Hey guys! I'm in the planning and designing portion of my new snake and rodent rooms. I've searched and I've yet to find a good answer to the question of exhaust for a rodent room.

My rodent room is going to be 7.5' x 12' x 8' ceilings. The closest suggestion I've found for a rodent room exhaust was for a ~500 cfm exhaust fan. However, seeing as that will completely replace the total volume of air in my room in 1.5 minutes, it seems like overkill.

With 500 cfm, I don't imagine it would need to be run very often. However, I would like to use a smaller fan if I could. That would result in smaller pipes and smaller holes. Would 250 cfm work and how often would I need to run it?

Basically, I'm not looking for a fan that will run 24/7, but I'm also not looking for overkill. Having the fan run for a few hours a day to keep the smell tolerable when I walk into the room will be acceptable. I'm setting it up so that as air is exhausted out of the room, fresh air from outside will be pulled in. Therefore, the room itself will be sealed from the rest of the building.

Any thoughts or suggestions are appreciated.

I have a heavy duty exhaust fan hooked up to the light switch in my building. That way, whenever I enter the building and turn on the lights, it kicks on the fan and cuts down on the smell.

There is quite a few aspects to consider with your question...
Is there air conditioning to this space.? If not consider that even though it takes only 1.5 minutes to clear your space with 500cfm and you may think it is not needed, if there is heat and no a.c. you will want to evacuate the heat more often. Say every 10 minutes to insure heat does not build up. Believe me it will make a huge difference.

A vent fan pulls air out of a room four times faster than a fan is able to push it out. In most situations the proper size vent fan should cycle air out or your space within 5 minutes.

(Length x width x height - total volume.)

With your room size you would need 144cfm to exchange the air completely.144cfm will take five full minutes of on time to evacuate completely.

Okay so here is the math so you can do this on your own with future expansion in mind...

7.5 x 12 x 8 = 720cubic feet

Now using a set value. Let's say you want your space to be completely refreshed with new air in about five minutes we will simply take the value of 5...

It looks like this and is really simple...

7.5ft x 12ft x 8ft = 720cubic feet

720cf / 5 as our time value = 144cfm.

Now if you wanted less evac you simply change your time value.

Every 10 minutes would look like this.

7.5 x 12 x 8 = 720cf
720cf/ 10 = 72cfm..

Easy enough???
The biggest thing will be to make sure your inlet air is equal or greater volume than your evac air. This is easily compensated for by making the area for air to pass in, larger than space to exit, yet adequate enough to avoid stale air lingering and stinking up your space.
On another note you can use a stocking from any women's department to cover your inlet and avoid unwanted pest from finding there way in as well. Works like a filter just insure you compensate a few cfm's to make up for filter drag.

Hope I could help...
Peace, J

I think TwistedEvolution comments is just simple and good.

One thing that people most often forget, if you get air out, new air will take place. People forget where that air comes from. You don't want to push the air out, you also want to push air in. Otherwise, the air will start to come from tiny holes in your house/room, walls etc...

You want to have a neutral room, or a little positive, not negative.

Thanks for the input guys. The design calls for 500 cfm going out and 500 cfm coming in, so that's covered. My primary concern is the size of the exhaust and if 500 cfm is really necessary to keep my room comfortable for the rodents as well as for myself.

For example, if I completely replace the air in my room once per hour, will that keep the smell down? What about once every other hour? Will I need to do it once every 30 minutes or maybe even every 15 minutes to keep it tolerable? If I need to do it once per hour, I think a smaller fan will suffice. However, if I need to do it once every fifteen minutes, then the bigger fan will be necessary.

The room will not be air conditioned. I live in southern NC, so it can get hot and humid. I'm aware that because of that, I will likely need to run the exhaust more often, and perhaps even have fans moving air directly over the racks. Heating during the winter isn't going to be a big issue, as it rarely goes below freezing here.

I think I'm going to stick with the 500 cfm exhaust. It might be overkill, but I'd rather have too much exhaust available than not enough.

Here is a little about mine.
It is rack systems set up in my garage. I live in the heart of Florida and it gets hot believe me. We have seen 98f already this year. When I first set up it was cooler and there was less smell and less problems.
As the months went by it slowly got hotter. I noticed fatigue in the breeders and less production. I started getting worried and had to find a way to cut down on the heat but humidity as well.

