Re: greenhouse-tomatoes: humidity

["Paul A Cross" <charybda@newmex.com>]

greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
Sent by "Paul A Cross" <charybda@newmex.com>.
-

I have the 12" fan and the 12" louver set on two synchonized $20 digital
electrical timers. I calcualted the cubic feet of air in the greenhouse, and
based on the Cubic Feet per Minute (CFM) rating of the fan, I came up with a
number of minutes to run the fan each hour in order to get one air exchange
per hour from dusk to dawn. From dawn to dusk this fan runs continuosly. It's
located up high to push warm air out of the house.

My 30 x 96 house is about 20,000 cubic feet (low ceiling in this gothic arch
house with 2' sidewalls.) The fan is rated 850 CFM. So the fan runs for 23
minutes each hour in a single cycle. This happens regardless of the outside
air temperature. The heater can keep up with the heat loss. I start this fan
for the season when the plants start making too much humidity in the house,
and then I forget about it until I shut the house down for the season in the
fall. Works great.

-Paul

----- Original Message ----- 
From: "Chris Delker" <ccd@netscape.com>
To: <greenhouse-tomatoes@Lists.MsState.Edu>
Sent: Monday, January 22, 2007 7:10 PM
Subject: Re: greenhouse-tomatoes: humidity


> greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
> Sent by "Chris Delker" <ccd@netscape.com>.
> -
>
> Paul,
>
> Do you run your 12" fan continuously, or intermittently depending upon the
> outside temperature?
>
> Thanks,
> Chris Delker
>
> ----- Original Message ----- 
> From: "Paul A Cross" <charybda@newmex.com>
> To: <greenhouse-tomatoes@Lists.MsState.Edu>
> Sent: Monday, January 22, 2007 12:12 AM
> Subject: Re: greenhouse-tomatoes: humidity
>
>
> > greenhouse-tomatoes - an email list for growers of greenhouse tomatoes.
> > Sent by "Paul A Cross" <charybda@newmex.com>.
> > -
> >
> > Be sure there is no standing water in the greenhouse.
> >
> > Do not water plants after mid-afternoon this time of year if possible.
> >
> > Aim for at least one air exchange per hour at night; do this gradually to
> > avoid overloading the heaters and dropping the temp.
> > I use a dedicated 12" exhaust fan for dehumidifying on one end of the
> house
> > and a 12" louver on the other end. The cold air
> > entering has less water in it than the warmer moist air in the greenhouse.
> >
> > Paul
> >
> >
> >   ----- Original Message ----- 
> >   From: chrisharman@bellsouth.net
> >   To: greenhouse
> >   Sent: Sunday, January 21, 2007 4:05 PM
> >   Subject: greenhouse-tomatoes: humidity
> >
> >
> >   Hey,
> >
> >       What is the best way to control, manage and lower humidity in the
> > greenhouse?
> >
> >   Thanks
> >
> >
>