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IPANY 12-28-2012 02:59 PM

Temperature question
 
Yeah so I have a lager kit and an octoberfest kit. Both have yeast for lager and require a temperature of 53-59 degrees. My ambient temp in my garage is 51 degrees. My question is :

If my garage is 51 degrees and the fermentation process gives off heat from the yeast reaction, will the yeast exothermic reaction compensate for the slightly lower temperature in the garage and create the 53 degrees required for the fermentation?

Or does the ambient temp have to be at minimum of 53 degrees?

dcp27 12-28-2012 04:48 PM

they will work perfectly fine at 51F, should be good to around 45F

fall-line 12-28-2012 05:50 PM

Your temps should be just fine for fermenting that batch. Note that lagers and octoberfests also need to be 'lagered' (cold conditioned) for an extended period of time at near freezing temperatures to stay true to the style, but fermenting at your ambient temperatures will get you well on your way to the beer you are after.

As a general tip, you can always look up the ideal fermentation temperature range for the yeast you are using. You didn't specify which yeast strains you are using, but as an example Here are the details for Wyeast 2633 (Octoberfest Lager Blend). You can see that it's ideal range is between 48-58F (fermentation temp).

Happy brewing!

zeg 12-28-2012 07:00 PM

You don't need to worry about things being too cold in your garage. If anything, they may get to be too hot.

The reason is that the heat put off by the fermentation will raise the temp of the beer above the ambient. This won't have any measurable effect on the average air temperature in the garage, so even if you're heating/cooling the garage, the air temperature will stay at 51. To keep the beer at 51, you need to dump the heat into the air, but this happens slowly when the temperature difference is small. Thus, during fermentation, you may well find that the beer is actually 5-10 warmer than the air it's in. (I don't know the exact number here, but those are the sorts of numbers people toss around anecdotally. They seem reasonable.)

To keep the fermentation at a controlled temperature, you need to monitor the beer temperature directly (or more directly, anyway). If you were driving your heater/cooler with a thermometer immersed in the beer, in the ideal case the air temperature would be driven well below the beer temperature you want in order to match the heat loss into the air with the heat production by the yeast.

In your case, you are probably mostly ok since up to about a 7 rise would still be in the optimal range for the yeast. However, it does mean you'll be running the fermentation at a decreasing temperature as fermentation slows. Most people who care about things at this level of detail suggest starting fermentation at the low end, then raising it toward the high end as it slows---this can help keep the yeast active through the end.

So, you'll more than likely get beer, but your conditions won't be optimal. This increases the likelihood of off flavors. You could reduce that risk in a couple of ways. The straightforward (and expensive!) way would be to invest in a temperature control system. The cheaper way would be to swap your yeast for an ale yeast and make a faux-lager. Ale yeasts are generally more forgiving of temperature variations.

Or, you could just roll the dice and see what happens. It's not likely to fail, it'll probably just leave room for improvement in the future.

dcp27 12-28-2012 08:18 PM

Quote:

Originally Posted by zeg (Post 4723007)
In your case, you are probably mostly ok since up to about a 7 rise would still be in the optimal range for the yeast. However, it does mean you'll be running the fermentation at a decreasing temperature as fermentation slows. ... So, you'll more than likely get beer, but your conditions won't be optimal. This increases the likelihood of off flavors.

It's awfully close to optimal conditions. Lagers are not nearly as exothermic as ales. If the garage is at a steady 51F, I'd be surprised if this got over 55F. You won't get any off flavors as its currently situated. you may need to do a diacetyl rest (raise into the 60s for 1-2 days) towards the end of fermentation, but otherwise it should be good til lagering.

lagers however take alot of yeast, so make sure to make a starter (or use 2 packs if dry) if the kit instructions overlooked that. like fall-line mentioned, you'll also need a way to lager it. worst case scenario, this can be done in the bottles once carbonation is complete

zeg 12-29-2012 02:02 AM

Yeah, if I had to bet one way or the other, I'd say he'd be fine. I'd still prefer to be actively regulating before investing the cost and (more importantly) time to put a lager through the pipeline, but it's a question of risk aversity.

