Are box coolers/ electric space heaters any good?

Are box coolers/ electric space heaters any good?

Electric space heaters can be a great way to heat up a small space and can also offer a great alternative to central heating, but they are big electricity users as demonstrated below.


Heater type

Running cost / 500 hours

Small gas (1.5kW)

$212.50

Portable electric heater (2.4kW)

$312.50

Small reverse-cycle air con (3.5kW)

$113.83


If by box cooler you mean a portable cooler like a portable evaporative cooler, they are best for a single room, renters, or temporary situations. They do however only cool a limited space. They are very cheap to run.
Or if you mean a reverse cycle portable air conditioner, they suit spaces ranging in size from dens to garages, provided you have a nearby window through which to vent hot air. 
There are box coolers that fit into an open window and plug into a power point. These could be useful for a single room, renters, or temporary situations. They would cost about $300-$400 per year to run. 
If you mean a permanent cooler that mounts in the wall, the price of these is close to a reverse cycle split system (RCAC) so you would be much better to buy the RCAC and receive heating as well. An RCAC is also more efficient.