Natural (gravity) air soil venting on cold stores (-25ºc)

[Sandro Baptista]

Guys I'd like to get some drawings about the heating soil to prevent freezing by natural air convection. I have 1 of them but I don't agree with the air sense indicated on it...I think that the inlet of air should be at the higher air tube (2,5 m) and the lower tube (0,5 m) should be the outlet (considering that both are at the same exterior temperature).

Awaiting your news

Regards

[Sandro Baptista]

Guys I'd like to get some drawings about the heating soil to prevent freezing by natural air convection. I have 1 of them but I don't agree with the air sense indicated on it...I think that the inlet of air should be at the higher air tube (2,5 m) and the lower tube (0,5 m) should be the outlet (considering that both are at the same exterior temperature).

Awaiting your news

Regards


Sorry the insistence :o

[stufus]

Hey Sandro
I'm not too sure if this is the ASV your referring to but have a look at these.
http://www.google.ie/images?hl=en&rlz=1C1DVCB_enIE332IE367&q=air+soil+venting+diagram&um=1&ie=UTF-8&source=univ&sa=X&ei=NLReTev7B8e6hAfPvvmcCg&ved=0CCoQsAQ&biw=1066&bih=590
All the best
Cheers
Stu

[Sandro Baptista]

Hey Sandro
I'm not too sure if this is the ASV your referring to but have a look at these.
http://www.google.ie/images?hl=en&rlz=1C1DVCB_enIE332IE367&q=air+soil+venting+diagram&um=1&ie=UTF-8&source=univ&sa=X&ei=NLReTev7B8e6hAfPvvmcCg&ved=0CCoQsAQ&biw=1066&bih=590
All the best
Cheers
Stu

Thanks stufus, I have to say I get lost with so different pictures. I couldn't find what I looking for:

» I'd like to get a diagram with venting pipes or "concrete ducts" underneath the floor insulation of a cold store negative temperature so to prevent the freezing of soil by natural air convection. As you should know a main inlet tube is used and a main outlet tube is used. The several pipes that run inside the cold store are connected in parallel to those main tubes.
One of the main tube is elevated (+2,0m as example) and the other is at (+0,5m as example). Supposing that both the main tube are subjects to the same exterior temperature (higher than the cold store soil temperature) and pressure I think the air should out by the lower main tube and enters by the higher tube. However I've see an diagram where the air sense is reversed.

What's your opinion? Do you have any any diagram that testify what I mentioned?

[Peter_1]

I've seen it twice with very, very bad results (condense building up in the tubes and finally resulting in a good isolator)
Pictures already posted in the past here on RE.
They installed a tube that went even higher than the roof so that a natural convection took place.
Air under the soil should be colder then ambient.
How the flow will be? Difficult to predict: will depend on conditions outside/conditions soil, wind direction and speed around the building creating a negative or a positive pressure.
I should never do this again, radiant heating is safer, cheaper and better, in fact perfect controllable.
If you want to install an air net, Install tubes and connect it all to a fan so that air can be forced through it.

[Josip]

Hi, Sandro :)


Guys I'd like to get some drawings about the heating soil to prevent freezing by natural air convection. I have 1 of them but I don't agree with the air sense indicated on it...I think that the inlet of air should be at the higher air tube (2,5 m) and the lower tube (0,5 m) should be the outlet (considering that both are at the same exterior temperature).

Awaiting your news

Regards



Attached you can see similar installation for one cold store installed in the year 2004.... simple, but so far I do not know if they faced some problems later on ... I assume not ...

Cold air is more dry thus heavier and by gravity going out within sloped tube causing "under pressure" at intake so the fresh air is coming in ... natural flow ...


6390


Best regards, Josip :)

[Sandro Baptista]

Hi, Sandro :)





Attached you can see similar installation for one cold store installed in the year 2004.... simple, but so far I do not know if they faced some problems later on ... I assume not ...

Cold air is more dry thus heavier and by gravity going out within sloped tube causing "under pressure" at intake so the fresh air is coming in ... natural flow ...


6390

Best regards, Josip :)

So, for the same outside conditions the air would enter at the higher tube and outs at the lower tube, right?
The slope have the main purpose of draining water from the moisture condensation. If no slope exists it would have exist natural convection at the same.

Thanks a lot Josip

[stufus]

Thanks stufus, I have to say I get lost with so different pictures. I couldn't find what I looking for:

» I'd like to get a diagram with venting pipes or "concrete ducts" underneath the floor insulation of a cold store negative temperature so to prevent the freezing of soil by natural air convection. As you should know a main inlet tube is used and a main outlet tube is used. The several pipes that run inside the cold store are connected in parallel to those main tubes.
One of the main tube is elevated (+2,0m as example) and the other is at (+0,5m as example). Supposing that both the main tube are subjects to the same exterior temperature (higher than the cold store soil temperature) and pressure I think the air should out by the lower main tube and enters by the higher tube. However I've see an diagram where the air sense is reversed.

What's your opinion? Do you have any any diagram that testify what I mentioned?
To be honest Sandro my opinion wouldn't be worth much as what i know about ASV could be written on the back of a postage stamp.:o
I have discussed with others and made the decision it's not for me ,I'm not aware of it ever having been implemented in cold store applications in Ireland.(I could be wrong)
So I'll stick to what i know (which isn't much):D
Cheers
Stu

[Sandro Baptista]

file:///C:/TEMP/moz-screenshot.png6408

Hi guys,

Continuing this "boring" subject :) do you think this is right? That's all this about to get a schematic with opposite sense of the air.

I could go to see one natural circulating system to prove it if I knew some.

[Sandro Baptista]

Please send me your ideas/comments.

[Peter_1]

I don't see why you want it to do this way if a radiant heating is
cheaper,
safer,
works better,
better controllable,
installs faster,
...
Why taking risks with something which can never be adjusted, adapted nor repaired in the future? If this fails, then you have to demolish the whole freezer !

[Sandro Baptista]

The Client wants like that way with air...

[Peter_1]

Ok, his choice then.But I may hope you advised and warned him correctly.

[Sandro Baptista]

About the sense of the air on the doc1.jpg I have sent previous do you have any comment?