The heat output of
multiple High-Intensity Discharge lights can create a considerable problem
for the grower. It may be difficult to keep the heat below 80 degrees
without CO2 or below 95 degrees with CO2, especially in the summer.
Gardeners lucky enough to have a basement grow room will appreciate it
during the heat of August.
There are many solutions to the heat problem. Some are simple but expensive to set up and operate, and others are inventive and inexpensive. Let’s start at the top.
Air Conditioners
Installing an air conditioner is a quick and simple fix for many heat build-up problems. Simply put one in the window, set the vent on closed position so that the CO2 laden air is recycled, and set the thermostat to turn the device on at 95 degrees. Most gardeners don’t seem to mind the cost, considering the benefits. But those monthly electric bills can become real worriers.
Sensible Use of the Air
Conditioner
There are some climates and conditions
where an air conditioner is just about the only way possible to keep the
temperature down to desired levels. Even so, there are a number of
steps that can be taken to keep electrical use to a minimum.
Here are a few of them:
Swamp Coolers
A swamp cooler is a name for an evaporative cooler. This is
a device that cools the air by circulating water over cedar pads and
drawing a high volume of air through the wet pads. The evaporation effect
draws a lot of heat from the air. The problem is that some water is put
into the air.
Swamp coolers work best in dry climates, where they are most
often used in lieu of air conditioning. In dry areas the humidity
occasionally stays down in the teens during the hot months. The cool air
coming from the swamp cooler can be quite low in humidity.
"Broken” Air Conditioner
An air conditioner that has the compressor unit broken or
disconnected can still be of considerable benefit to the grower in a
heat-overload situation.
The warm air of the grow room is
circulated through the cooling fins of the air conditioner’s refrigeration
unit, just as in normal operation but without the compressor operating.
Although the fins are not as cold as when the energy-sucking compressor is
operating, the outside air keeps them much cooler than the grow room air
that is circulating through them, and they remove a good bit of heat from
the air. By operating the conditioner in the unventeun ventedon, no CO2 is
lost to the outside air.
The effectiveness of this method has been demonstrated by a
180 cubic foot growroom running two 1000 watt UPS horizontal lights.
(The ballasts were placed in another room, and did not add to the heat in
the grow room.) Despite location in an arid part of California, only the
air conditioner fan was run. This was during a daylight cycle, in an
upstairs apartment, during the summer months.
Remote Conditioning
The “broken” air conditioner concept can work well in a
situation where the air conditioner is located some distance from the grow
room. In one particular case, the grow chamber was a small cubicle built
against an inside upstairs wall in an apartment. The air conditioner was
placed in the window in the normal manner, and a wooden enclosure was made
for the front of it. Four inch dryer duct hose was used to direct the air
to and from the air conditioner to the grow room, which was about 6 feet
away. The only power supplied was a small squirrel cage fan, which
provided a positive displacement of air through the cooling fins. The
temperature usually dropped about 15 degrees after the air was run through
the cooler.
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