Ventilation of Poly Hives in the winter.

[KES]

I'm wondering how (or if) I should ventilate my polystyrene hive at the top.  I have a screened bottom board with a cover that I can close during the winter but I'm concerned about venting at the top.  Considering the material (very dense styrofoam), I would think it could be very easy to have the mass of bees give off enough heat to create a fair amount of condensation which would rain back down.  What to best way to prevent this or is it even an issue?

Kes

[Michael Bush]

I would make a vent of some kind.  A notch in the cover that would let out the hot moist air would help.  It doesn't have to go straight through to the outside, just making a 3/8" groove from the top and around the corner down so that the air and the bees can get out by going around the corner.

[Robo]

You will definitely need to do something to control the moisture in poly hives.  I've gone with a rigid insulation top with an entrance on mine.



Here are some better pictures.  It is from a double nuc so it shows 2 entrances, but the principle is the same.  I add an entrance tube made out of flashing to keep them from chewing the entrance out.

[buzzbee]

Are the round holes for feeder jars?

[Finsky]

I tell what we do in Finland. I have wintered my bees in polyhives since 1988. Normally bees are in cluster 5-6 months and do not come out at all during hat time. Spring is 2,5 months long after cleansing flight.

I  live on the longitude of Anchorage Alaska, 60 degree.

* In A and B cased you need to restrict first the space of bees that they have not vain cold places where condensation happens.
* Keep hives on the height of 30-40 cm from ground moisture.

A) If you have screened bottom, you need not upper hole to ventilate. All goes via bottom screen. It is purpose to keep screen open whole winter.  Windy site is not good for open hives. Mostly screened bottom are used if hives are in winter shelter or in cellar.

B)
* When you have solid bottom, it needs in back corners one inch holes with screens.
* You need only 100 mm * 6 mm main entrance . Via this mice are not able to go through. Make on closer tips  too small holes ( bee size) to let water come out.
* Then hive hive is slanting forwards that water on bottom comes out.
* Upper entrance in front wall of hive where bees are easy to make flight and returns 10 mm hole is enough.

* Inner cover must have better insulation than walls. Moisture condensates on sidewalls.  If inner cover is colder than walls, moisture condensates  over bees and rains down. You may use breathing inner cover or stryfoam.

Most recommend breathing inner cover over winter and its insulation must be better than sidewalls'

Polyhives need not wrapping in old meaning. But I use in front of hive earth construction textile to prevent snow and wind going inside hive. It helps too that birds cannot catch so easy bees during winter.   

So moisture condensates inside the hive and you may se ice sticks hanging in lower bar of frames. Moisture has swollen food too.

When you open the hive during -10C frost, you see ice crystals here and there, mainly in corners. That is OK.

C) Outer cover

If you have breathing insulation in inner cover, the gap between covers must be well ventilated. If gap is too tight, moisture condensates onto outer cover surface and drops down into insulation.

Robo shows in pictures construction boards but it is too thin for inner cover. If side walls are 30 mm thick, you need 2 boards for inner cover  ( = 40-50 mm) that you get better insulation on top and condensation on sidewalls.

SPRING: Spring is long. It is important for early build up that hive is warm. Good insulation gives back all efforts when hive grows and is able to forage surplus earlier than "normal" hives. What early colony gets, slower cannot get it back later. They just develop later.

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One secret weapon is to put foundation frame against sidewalls before winter feeding.
Don't put pollen frame against the wall.