garden-addicted wrote in
:


I have been running that heater for a while now and using a min max
thermometer the green house has never dropped below 5 degrees and
hadn't risen above 10 degrees until recently.

So I am confident in the 3kw parasene heater to keep the frost out of
my greenhouse.

We also have an 80ft by 30ft greenhouse and we use commercial heaters
mounted on the ceiling. These are set to 15 degrees and they run until
the temp is about 20 degrees until it turns off and then possibly
doesn't come on until under 15 degrees. If it was to switch on and off
at 15 degrees it would be going on and off all the time.

In fact if its running at 15 degrees I can turn the controller down to
10 degrees before it switches off and then turn it straight back to 15
degrees and it doesn't come back on for a while.

Quality thermostats used in well insulted residential quarters
typically have a 1.0 to 1.6 degree F (.52 to .83 degrees C) on
to off cycle with a built in heat anticipator. Areas with poor
insulation, such as greenhouses, generally have a wider range
and no heat anticipation built into them because a slight
overshoot during the heating part of the cycle is no big deal.