This is a simple and inexpensive incubator for holding samples at or above ambient temperatures. Using the programmable thermostat, temperature can be held constant or programmed to fluctuate diurnally. This incubator is useful for soil samples being baited for Phytophthora species.
The components are available at big box hardware stores and other similar locations:
It will take one person at least several hours to assemble the incubator. The finished chamber is not airtight, as there is some air exchange independent of opening and closing it. We advise use of a min/max thermometer to makes sure the thermostat set points are giving you the desired temperatures. We have found we generally need to be about 3 degrees F lower on the thermostat than our target.
External view of an incubator. Note lid and bottom panel. Holes are cut through the bottom panel for the legs of the wire rack. The power cord fits between the back or side panel and bottom panel.
External view of an incubator showing lid. Note how vinyl drip edge is taped to panels. During construction, first tape all edges of foam insulation that will not have the drip edge applied. Edges with drip edge are sealed when this material is applied.
Vinyl drip edge can be attached two different ways. For the first, shown in this detail, the thin rib of plastic that protrudes from the exposed edge has to be planed away near the velcro closures as shown.
Second way to apply the vinyl drip edge. The thin rib on the short edge is pressed into the foam insulation and does not need to be trimmed away. However, the wide exposed edge of drip edge needs to be trimmed to the width of the panel it will adjoin, at least at the top, so the lid will fit tightly. In our chamber, we trimmed the entire edge for the front panel but only the top for the back panel.
Interior view of incubator with lid removed (next to chamber at right) and front panel open. Rope light is strung beneath each shelf and attached with ties. Both fan and rope light turn on when the temperature in the incubator is below the set point of the thermostat. Note velcro strips attached to side of panel. Corresponding strips are attached to the vinyl drip edge of the front panel. Multiple velcro pieces are used along the length of each panel and corresponding vinyl drip edge to hold the incubator together. Don't use more than three or four short pieces of velcro on the front panel that you will be opening up. On the back and side panels, a few short bits of velcro that attach to the bottom panel will improve stability, but don't put these on the front panel. Note how legs go through bottom panel.
Close-up of LUX thermostat. This is programmable and can be used to have temperature ramp up and down diurnally.
Close-up of incubator fan.