# how many vents



## dannyj (Jan 23, 2007)

I cant decide on how many vents to put in a viv im building

Iv just built a 4ft x 2ft x 2ft viv and need put the vents now in

the vents are 70mm ones

should i put in 2 or 4 vents - i was thinking 4 but wondered if that would be too much?


any advice appreciated


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## Pendragon (Dec 8, 2008)

Hi mate,

If it's for a beardie, then I would put 4 across the top, ant 2 at the bottom on the back wall. : victory:

Jay


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## volly (Mar 6, 2009)

I put 4 x 70mm vents in my 4x2x2's.

General rule is 1 vent per foot of viv but some species require more or less depending on what they are.


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## Pendragon (Dec 8, 2008)

volly said:


> I put 4 x 70mm vents in my 4x2x2's.
> 
> General rule is 1 vent per foot of viv but some species require more or less depending on what they are.


Hey mate, 

Where did you get this rule from, and what does it mean?

1 vent per foot? Is that 1 foot length? (this will be 4 foot)

1 vent per foot? Is that 1 square foot of floor space, (this viv will be 8 square feet)?

1 vent per cubic foot? (this viv will be 16 cubic foot) 

How does this rule apply to placement? Top and bottom of viv?

How does this rule take into acount temps in the viv, and ambeint temp of room?

And as you said, different animals require different ventalation, so how does this "1 vent per foot" work with 100s of different species?

Just a thought : victory:

Jay


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## dannyj (Jan 23, 2007)

4 vents in and looking bloody god damn good upto now


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## volly (Mar 6, 2009)

jabba1967 said:


> Hey mate,
> 
> Where did you get this rule from, and what does it mean?
> 
> ...


 
"general rule" - meaning an average/normal rule for standard vivs.

1 vent per foot of viv width - I.E. 4 vents in 4 ft wide viv e.t.c.

OBVIOUSLY certain species need more or less but the "general rule" tends to be 1 vent per foot.


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## Alister (Jun 3, 2009)

I put 6 in when I built mine mate and the temps are spot on...

The way i saw it was you can block them off if there are too many.

Alister


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## Pendragon (Dec 8, 2008)

volly said:


> "general rule" - meaning an average/normal rule for standard vivs.
> 
> 1 vent per foot of viv width - I.E. 4 vents in 4 ft wide viv e.t.c.
> 
> OBVIOUSLY certain species need more or less but the "general rule" tends to be 1 vent per foot.


Ohhh, "general rule", now I get it...Is it the same general rule that "leo's don't need uv", or that "Beardies don't need a water bowl", or that "10% uv tubes work at 12" distance", or that "lizards can't see red"...ect...ect.

The reason I ask, is because as you can see, this forum is full of people who dish out advice as "the general rule", but when asked to explane this rule...Can't.

Welcome to the club :lol2:

Jay


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## volly (Mar 6, 2009)

jabba1967 said:


> Ohhh, "general rule", now I get it...Is it the same general rule that "leo's don't need uv", or that "Beardies don't need a water bowl", or that "10% uv tubes work at 12" distance", or that "lizards can't see red"...ect...ect.
> 
> The reason I ask, is because as you can see, this forum is full of people who dish out advice as "the general rule", but when asked to explane this rule...Can't.
> 
> ...


 
A "general rule" means something that is a standard/general rule of thumb - just an average - a rough guide e.t.c.

And for the purposes of this thread, I do believe that the OP has reached a decision on how many to use and does appear to be happy with it.

dannyj - some pics would be good please, lol

jabba1967 - not sure entirely where you're coming from, but if you want an arguement - you've picked the wrong person.
i don't bite to that and only offer the advice as i see from a vivarium builder's point of view.
never had a complaint so far and if anybody suggests that i'm doing my business the wrong way, then i will happily take on board any constructive criticisms.

however, for now, i will continue to place vents at a ratio of 1 per foot of viv width unless requested by a customer to add more or take some away.

