Frank Miles wrote:

In article k.net,
Shannon Hughes wrote:
I am planning on building a cold frame that will be either 6 feet by 2 feet
or 4 feet by 2 feet. I would also like to install a solar activated vent
opener on the box. Most commercial units of this size seem to have 2 - 3
lids (vents). Is it possible to have only one vent in the middle that is
about 2 foot by 2 foot in size....is this enough ventilation. My main goal
is to get away with only buying one vent opener.

My 4x4 cold frame has a single vent opener, which raises the entire
lid. The key is the weight that the opener has to lift -- which should
be specified for the opener.

An amazingly high temperature can develop in a cold frame on a sunny day,
so I'd be wary of trying to use a small vent on a large cold frame. I
once baked (killed) some sweet peppers when a vent was improperly re-attached...



a 2 x 2 foot vent should be ok for a 2 x 6 foot cold frame if it opens
wide enough. If the vent is heavy you could try adding a counterweight
on it to make it easier to open.

The vents are not solar activated, but thermally activated. They don't
depend on the sun (except that the sun heats the air in the frame). They
will open on a warm night.