10-gallon Cooler as Primary

I'm thinking of converting a couple 10-gallon water coolers into primary fermenters. I'm planning on drilling a hole into the lid to install an airlock and changing the spigot to one that allows for easier bottling. I feel like this would be a more economical approach for me because I have access to these coolers and I don't need to buy them.

So here's my beginner's question(s).

1. By using a 10 gallon cooler and making a 5 gallon batch that leaves 5 gallons of open space is that good/bad/or doesn't matter for the brewing process?

2. Has anyone else tried this an had success or failure with using a water cooler?

Thanks!

1. Doesn't matter for primary.

2. When it starts to ferment and heat up, how are you going to maintain the temperature since it's insulated?

Are you talking about using something like this? http://mountainhomebrew.com/ProductImages/2177.jpg

If so, thats probably not a good idea. The headspace doesn't really matter in the primary, but I am not sure you can get a tight seal on those, like you do on the plastic pails made for use in brewing.

Also, you can't just drill a hole in the lid and shove an airlock in there. You need to be able to fit a bung for an airtight fit. Otherwise, you should look into the discussion regarding no airlocks on primaries - it's all the rage...

Also, the cooler is insulated, really well. Most people use them as mashtuns for that reason. Temperature control during primary fermentation will be an issue as a result i.e. you will be too high and not know it because those sticker thermometers won't work on an insulated device. So now you have to either geuss at your temperature or drill a second hole in the lid for a temp probe. Wow. What a headache. You should just buy some ale pails instead of trying to reinvent the wheel.

Wow, that does sound like quite the headache. I honestly didn't even think about the insulation factor.

Thanks for the information!

Ale pails are cheap - like $18 with grommeted lid. If your LHBS are nice guys they should throw in a 3 piece airlock for free. And once they seem suspect after somewhere between 5 and 100 brews, you can use them for grain storage if you buy a different lid w/o a hole in it for another $2.

It's nice to know you have coolers available though. If they are new and haven't had gatorade and crap in them, you should start building a mashtun / hot liqueor tun combo like Northern Brewer sells for $250. http://www.northernbrewer.com/brewing/deluxe-ags-10-gallon.html

Edit: The mashtun is a great idea, I have one I made myself. However, you really don't need an entire 10 gallon cooler with ball valve dedicated to simply storing really hot water. But, believe it or not, some people get carried away with their hobbies.

Airtight seal is not important on the primary. Only if you feel the need to watch the pretty bubbles.