best regards and happy RFUK'ing,

volly


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## haunted-havoc (Aug 6, 2009)

not arguing that vents are bad (as i use them myself) but i find for reps that need low humidity eg beardies/leos, that if you have a 2foot tall viv if you drop the back by 5 cm and cover with mesh you get very good ventilation

by drop i mean









just an alternative to vents


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## cjsnakes (Feb 15, 2009)

thats true acctually the whole of the top of my gecko tank is metal mesh and both my 4ft vivs have the mesh showing in the above pic and i can still get humidity but my three 3ft tanks have 3 vents and seems to be good so i would go with the general rule :2thumb:


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## Pendragon (Dec 8, 2008)

Yup,

It's not just the amount of vents, but the position aswell, i.e. if you only place vents at the top, then hot air "can" get out, but not as freely as when you have vents at the bottom as well. Plus as you say, vents only in the top holds in more humidity.

The reason you want vents top and bottom is "convection". what you want to happen is, as hot air rises and leaves the viv through the top vents, fresh cool air has to be able to get back in, (if it couldn't you could, in theory, create a vacum), without bottom vents this is hard to do, so this will cause a build up of heat, and humidity as the speed the air is rising is too slow. 

Sooo, the problem isn't the size of the viv in a two dimentional sense, but the size of the viv in terms of volume of air you need to "move". Example, if you have a 4x2x2 viv, this is 16 cubic feet of air, but if the viv was 4x2x4, then it would be 32 cubic feet of air. So my logic tells me that one simple rule of one vent per one foot of viv doesn't make sense, as if four vents are all you require for a 4x2x2 using this four foot four vent rule, then how does it work for the viv that is twice as big, but is still only four foot?

I would have thought that there would be a rule of one vent per 4 cubic feet of air, or something, with multipliers for more or less heat, or more or less humidity, also taking in vent size. Something like;


Volume X vents​______________= X number of vents
Heat/humidity



I thought that since Volly built vivs, he might have an "equation" to determin this, I tried asking, but he seems to have got upset, or he does know, but he doesn't want to tell the likes of us his secret.

:lol2: 

Good luck mate

Jay


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## volly (Mar 6, 2009)

jabba1967 said:


> I tried asking, but he seems to have got upset, or he does know, but he doesn't want to tell the likes of us his secret.


 
not at all, but like i said - you've got the wrong person if you want an arguement.


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## haunted-havoc (Aug 6, 2009)

actually what you said about heat was wrong. heat doesnt rise. 

the molecular density of air when hot is lighter than that of cold air. and as the air heats up the cold air displaces the hot air so really people should say cold air sinks not hot air rises.

also heat travels to cold. the cold doesnt not cool the hot. the hot warms the cold and loses thermal energy and thus becomes colder itself

so by this which is true in the world of physics. having vents at the top if perfectally adaquate as the hot air that is displaced to the top of the viv will cool down as its energy is lost heating the air outside of the vents and then sinks creating a drag affect and dragging cool fresh air in, and will sink to the bottom. which in turn pushes the hot air up again and repeating the cycle.

whereas if you have vents at top and bottom this cycle is broken as cool air will constantly be pouring into the bottom of the viv yes increasing the amount of fresh air in the viv but doesnt necesarily help with circulation. as the air as a whole inside the viv will be cooler thus slowing down the circulation effect


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## Pendragon (Dec 8, 2008)

haunted-havoc said:


> actually what you said about heat was wrong. heat doesnt rise.
> 
> the molecular density of air when hot is lighter than that of cold air. and as the air heats up the cold air displaces the hot air so really people should say cold air sinks not hot air rises.
> 
> ...


Hey mate,

Nice theory, this first point (in red) is an interesting one, so what you're saying is that "hot air balloons" don't rise in cooler ambient air, but that some how the cooler air all around suddenly starts falling and some how pushes up the balloon?

This next point (yellow), so what you're saying is that "convector" heaters don't need air vents in the bottom, as the hot air created inside the heater will fall out the top, and some how fresh air will get back in...Even with no vents...Where, how?

