Drying boxes - recirculating or exhausted?

[Bobosan]

One of my many work in progress projects is a drying chamber for stars or whatever else can be safely forced air/heat dried. Is it better to exhaust to outside the box or keep recirculating the same internal air? What about use of heat in a recirculating box vs. an exhausted box?

 

Your thoughts, opinions and practical experiences using this type of forced dry system will be appreciated.

[dagabu]

My vote is for exhausting the air.

 

-dag

[Arthur]

Heated works if you are using a compound that sets by a resin curing such as the resorcinol resins. Otherwise a vented chamber works well with the vent part open and a little heat to cause evaporation and air flow..

 

I have heard of a domestic dehumidifier being used to dry and circulate air in a wardrobe sized drying cabinet - with drying times in the sub 6 hours region.

[Shadowcat1969]

I would also vote for exhausting the air.

 

Re-circulating the air within the box will simply keep the humidity in the box higher because it's trapping the evaporated moisture inside.

[Bobosan]

Had a feeling most opinions would be venting the airflow especially since volatile binder solutions evaporating off certain types of star comps would make a very combustible air mixture circulating within the box........but I just had to ask in case somebody has experimented with that process.

 

I plan to install the portable drying box into the mill bunker and then run flexible dryer venting from the heater/blower unit inside the tool shed out to the box. That leads to another question - push the air into the box or pull it out through the top? I have an explosion proof blower unit liberated from a dumpster...and it actually works!

Edited December 23, 2012 by Bobosan

[mikeee]

Almost like a food dehydrator, you want warm air flowing across the items

and the damp air exhausted from the enclosure.

If the heat source is inside the enclosure make sure it is spark proof.

Better/Safer design is to have a heat source external to the drying chamber if possible.

The fan can also be external to the drying chamber using flex duct or sheet metal duct work.

All depends on how much risk you want to assume with the design & components.