I purchased a large orbital fan around 20'' didn't know the math till later and what I have is happy awesome over kill. It is mounted to pull air into my attic since I don't have a window in my garage.
Now my temp is around 77-85 average and very tolerable. I had it on a timer but later decided to run evac 24/7 it is highly efficient and the rodents produce readily.

As for your questions to smell there is more variables involved with the amount of run time for the fan.. Most of the info I provided before is for heat concerns. Now that I know there is no a.c. the heat variable has been covered and of less concern now. As for smell only you will be able to know what you consider tolerable. Here is a few things to consider as far as smell goes.

1. How many rodents do you hope to produce weekly? As well what size will they be allowed to grow to before feeding...?

2. How often cleaning will be done of breeding tubs, raise ups, and birthing tubs depending on your system?

3. Type/Species of rodents? I know this seems weird but it applies.

I clean mine weekly about 3 bales of pine if that gives you an idea of bedding. I use regal downs sawdust and chips. Seems to absorb more but is dusty when changing. Holds down scent very well however. Around 3.85 for me a bale. Check around.

The most I have produced is around 200/250 smalls in a week. It varies from time to time. I have some big girls that eat big so sometimes I have a few large but most meet there fate by mediums. When I raised them up till jumbos and so on I had a lot more smell. Bigger rats equals bigger space equals more food and more poop, in turn more stink...

And last but not least species of rat. I know this seems strange but in my experience I have seen many different species being bred as feeders. Personally I breed all Norwegian wood rats that I acquired from a friend stocked up with breeders and every size in the food chain.Hahahaha
However I have a really good friend who breeds Florida citrus rats. He acquired about 500 of them that were bred by U.F. in a study a few years ago. In my opinion my norweigian's stink compared to them. They smell more like a.s.f. but also like your standard lab rats. However the Norwegian topple them in size, they are much larger than most jumbo rats..

Anyway just some things to consider so you aren't caught blind.
Peace, J

Thanks for the thorough responses. At full capacity (which will take several years to reach), I hope to produce anywhere from 100-200 small rats per week and during baby season, a bunch of pinkies through weaners. I probably won't be able to produce enough to feed the entire collection (again, when I reach full capacity), but my goal is to get as much of my collection on frozen/thawed as possible so I can easily supplement what I can't produce.

As far as cleaning, I plan on once a week cleaning. I plan on actually using a cleaner and disinfectant on the tubs instead of just scraping. That should help at least a little bit with the smell factor.

I'll probably only be breeding Norway rats, with maybe a small group of breeding mice for the really picky eaters. I want to avoid mice as much as I can because I know they smell worse than rats and breeding both rats and mice together often ends up with less than optimal mice production.

Again, thanks for all the input.

Hahahaha mice stink something serious. I have one rack of mice and it is the lead culprit in my scent poblems.

I may have misunderstood what you were saying. Did you mean a few years for the rats to be up to full capacity? I can promise you this only takes a few weeks depending on how many breeders you start with. If you were referring to your reptile collection and breeding, sorry for my assumption.

It sounds like you have everything worked out and glad I could help... as for disinfectant it becomes tedious and believe me scraping and just replacing pine is all that is needed.
Again glad I could help and if you run into any problems along the way don't hesitate to hit me up and I will do my best to help. Good luck

Peace, J

I think TwistedEvolution comments is just simple and good.

Thanks

If your rodents will be in there own building not in a garage or spare room I would recommend an attic vent. I have a 8 by 8 right now with an attic vent designed to vent a 3200 Sq foot attic. In the winter i set it on a time in the summer it runs 24/7. On my next rodent room I will run the same vent in the roof but at the bottom of the building I would add in vents to allow the fresh air in the vents and out through the vent in the roof.
I would not try to hit the CFM on the head. I do not see how to much ventilation could hurt. I live in NC as well and run heat in the winter and A/C in the summer for the rats even with the over sized attic vent I have, it is still a strong smell.

i'm in the process of drill a hole in the wall introduce some fresh air in to my rodent room.....only problem is that the wall is about 14 inches thick.....

i can post pics to give you an idea when i get the hole done, hopefully next week.

Pitoon

What kind of timers are you guys using for your exhaust fans? I'm having trouble finding anything to run a fan for 5 minutes or so every hour...

What kind of timers are you guys using for your exhaust fans? I'm having trouble finding anything to run a fan for 5 minutes or so every hour...

Honestly, I would have use some industrial timer for this. Or even a small PLC that I could hook to other stuff as well.
But I suppose there is an easier solution for home.