And the heater wont over heat? (by the way, DO NOT try blocking the bottom vents on your convector heater at home kids : victory

The last point (purple) we don't want the air to curculate inside the viv, like central heating in your home, we want to get rid of hot air inside the viv, and replace it with cool air from outside, which is what I think you are saying here, but you make it sound like this "isn't" what we want, when it "is" what we want : victory:

So in short, I have know idea why you posted this, as what we want is for hot air to leave the viv, by whatever means, and be replaced by cool air. 

But it's a good discussion, it's got my brain working over time : victory:

Let me know if I've "missed" the point of your post.

Cheers Jay


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## dannyj (Jan 23, 2007)

ha ha your all getting into this thread - entertaining


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## volly (Mar 6, 2009)

Jabba,

I'm out of this thread now - like I said, I don't bite when it comes to arguements on a forum.

However, I just wanted to know if this rings any bells with you?

_"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense."_

Everyone has thier own opinions and ways of doing things and I guess if it works ok for the person in question ( I.E. the OP who started this thread ) - then so be it?

Happy RFUK'ing and I'm sure we'll chat again some day.

Best regards,

Volly


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## haunted-havoc (Aug 6, 2009)

i was trying to say that the cool air enters the viv, sorry if i didnt articualte it that well

i based most of that on GCSE physics that i did way back when. from what i remember from my attepmts to cause havoc in science lessons what i was saying is true

and hot air ballons float on magic and pixie dust. na they fly as hot air is lighter that cool, similar to how helium works as it is less dense than air

sorry if i offended was just my 2 pence, least it got ya thinking however


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## Pendragon (Dec 8, 2008)

haunted-havoc said:


> i was trying to say that the cool air enters the viv, sorry if i didnt articualte it that well
> 
> i based most of that on GCSE physics that i did way back when. from what i remember from my attepmts to cause havoc in science lessons what i was saying is true
> 
> ...


:lol2:

You got me thinking alright : victory:

Cheers Jay


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## Pendragon (Dec 8, 2008)

dannyj said:


> ha ha your all getting into this thread - entertaining


I hope you're taking note, this is all for you :lol2:

The bottom line is, I don't want to see you end up with the same problems as a lot on here get in the summer with Beardie vivs that get too hot.

So I will leave you with these thoughts, then it's up to you : victory:

As far as I am concerned there are 6 distinct environments that most of the herps we keep fall into.

Temperate (moderate humidity)

Sub tropical (low humidity)

Sub tropical (high humidity)

Tropical (low humidity)

Tropical (high humidity)

Desert (low humidity)

Getting a viv that can cope with all these different environments properly is immpossible, so the "typical" viv design you can buy from your typical rep shop will be a "jack of all trades" afair, when if you are building your own, you might as well make it a "master of one" : victory:

So getting back to your viv, the challange you have is, to create a basking temp of around 110f in the hot end, (typicaly placed 12" from one end of the viv), and a cool end of around 80f (typicaly 12" from the other end). So this means you need to loose 30f of heat in a distance of 24", in a closed box. This is a lot harder to do than it sounds.

A tip I will give you is. It is better to have the viv run too cool in the winter, than to run too hot in the summer. You can always get the basking temps right in the winter, but getting rid of unwanted heat in the summer can be a nightmare.

Good luck

Jay


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## mrcarlxx (May 1, 2009)

as its winter i would put three in....and see how it goes, you can always add another one later on


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## dannyj (Jan 23, 2007)

mrcarlxx said:


> as its winter i would put three in....and see how it goes, you can always add another one later on





JABBA - you are indeed right on the last post, iv gone as carl says - iv gone for 4 at the mo and play with the temps, humidity and cooling as i go - if it looks like i will need more - i can soon drill more in

Thanks for the debate and help on this everyone - only time will tell


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## Pendragon (Dec 8, 2008)

dannyj said:


> JABBA - you are indeed right on the last post, iv gone as carl says - iv gone for 4 at the mo and play with the temps, humidity and cooling as i go - if it looks like i will need more - i can soon drill more in
> 
> Thanks for the debate and help on this everyone - only time will tell


Only on the last post!!! :devil:

:lol2:

Good luck mate

Jay


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