occupational asbestos litigation involving air handling equipment.

Documented Product Identification

The following details are drawn from public asbestos litigation records, manufacturer catalog pages, technical manuals, and corporate history materials. Each item reflects the product as documented in those sources.

Documented asbestos-use period: 1922-??

Corporate context: Carrier Corporation, headquartered in Syracuse, N.Y., became a subsidiary of United Technologies Corporation (UTC). The company is also named individually and as a successor to Bryant.

Brand identification: Brand names include: Carrier, Day & Night, Payne, Bryant

Documented asbestos components: packing, gaskets, pre-formed gaskets, coated insulation boards, rope caulking.

Documented asbestos-component suppliers: the public records lists the following external suppliers of asbestos-bearing packing, gaskets, and seals used in conjunction with this manufacturer’s equipment — Durabla.

Industries served: U.S. Navy, Marine, Submarine construction.

Naval / marine service: This manufacturer’s equipment is documented in connection with U.S. Navy and commercial-marine service.

Documented product lines:

• 170 Ton Absorption Refrigeration Machine (1960). Naval shipboard absorption refrigeration system using lithium bromide solution for climate control on submarines. — asbestos components: packing, gaskets.

Carrier absorption refrigeration machines were installed on U.S. Navy FBM submarines including SSB(N) 608-636 class vessels built at Electric Boat Division, Newport News, Mare Island Naval Shipyard, and Portsmouth Naval Shipyard. Asbestos packing was used in diaphragm control valves.