+1 on the starter. Check out yeastcalc.org or mrmalty's pitching calculator. It is shocking how much yeast even a moderate gravity lager requires!

Brewsmack 12-29-2012 11:37 PM

Quote:

Originally Posted by zeg
You don't need to worry about things being too cold in your garage. If anything, they may get to be too hot.

The reason is that the heat put off by the fermentation will raise the temp of the beer above the ambient. This won't have any measurable effect on the average air temperature in the garage, so even if you're heating/cooling the garage, the air temperature will stay at 51. To keep the beer at 51, you need to dump the heat into the air, but this happens slowly when the temperature difference is small. Thus, during fermentation, you may well find that the beer is actually 5-10 warmer than the air it's in. (I don't know the exact number here, but those are the sorts of numbers people toss around anecdotally. They seem reasonable.)

To keep the fermentation at a controlled temperature, you need to monitor the beer temperature directly (or more directly, anyway). If you were driving your heater/cooler with a thermometer immersed in the beer, in the ideal case the air temperature would be driven well below the beer temperature you want in order to match the heat loss into the air with the heat production by the yeast.

In your case, you are probably mostly ok since up to about a 7 rise would still be in the optimal range for the yeast. However, it does mean you'll be running the fermentation at a decreasing temperature as fermentation slows. Most people who care about things at this level of detail suggest starting fermentation at the low end, then raising it toward the high end as it slows---this can help keep the yeast active through the end.

So, you'll more than likely get beer, but your conditions won't be optimal. This increases the likelihood of off flavors. You could reduce that risk in a couple of ways. The straightforward (and expensive!) way would be to invest in a temperature control system. The cheaper way would be to swap your yeast for an ale yeast and make a faux-lager. Ale yeasts are generally more forgiving of temperature variations.

Or, you could just roll the dice and see what happens. It's not likely to fail, it'll probably just leave room for improvement in the future.

Any suggestions on a home made temp controlled fridge/freezer?

SterlingHopper 12-30-2012 12:33 AM

The STC-1000 two-stage temperature controller is only $25 (including shipping) on Ebay. SO much cheaper than the Johnson and Ranco, so long as you print out a Celsius to Fahrenheit conversion table.

zeg 12-30-2012 01:53 AM

I went the STC-1000 route myself. It's $25 for the controller, but it's a bare component---it wound up costing about $60 total for a wired box with two outlets, one for heating and one for cooling. If you're reasonably electrically linclined, this is a good way to go. I used the method Revvy describes here (http://www.homebrewtalk.com/f51/stc-1000-wiring-333680/). There's a link to the original creator somewhere in that thread. I built mine without the always-on outlet, and I put a 15A slow-blow fuse on the incoming power.

However, please note that it does involve wiring 120V (or higher in some countries) AC power. This is serious stuff. While it doesn't require great sophistication, it does require care in wiring things correctly. It's possible to make mistakes that give you a working, but potentially lethal, device, so if you've not done your own wiring before, I would strongly urge you to find someone who has some experience to walk you through it.

With that, you can use just about any cooling device---I've used a fridge and a chest freezer---to provide the fermentation chamber. Set the fridge/freezer to max cold and plug it into the cooling outlet on the STC-1000 box. If you think you're going to need to raise the temperature, stick a reptile or seedling heat pad or a small space heater[*] in there, connected to the heating outlet.
[*] Space heaters are potentially dangerous. There are some ceramic space heaters out there that are ok, although they have a lot of power. This is the route I've gone (though I may switch in the near future). If you're using one of these, you have to be careful where you put the thermometer that drives the temperature controller. If you follow the usual advice, which is to tape the thermometer to the side of the fermentor, then insulate it with foam, you are asking for trouble. It will very accurately measure the temperature of the beer, and crank on the heat until that beer reaches the temperature you want. The problem is that this will take a long time, and the heater will be blasting the whole time. This will give you a possibly VERY high air temperature, which can be quite dangerous.

My solution is to untape the thermometer so it measures the air temperature when heating. This won't heat as quickly, but it prevents runaway heating.

Brewsmack 12-30-2012 02:36 PM

Wiring is not an issue for me. Thanks for the great info! Found the stc and gonna go with it


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