Cave: a mystery! Do we have a ghost?

 As you can see we seem to have a ghost in our cellar, and he’s not happy.

Engineer Jansen discovered this by fingering some loose stones, and even taking one out, worried about the state of the wall. To his surprise there was nothing behind the removed stone. More stones were loose, and quickly removed:

It could be the long lost tunnel to Kirrin Island! 

But no, it is not a tunnel. Our cellar has a black hole in it! 

The black is soot, as we soon found out, having it on hands and clothes. 

Soot? From fire? 

Did they have a fire in the cellar? 

Is there a chimney? (No, I think, at least not any more.) 

What on earth do you use a fire in a cellar for? Asked the question in the facebook forum for Spanish Molinos, ACEM - Asociación para la Conservación y Estudio de los Molinos but so far no answer.

As far as I know this cellar was not for storage, but there were parts of the machinery here. Cogs and belts and wheels. Maybe they needed a bit of fire for softening grease for the bearings?

The left gap could well have been the storage space for firewood or even coal:

Perhaps we will never know. 

We decided to not plaster over any weird holes in the cellar (...) and keep them accessible for posterity. The black hole will have a sheet of plexiglass or something.

Cave, but now properly

We wanted to use the cellar under the kitchen for storage of canned and bottled food stuff, and clean up the kitchen. The cellar is about 30 m², which is a quite useful space:

In cellar posts I have written down some experiences with our cellar, and how it was humid, and is now a lot better by removing the old plaster and installing a ventilator. But, it's still not good enough for food storage. Or in fact any storage. The humidity now is reasonable, but the walls and ceiling kept dropping dust and bits of old plaster, covering everything with a nasty dust layer. And, the floor was not a proper tiled floor, but a very old-fashioned compacted earth floor.

What to do. Engineer Jansen learned from Le Bricoleur (Christian von Klösterlein) that you better not simply tile a floor like that, or humidity will rise up in the walls and make things even worse. His solutions always are for ground level floors, and thus he digs in drains and applies external wall cladding to keep moisture out. As this is a cellar we cannot apply external cladding or drains, unless we dig a huge trench. 

We decided that the walls need plastering with the very breathing Kerakoll Muroseco plaster that we already used in the kitchen and cave room with great success: those walls are now properly dry, which is a huge improvement for the atmosphere in the house. A humid house you cannot heat in winter: every bit of warmth is sucked up by the wet walls, and gone. 

But what to do about the floor? Engineer Jansen thought it would be a good idea to build a floor with a ventilatable space underneath:

On top of those beams  ceramic tiles are put, then a layer of concrete, then tiles. And, a proper expansion joint all around the floor: a modern concrete slab in a classic building can be a danger to the house, even though the temperature in the cellar is pretty constant. 

As you can see in the picture above they left gaps between the end of the beams, and underneath the beams too. That was not what was requested, we wanted separate channels, so those gaps are filled with a blob of cement. 

And lo!

At both ends of the cellar there are plastic gutters:

The idea is that the extractor fan at the end of the cellar expels the air down into the second cellar, thus creating a gentle airflow over these grates, hopefully ventilating the floor below enough to not make damp rise up into the walls.

We ordered 8 metal Ikea racks 160x80 cm for storage. Stay tuned! Oh, just heard that it will take 4 weeks to get them delivered, due to the corona crisis. Always something.

Ventilatorderster

In http://jansenendewaal.blogspot.com/2018/09/ventilatorderst.html I wrote:

"Eat that, humidity!"

Well yes. And it works. Only, this ventilator is so strong that you cannot close the cellar door any more. It has two 10x10cm ventilation grilles, but that is not enough. So, the door needed to be slightly ajar, with a rubber bandage to keep it as closed as possible. But, never actually closed.

Worse is that the cellar takes its air from the kitchen, so in the evenings, when the heating is on, a lot of warmth was sucked into the cellar. You could see the curtain flap. Added a timer to switch off the ventilator in the evening and at night. At night too, as you could hear the ventilator drone in the distance, as the cellar door was slightly ajar. But, then, in the morning, you could once again smell the cellar slightly, in the kitchen.

Grmbl.

Decided on a new plan. Now the lowest mill cellar is naturally ventilated again by the grille next to the house and the window in the back of the garage there no longer is an absolute need to force the air from our cellar through there. Closed off the hatch to the lowest mill cellar by putting the hatch with the big ventilator in a plastic bin bag. And, re-installed the 15 Watt 230V ventilator on the pipe that goes outside at the top and back of the cellar.

Now the ventilation opening in the door are big enough, so the door can be properly closed. Attached a plastic bag to each of the ventilation openings, so air can only go into the cellar, and not out.

Slightly more humid (5%) than the kitchen, and the outside air.

Yes, freezer bag and gaffa tape.

Ventilatorderst

The cellar remains humid, despite efforts to ventilate it better, as described in Ventilatorder:

That is a nice Panasonic 14W ventilator, and built to last. But, not enough.

Bought a bigger one, 46W this time, bigger in size, too, so it runs at a lower RPM, and is not very noisy.

Eat that, humidity!

Ventiladorder

In the past, air passed through the lower watermill cellar through the black grille next to the house, and the "door". When the watermill was stopped and the mill reservoir was broken the wind passed through the cellar by the black grill and the water tunnel.

When the workshop was built the back wall closed off that venting, and all humidity ended up in the garage. Apparently no one before realised that the black grill is a ventilation opening.

We tried to mend the humidity situation before, see solar ventilator. That did work well, especially for the atmosphere in the kitchen. However, ventilador 2 in the garage did not work at all. The humidity and volume of air are too great.

We asked Emilio (the builder) to make a nice big hole, where immediately very humid air started to pass, in large volumes.

The solar ventilator passes 60 m3 per hour to the outside, but only when the sun shines. In the evening and in the morning you could smell the cellar a bit, as the ventilation is then halted. We will switch to the grid.

This 230V ventilator has a capacity of 180 m3 per hour, day and night. It moves the air from the first cellar under the kitchen to the watermill cellar, and from there to the new opening in the back of the garage and to the black grille next to the house.

Intention is that no more air flows from cellar to the kitchen, and to dry out the watermill cellar, so the garage stays dry. There is a sheet of plastic between the back of the garage and the garage, so the humid air is forced out through the new window.

It could be the solar ventilator in cellar 1 is no longer necessary, or even that the pipe up and out to the back of the house is better closed off. We'll see (smell).