Little thermal mystery (anti-freeze laundry)

[elephant]

I made several small tests, the trend is there: the commissioning of the fan cools the laundry and the cellar is dry: 11 ° and 45% humidity. The laundry itself is dry (like outside air) about 50%

I did not do a lot of testing, because it was very cold and it was really not the time to cool the laundry. On the contrary, the night from Friday to Saturday, I put a radiator (750 W) plugged into a clock.

I will resume testing when it will be less cold: I'm really intrigued.

[the boulle]

Hello

if you inject hot air in a room, that you have a piece not waterproof, (up and down) you will create a chimney effect that will suck the cold air from the outside, and thus in the end lower temperature,

it is a bit like a hot tuyo and a cold tuyo placed in the gel without circulation, the hot tuyo will be frozen before the cold!

solution: to seal the piece (pu foam, door seals, acrylic ...)

[chatelot16]

how long did your trial last?

I am afraid it is too short to be significant: the first effect of your ventilation is to stir the air so to mix the cold air which is at ground level so to lower the temperature ... it is may be longer after you've got the temperature going up

what is your fan? what diameter? what flow?

[Grelinette]

Sorry, my comment was a bit long and off topic.
In order not to pollute this debate I remove it and I create a new subject.

[elephant]

The explanation of the ball is satisfactory: the piece is far from being a paragon of sealing.

To be confirmed by other tests, of course.

[dedeleco]

My laundry room is a simple covered courtyard (corrugated plastic, single glazed door and window, no heating, no insulation)

At the end of the laundry room, a staircase overlooking the boiler room (12 ° in this period of great cold)

I had thought of recovering from the "warmth" the boiler room by sending it to the laundry room using a fan (to prevent the pipes from freezing, of course)

Surprise: in the center of the laundry room: active fan: 4 ° fan cut 6 °

the fan blows air at 11-12 ° towards the stairs.

I do not understand.....

without insulation other than the air of the court more or less still, the T of this air is very very variable from one place to another and often complex by the convection cells between the warmer zones 10 ° C and the soil at about 5 ° C (??) and the cold source at the corrugated plastic ceiling at -10 ° C (even less ??).

Also put a fan, even hot air at the start evenizes the T and depending on where you measure (to specify but far from the ceiling) we will have a more uniform T and therefore colder if measured at 1m from the ground, by faster delivery of the cold ceiling !!!

It is very complex and it is necessary to measure in many places the T and the humidity and the speed and the direction of the drafts !!

There is a little moisture that condenses on very cold plexi sheets and with this dry wind will evaporate and cool, but it is not the strongest effect, except locally where evaporation in a very dry air at present can decrease T of 10 ° C !!
We can also have the opposite condensation of water vapor evaporated from the soil of hot and humid soil to the plexi sheets, which cools the soil and heats the sheets !!

So you have to measure everywhere the T and humidity according to the ventilation to see the changes of the big differences of T.

[elephant]

Excellent analysis. You realize that I'm not going to push further, the concern is simply to prevent machinery and pipes from freezing. Simply my hypothesis of extracting heat from the cellar proved to be inaccurate: the fan is less efficient than the natural escape of hot air (door and window open permanently)

When the danger of freezing will be remote, I will make a comparison: usual situation versus door and window that the cellar closed.

I was left to put a radiator (750W) every night of strong frost between 2 and 6 h to curb the risk.

The owner promised to do some work (replacing the corrugated with double wall polycarbonate, replacing the frame and the door), but, as Kipling said, this is another story

[dedeleco]

If the pipes and machines are against the warm walls on the other side, the simplest is to cover them with old thick fabrics (socks with holes or pierced and worn covers, cardboards or even glass wool) against the wall of the house warm to the interior, the insulators of the air of the cold laundry.
This avoids freezing, even without heating, thanks to the heat of the house that crosses the wall.

Circulating the hot air of the boiler in large ducts or boxes, to the areas to be protected behind old blankets is very effective too.

[elephant]

Alas, the wall is cold.

I thought of putting anti-freeze cord, because I can have it at wholesale price, but my main concern is the machines themselves: there is always water in it.

Anyway, the essence of my question was to understand the process: why it did not work, hence the title: little mystery.

[chatelot16]

if you want to understand, you have to tell us completely what you did! how long did you let the fan run?

the rapid variation of temperature is only a story of mixing the layers of air without a change in the average temperature

if you let the fan run for a whole day, between a room at 18 ° and a room at 6 ° it will end up raising the 6 °

what flow? or at least which fan and what diameter of pipes?