Predictive Maintenance Programs (PMP's) In Small HVAC Applications: Analysis of Available Products and Technology

Maintenance of HVAC&R systems and scheduled replacement of components to avoid costly down time, degraded comfort conditions, or health hazards is not new. In fact, designs have not changed dramatically in many years. However, new regulations placed on CFC emissions and other environmental and energy conservation concerns are causing changes. On the traditional side of things, cost for down time for any HVAC&R system whether it be for an industrial process or commercial function can add up very quickly and often results in thousands of dollars worth of spoiled goods or uncomfortable customers, tenants or employees. Even the slightest deviation from the operational norm of the refrigeration system can result in spoiled goods. It is also worth mentioning lost revenue in sales or productivity and even the possibility of coming under a civil suit in situations where HVAC systems go down in occupied buildings. Obviously, avoiding such situations would be desirable to say the very least. In the past, this has been accomplished by what is known as preventative maintenance. In the past preventative maintenance programs have been the only means by which a company could avoid the costly alternatives listed above. The thing is, these scheduled maintenance programs can also be very expensive. They too, often require a certain amount of downtime and unfortunately don't always prevent untimely failures. Many man hours of maintenance time, down time, and inefficient system operation could be avoided with the help of a relatively new method of maintenance called predictive maintenance. With computers getting smaller and more efficient and the electronics involved in monitoring systems becoming generally less expensive, predictive maintenance is coming within reach to industry as well as the private sector. Someone said, "An ounce of planning is worth a pound of work." If HVAC&R systems could be economically monitored and their operation predicted in a literal sense, then many dollars worth of unnecessary maintenance cost as well as down time could be prevented. This paper offers an overview of predictive maintenance technologies available. With the exception of the considerably more complex and expensive control type systems (e.g. the AKCESS 25 from Danfoss), all of the predictive maintanence systems presented here basically rely on comparative temperature measurements. The list of PMP's presented here is not to be considered exhaustive. EXISTING PRODUCTS