> highest and lowest temps.
I got a digital one at a flower show for 10 GBP ($15) and it works very
well. It's lead is about 5' and it can display Fahrenheit or Celsius. It's
It's external thermometer is not always that reliable and that's the one on
the lead. Sometimes when it is freezing outside and only just above inside
the greenhouse, the external display shows 40'C!!! That's unusual though
and I think it's the bad weather affecting it.
However, if you buy this sort of thermometer I strongly recommend you _do
not_ extend it. If you look at thermometers for commercial glasshouses they
usually have 50 or 100' leads but have their own built in power supply
The instructions on my thermometer explain that if you extend the lead you
will lose accuracy at about 1'C/meter (app. 1.8'F/yard) because there is
only a tiny amount of current going to the thermometer. At 50' long you
would lose about 16'C(30'F) of accuracy. Unless you were measuring _very_
approximately this wouldn't be much good!!
So.... go to a commercial supplier and ask for a out/in/max/min thermometer
with a 50' or whatever lead _built in_ already. Then, any problems and you
can take it straight back.
Also, of course, if you buy a Radio Shack thermometer, and you extend the
lead, you automatically void any warranty the manufacturer offered on the
whole thing, not just the lead.
Hope this helps.