iann wrote:1kW/2kW switchable heaters are cheap and easy to find but the thermostats are not the best. Also, many thermostats either aren't very accurate below zero or simply don't go that low. You might want to experiment and then see if you need to buy a separate thermostat.
The 2kW fan-heaters I have looked at seem to have a "frost-free" setting of (nominally) 5degC as their minimum: is this typical?
Does anyone have a specific fan-heater model they can recommend from personal experinece as having a well-calibrated in-built thermostat which goes down to zero (or below)?
Presumably, to use a separate thermostat without serious re-wiring of the heater, one would use the external thermostat as a cut-off device - i.e. the fan-heater would be plugged into a control box rather than directly into the mains? Does anyone know a good source for such a control box?
My own plan was to move the family to sleep out in the greenhouse in the coldest weather: can anyone tell me the rough heat-generating ability for me and an annoyed wife? (I think the kids will stay inside...)
Yours, Euan
Euan Arnott (Cheshire, UK)
Novice grower renewing his teenage enthusiasm. Rapidly burgeoning Lithops, Lophophora, and Ferocactus populations, plus a few old stalwarts which have acompanied me through the years!
The trouble is that by their use fan heaters make their own components warm , so you are better off with an independent thermostat . the recent very low temps will have tested most set- ups as few will have enough capacity to cope with them.
I had a thermostat failure in winter 2000 which decimated my collection at that time, aggravated because I was working away from home, and so didn't discover it until 2 weeks afterwards. I then invested in fan heaters with separate digital thermostats, with a hysteresis of 0.5C. They appear to have worked fine so far this winter, which has certainly tested them fully. I also bought a 4KW butane heater which I use only as a back up as and when, but so far never needed. I know this sound soverkill, but then I now have a lot of plants.
If you need to heat your greenhouse because of what you lke to grow, then consider the value of the plants (monetary and sentimental) and compare that to the costs of accurate and reliable equipment spread over many years.
Did the separate thermostats come with the heaters Chris? If not, what type did you buy?
I use an Autoheat heater and whilst the in-built bi-metalic thermostat is accurate enough, I like the idea of a separate digital one. Also, having stored the heater unused for 18 months, I found that I had to set the thermostat at '10' to maintain 5 degrees C, whereas last time I used it I set it to '4' !!!? Something's clearly changed with it and I wonder if it was how it was stored i.e. whether I should have turned it to 0 or full up to 12 on the setting dial for storage?. Any ideas?
Thanks
Ross
Ross
Dunbar, SE Scotland.
BCSS member #46264 (originally joined 1983).
Growing cacti since 1978, with a particular interest in Sulcorebutia and Rebutia.
Ross M wrote: Something's clearly changed with it and I wonder if it was how it was stored i.e. whether I should have turned it to 0 or full up to 12 on the setting dial for storage?. Any ideas?
Thanks
Ross
The difference could be due to a slight change in the environment - i.e. it's now getting more heat reflected back from a nearby obstacle or perhaps it's now getting a cool draft from behind.
Zone 8 Representative (Birmingham, High Wycombe, Kingston-on-Thames, Oxford, Reading & Basingstoke, Woking).
For heating 200m2 of greenhouse in my garden and 2 houses i use one wood powered heater, 80kw/h.For now the heater is too strong, but i can increase greenhouse's size at about 400m and then will be just fine. Last night we had -17 celsius and in my greenhouse were 6 celsius this morning ( and i have few radiators).
I am a bit old fashioned- I use Valor Blue flame parrafin heaters burning the low sulphur odour free parrafin.
One has twin burners of a type produced for the military in the 1970's, robust with auto cut off if it gets knocked over. Two weeks ago it went down to -16 degrees ouside and the twin burners kept the inside of the greenhouse at a minimum of 7 degrees. I also have a single burner blue flame of the type that was very common in the 60's & 70's thats a back up but it also came in handy three weeks ago when our central heating packed up.
No need to worry about power cuts but it is messy triming wicks and constantly filling the tanks ups. I keep around 30 gallons in storage in my brick garage. Too old now to change my ways I think the parrafin heaters will see me out.
