Thermal imaging the S8 mini greenhouse
Last night I took the opportunity to head out into the yard with a Flir thermal camera to show you how the new S8 (and S16) mini greenhouses work during these cold nights.
It’s 11pm, the outside temperature is currently 4C below zero, and the air temperature inside of the greenhouse is around +5C. The soil temperature of the trays sitting on the heater cables is a few degrees warmer. Nothing’s going to get damaged by cold in here!
For context, the inside of my polytunnel is currently -5C (as reported by the WaterMate Pro irrigation system). Last night I lost a some crops to frost, inside the polytunnel.
I have the WaterMate linked to my home WiFi and the Harvst web app so I can monitor temperature online:
It’s worth noting that this is pretty much the extreme of the operating range. This is how it’s running in a “cold snap”. Average UK winter temperatures are 5-7C, which leads to much warmer normal temperatures inside.
How does the heating work?
Warmth is provided by three 12v temperature-regulated heater cables, running under each shelf. The cables pull more power when they are cold than they do when they are warm, so we don’t give a fixed wattage per cable; however they are in the ball park of 40W each.
To keep the system within reasonable costs, we have a maximum of around 180W continuous power available from the power supply. When the lights are on (especially with the S16 which has many more lights), some of the heat needs to be turned down. The lights also give off warmth, so the net heating effect is about the same.
Fresh air for plant health
The S8 and S16 mini greenhouses also feature forced air ventilation. An exhaust fan pushes humid, stale air out of the greenhouse, with fresh air being drawn in from the base.
The fan will turn on for cooling when the greenhouse gets too hot, and you can also turn “passive mode” on, which runs the fan at a low speed for 10 minutes every hour, to keep the air inside the cabinet fresh and help prevent damping off.
All our mini greenhouses have built-in self watering. Either with a pump and water tank, or through a mains water connection. For most people, this runs on a timer, which you can vary as the season progresses, and as your plants grow and need more water.
As the spring approaches, the weather can swing wildly from cool and overcast, to clear, sunny and warm. The S8 and S16 have a “hot boost” feature in the automatic watering system which helps prevent your young plants from drying out.
Learn more …
Read more about the S8 and S16 on the product pages: