Central A/C Specifications - Warning !
Specifications for Central A/C installations are included for a reason. Please consider the following. The board of directors & property manager should insist that all contractors adhere to the information provided for the following reasons.
* Victorian Condominiums was not built to supply enough electrical capacity for the typical a/c installation.
* Simple & inexpensive modifications are required to soften the electrical load.
An electrical engineer was consulted and performed an on-site survey of Riverside's electrical distribution system. He would not approve central a/c unit installations at Riverside without the following considerations. Note, Victorian is an exact replica of Riverside and built by the same contractor.
1. Systems must not include "heat strip" heat. The electrical load is too great. All systems must be STRAIGHT HEAT PUMPS with no heat strips.
2. All systems must include staggered startup timers to ensure an orderly restart of units in the event of a power outage. The worst case scenario is when there is a 1-second or less power drop. In this event, or brown-out, the compressors that were running at that time cannot restart without a delay and a condition known as "locked rotor" takes place. Thermostats typically introduce a restart delay due to thermostat operation but not due to power drops.
During a compressor start or "locked rotor" event the compressor will draw 5 - 7 times the amount of current causing extreme overloading of the electrical system. Time delay fuses & circuit breakers are used in air conditioning electrical service to all allow for momentary overload until the compressor starts in a normal situation - less than 1 second. In a locked rotor event the 500 - 700 percent overload is continuous until the compressor overheat sensor trips > 10 seconds. The electrical service at Victorian & Riverside cannot survive a locked rotor event from 190+ air conditioners.
Other things to consider.
When apartment complex electrical distribution systems are designed they include a "diversity factor" and a "demand factor". (google electrical diversity and demand) Diversity is an electrical term that allows for intentional under sizing of electrical capacity based on the fact that not everything is all on at one time. Loading evaluation at the Riverside Properties must also account for the use of aluminum wiring. The use history of aluminum wiring requires that loading must not exceed 80% of the wire's rating. That is, a #10 aluminum conductor is rated for 20amps but cannot be loaded to more than 16 amps. Stand alone a/c was not possible at the Riverside Properties until the introduction of high efficiency heat pumps.
3. Additional Parish requirements:
- The parish requires a 2-pole dedicated fused disconnect box adjacent to each roof mounted unit.
- The parish requires a 2-pole dedicated disconnect switch adjacent to each blower unit.
- The parish requires the condensate drain line to be insulated.
- The parish requires a "high water" shut-off float switch in the condensate line to prevent overflow leaking
4. The installer should also review the "Riverside Technician guide" during installation & servicing of the units.
In summary, while it is possible to install some central a/c units without regard to system design without too much malfunction it is not possible to install the units in quantity with no regard. To do so is asking for failure of distribution breakers, service entrance transformers and occasional electrical fires not to mention the increase in demand factor that is such a big ticket item on the power bill.
Installation without regard could cause the parish to condemn central a/c installation at Victorian and subsequently have to remove the installed units simply because good engineering practice as applied to Victorian's electrical system capacity was not followed.
Without the use of orderly pre-approved contractors doing a building at a time there will also be issues of roof leaks from running refrigerant lines and the issue of cutting up a wall in a 2nd floor unit to do an installation in a ground floor unit.