Thermo cube problem

[jackb]

Our weather has turned cold, really cold. Everything was removed from the greenhouse and brought indoors until the temperatures moderate, about Wednesday. Up until now it has not been cold enough to really use the heater, so the thermo cube had never been tested with the electric fan forced heater. Last night was the first opportunity to really test it and I discovered it has a problem. I have a very accurate remote thermometer and monitored the temperature in the greenhouse, in addition I plugged a small light into the cube to visually see when it was operating. The cube turned the heater off at 35 degrees, and the temperature was below 30 degrees before it turned on again. The heater draws 1300 to 1500 watts, which is within the specifications of the cube. I believe the problem is with heat caused by electrical resistance to the current flowing through the device. The current causes heat to build up within the device itself, so the device reacts to its own internal temperature, rather than the actual temperature of the environment. Tonight I plan to try an electric oil filled radiator with the setting at 900 watts to reduce the load on the device, this may, or may not, solve the problem. The problem is: it takes quite sometime before these heaters warm up. An email has been sent to the vendor who sold the device asking about warranty, but I have not heard anything back from them.

 

[Circle-M-Farm]

Good thing the plants wasn't in the greenhouse.
If your looking for a thermostat, I use a J&D single stage thermostat and haven't had a problem.
http://www.greenhousemegastore.com/product/jd-single-stage-thermostat/s

 

[jackb]

Thanks for the information, I spoke with a tech from the manufacturer and they are sending a replacement unit at no cost. They think the unit may have the wrong thermostat installed. All is well that ends well.
We will see how this goes.
jack

 

[Nyboy]

Got to love a company with good customer service

 

[jackb]

Well, I tested a second cube last night and again it was a dismal failure. They seem to work with just a small load of a watt or so, however when I plugged the heater in the cube switches off in a few minutes, and stays off. I have tried two cubes, with four heater settings: 600 watts, 900 watts, 1300 watts and 1500 watts, the same thing happened with every load. With the heater plugged into the cube the temperature got below freezing and the cube did not activate, so I unplugged the heater. With just the small LED light plugged in, the cube activated several times during the night. When I plugged the heater back in in the morning, the cube again turned off within a few minutes. Had I had plants in the greenhouse, it would have been a disaster, as the temperature hit 18 degrees in the greenhouse last night. The photos below show the greenhouse this morning with the lights on, cube working, and the temperature well below freezing. The second photo was taken shortly after plugging the heater in, the lights show that the cube and heater are off. The cubes have been returned for a refund.
I advise anyone planning on using these for a greenhouse to test thoroughly before trusting the device. I have returned to using what has worked for years: the oil filled radiator and mechanical timer. Moral of the story: don't mess with success.
jack