Best portable unit:
- Split Hose Unit - not quite as efficient as a proper installed split syst em.
Usable portable unit:
- Dual air circuit - room air in/out, twin 150mm ducts to wall for air IN t o cool the unit and air OUT exhausting heat (preferably foil insulated too) .
These are rare - sometimes portable, more often wall mounted "under window" favoured by small bank branches & accountants offices, and such like.
Useless portable unit:
- Room air exhausted down single 150mm duct, 26-30oC outdoor air pulled int o room to replace it continually undermining its efforts.
- The exhaust blowers are typically 550-900m3/hr centrifugal blowers which means a vast amount of hot outdoor air pulled in, restrict that air and the unit efficiency falls (catch-22).
If you want to use just fans, you need 12" - eg, AirVent AV12s which are 15
00m3/hr and at least 2 of them. Does very little during very hot days, but the minute they can draw some cool air in from somewhere temps will drop ra pidly and take away the heat-soak effect overnight. Basically like USA Whol e House Fans.