It reduces heat stress and it is not an air conditioner, which Hessaire says plainly.
Best Spot Cooling in Dry Air Hessaire DC18 Mobile Evaporative Cooler
~$159
A portable evaporative cooler rated at 900 CFM and 300 sq ft of coverage, running from a 115 V adapter or from most major 18 V and 20 V tool battery platforms.
Check price on AmazonSpecifications
| Maximum airflow | 900 CFM |
|---|---|
| Coverage | 300 sq ft |
| Power | 115 V AC adapter included, or 18 V and 20 V tool batteries |
| Battery | Not included |
| Manufacturer's statement | Not an air conditioner, reduces heat stress |
Specifications above come from Hessaire's published specifications for this model. Treat pricing as approximate, since Amazon pricing moves.
What it does well
- Hessaire states plainly that this is not an air conditioner and that it reduces heat stress. That honesty is unusual in this category and it is the correct framing for what evaporative cooling does.
- In genuinely dry air, evaporative cooling is the only cooling that works economically in a glazed structure, because the alternative is refrigeration in a box with a glass roof.
- 900 CFM of air movement is useful in itself, independent of the cooling. Moving air reduces the still saturated leaf boundary layer where fungal disease starts.
- Running from common 18 V and 20 V tool batteries means it works in a greenhouse with no power, which is the situation a lot of allotment and end-of-garden houses are in.
- Portability matters more than it sounds. Wheeling it to the bench that is cooking beats trying to cool 250 sq ft of greenhouse with one machine.
Where it falls short
- It only works in dry air. Evaporative cooling trades humidity for temperature, so in a humid climate it delivers very little cooling and a lot of moisture, which is the wrong direction for a greenhouse in summer.
- It adds water to the air in a structure whose commonest disease problems are caused by too much water in the air. That is a real horticultural cost, not a technicality.
- 300 sq ft of coverage is a rating for a room, not a glazed box under full sun. A greenhouse gains heat far faster than a room does, so treat the figure as optimistic.
- No battery is included, and if you do not already own a compatible tool battery platform that is a meaningful extra cost.
- It is the wrong first purchase. Shade cloth and adequate venting cost less and remove more heat, and a cooler running in an unshaded unvented greenhouse is fighting a losing battle.
What owners report
The consistent finding on evaporative cooling in greenhouses is that climate decides everything. In arid and semi-arid regions growers report real, useful temperature drops. In humid regions the same machines produce a damp draught and very little else. Before buying, check your typical summer afternoon relative humidity: the drier the air, the more evaporative cooling can do, and above roughly 60 percent it has little left to work with. Our evaporative cooler versus shade and venting comparison covers the decision properly.
The second consistent finding is ordering. Growers who install cooling before they have sorted shading and ventilation are disappointed, and growers who shade first find they often do not need the cooler at all. Heat that never enters the structure does not have to be removed, and shade cloth is the cheapest intervention available. Our shade cloth review and the shade cloth calculator cover choosing the right density, which is a bigger decision than most people think.
Third, air movement is doing more of the work than the water is. Even where the evaporative effect is small, 900 CFM across a bench reduces heat stress by breaking the still boundary layer around the leaves. If that is the benefit you are after, a shuttered exhaust fan moves far more air for less money, and our iPower 14 inch shutter fan review covers it. Size your requirement first on the ventilation CFM calculator.
Who it suits
- Growers in arid or semi-arid regions where summer afternoon humidity is genuinely low.
- Anyone who has already shaded and vented the house and still has a heat problem at a specific bench.
- Growers with no mains power who own a compatible tool battery platform.
Who should skip it
- Anyone in a humid climate, where it adds moisture and barely cools.
- Growers who have not yet fitted shade cloth or adequate venting, because those come first and cost less.
- Anyone expecting air conditioning, which the manufacturer explicitly says this is not.
Alternatives worth considering
Do This First rlsclngst 90 Percent Shade Cloth, 20 x 40 ft, with Grommets
~$139
Heat you keep out never has to be removed. Shading is the cheapest and largest single reduction in greenhouse temperature available, and it should precede any cooling purchase.
Check price on Amazon
More Air, Less Money iLIVING 14 in Wall-Mounted Shutter Exhaust Fan with Temperature and Humidity Controls
~$116
1,200 CFM through the wall with a thermostat, for less than this costs. In a humid climate this is simply the better purchase, because exchanging hot air for outside air always works and evaporative cooling does not.
Check price on AmazonBILT HARD 18 in High-Velocity Pedestal Fan, 3,900 CFM
~$70
If the benefit you actually want is air across the crop rather than cooling, a high-velocity fan moves several times the air for half the money and adds no humidity at all.
Check price on AmazonKeep reading
- Evaporative cooler vs shade and venting
- Circulation fan vs exhaust fan
- Ventilation CFM calculator
- Cooling a greenhouse in summer
- 90 percent shade cloth review
- iPower 14 inch shutter fan review
- Best evaporative coolers for greenhouses
This review draws on published specifications, manufacturer figures and the consensus of verified owner reviews. We have not tested this product ourselves, and we say so rather than implying otherwise. As an Amazon Associate we earn from qualifying purchases.