On 02/04/2014 23:31, David E. Ross wrote:
On 4/2/2014 10:19 AM, nathan984 wrote:
For the past few days its been quite foggy and damp and i walked into
today and the humidity was 99% i opened the window and door to circulate
the air but had to close it after 10 minutes because the temperature
was lowering anyway it lowed the humidity about 5%. I know that the
humidity is to high so i was wondering if there was anything i could do
to lower the humidity like a small computer fan to circulate the air.

A fan will not remove humidity. It will merely circulate the moisture
around the interior of the greenhouse.

Air circulation is far more important that heating (I keep my greenhouse
just frost free - thermostat set at 1°C, and heated with a 1kW fan
heater). Stagnant air leads to mould problems. Remember that alpine
houses have no heating, but keep their windows open as much as possible
to allow air circulation.

I have a small oscillating fan which runs continuously, just being
enough to keep the air moving around the greenhouse. When I started
doing that over 15 years ago, the problem of botrytis and other moulds
on cacti and other dry-region plants dropped dramatically in winter. If
fungal spores cannot settle, they cannot infect. The cost is minimal -
those small fans cost around £10 in the UK, and are surprisingly
reliable. I had one run continuously for over 8 years before it
stopped, and then a drop of oil kept it going for another 4 years. And
they use only 20 or 30w, so they aren't exactly expensive to run.

--

Jeff