What causes water to always drip from an electric furnace when its turned on?

Question

I made an electric furnace as a university project. It can heat up air inside up to 1000 degrees Celsius. It's not fully sealed so some air can escape from small gaps. Not sure if this would cause a problem or not later on, but water always drips a few times from certain places during operation.

The furnace is encased in a steel plate. I noticed that the top case has a lot of dew (from vapor condensation I assume) once the furnace started to heat up.

• What causes water to drip?
• Is it a dangerous thing?
• If it is, is there a way I can do to prevent it, or at least lessen the frequency?

IDK if this help, I live near the equator and the humidity here is always high.

Edit: added observation and pictures (read from top to bottom)

~5 minutes after successfully reaching 1000 C for the first time I opened this top plate. Its underside is full of condensed water. I noticed steam rising from the top when it reaches ~300C to 1000C. Not much but it's noticeable.

Answer 1

You built it wet

Obviously you used damp materials to build the furnace. Turn it to a low setting and run it until it's dry. It's no more complicated than that.

Answer 2

You need to consider what materials were used in the lining and in the insulation. Some materials can give off a lot of water on heating, without being wet to start with. This is called water of crystallisation

For example, dry plaster of Paris, when heated, will undergo a chemical change and give off water which is bound into the crystal structure. Gypsum plaster is well known for this, which is why I use it as an example. If you've used firebricks this won;t apply as they've already been fired and don't take up water chemically (they may still do so physically if stored somewhere wet).

Glass wool, being made of silica, can hold quite a lot of water physically stuck to the surface.

Of course once the water, whatever the source, gets into the air in the insulation, it will either escape as steam, or condense on the walls and flow out.

Heating alone can't cause condensation, only evaporation, but you have cooling at the walls. However that's cooling to (above) ambient so you can't condense out water that the ambient air can hold.

One other possibility: it's not unknown for furnaces of different types to this to use water-cooling around ports or controllers. Both leaks in the cooling loop and condensation on water-cooled parts could conceivably leads to wetness. But I reckon you'd know about and water-cooling loops and would have told us.