evaporative coolers sizing and installation

Evaporative coolers are rated by the volume of air they deliver, that is, their CFM (Cubic Feet per Minute of air delivered). Most models range from 3,000 to 25,000 CFM.

The CFM is closely related with the number of air changes provided by the evaporative cooler, and many manufacturers recommend units with an air-moving capacity of 20–40 air changes per hour.

Sizing

Improperly sized evaporative coolers may cause high indoor humidity and discomfort.

The size of the evaporative cooler should reflect the area of your home, and specifics of your climate. Installers often use some rough references, when choosing a cooler. Here is a basic one:

- 2 to 3 CFM per square foot, in mild-hot climates;
- 3 to 4 CFM per square foot, in hot desert climates.

Location

Till recently most evaporative coolers were roof-mounted, and many of them still are. But coolers may also be attached to walls, or installed in a shaded area, on the ground.

These last options have some advantages: a shaded area will increase the performance of the cooler, and a non-roof location avoid potential roof leaks and allows an easier maintenance.

Evaporative Coolers, ductwork and diffusers

In some cases the evaporative cooler can use the existing ductwork of the house, if the ducts are sufficiently large (evaporative cooler demand larger ductwork than conventional cooling and heating systems).

Dedicated ductwork is a better solution, but most of the times that isn’t very practical.

Ductless systems

Most evaporative coolers systems are ductless: the fresh air is directly exhausted into a diffuser located in a central room or area of the house and naturally driven from there to the remaining rooms.

This solution works satisfactorily for medium and small houses with rooms opening to each other. In other cases – large houses with multiple rooms not directly connected - ducted systems or multiple evaporative coolers are better solutions.

Cares

Most problems with swamp coolers are caused by improper maintenance (see: Evaporative Cooler Maintenance).

Pay also attention to some basic installing cares. Namely, pay attention to the air inlets location. Air inlets related with evaporative coolers shouldn’t be located near gas flues and plumbing, or exhaust fan vents.