Technical Committee 1.7, Durability, Reliability and Serviceability, has been attempting since 1972, to establish some criteria and guidelines in the reliability/maintainability area for heating, ventilating and air-conditioning equipment. We were able to define several terms which now appear or will appear in Chapter 42, Operation and Maintenance, of ASHRAE Handbook & Product Director. However, our attempts to establish some definitive numbers which can be expected in the maintenance area have met with frustration.

We found that manufacturers and users do not necessarily know or keep track of things like preventive maintenance costs, corrective maintenance costs, mean time to repair (MTTR) equipment, nor mean time between failures (MTBF) of equipment. This paper will show how one user organization is now collecting maintenance costs and hopefully will be the impetus for further involvement of others in establishing maintenance costs, maintainability/reliability criteria, and guidelines for manufacturers and owners.