Greenhouse heater settings?

Hey Everyone,

Ive had this heater (3 pin version) set to 6 degrees in my 6x4 greenhouse through winter so far. I've had the thermostat wire resting on 2nd shelf up of my 4 tier shelving. I went to stick more bubble wrap on the roof today as it keeps falling off but noticed that a separate digital thermostat onnthe top shelf near the roof was reading 17.5 degrees!

A lot of smaller plant pots were visibly dry so I've had to water them all.

I've recovered the roof with that reflective roll you can use behind rediators etc that i thought may help a little to hold in the heat (a layer of fleece, bubble wrap and foil in one sheet)

I've now put the thermostat wire on the 3rd shelf up and set it to 5 degrees.

Any ideas of the best way to set this without it clearly being on constantly today? Lol
Am i better to just put the thermostat much higher up and set the greenhouse to something like 10 degrees and hope that any pots on the floor avoid freezing?

Hopefully some if this made some kind of sense.

 

I've been running mine with the thermostat just kicking in around 5°C overnight, seems to do the trick without running constantly. I noticed a huge difference after insulating well and adding a small fan for air movement too. Someone on another forum mentioned using Horizontal Radiators indoors to keep plants going during harsh winters, so that might be another angle if your greenhouse is near power and space allows.