11 replies to this topic

[shmgeggie]

If you look at historic averages, the average high temp in Spokane is below 50F for 5 months out of the year. It seems like I should be able to build a pretty simple insulated box with a computer fan to keep fermentation temps at about 50F. It would have to monitor temp inside the box and outside the box. If temps were too high inside and low enough outside, the fan would switch on for cooling. If temps dropped too low inside the box, a heater would switch on. How hard would it be to build something like this? I'd only be controlling a small DC fan and maybe one of those ceramic aquarium heaters.

[Recklessdeck]

If you look at historic averages, the average high temp in Spokane is below 50F for 5 months out of the year. It seems like I should be able to build a pretty simple insulated box with a computer fan to keep fermentation temps at about 50F. It would have to monitor temp inside the box and outside the box. If temps were too high inside and low enough outside, the fan would switch on for cooling. If temps dropped too low inside the box, a heater would switch on. How hard would it be to build something like this? I'd only be controlling a small DC fan and maybe one of those ceramic aquarium heaters.

I have never built it but many have. Son of fermentation chiller

[3rd party JKor]

You need two control loops, or a controller with an alarm relay. The main control loop will control the fan on/off, the alarm or second control loop will disable the fan circuit if the outside temp is >50F. With good enough insulation you can probably maintain 50F in your chamber for a majority of the year, but part of the year the fan will only run at night.

[Deerslyr]

If you look at historic averages, the average high temp in Spokane is below 50F for 5 months out of the year. It seems like I should be able to build a pretty simple insulated box with a computer fan to keep fermentation temps at about 50F. It would have to monitor temp inside the box and outside the box. If temps were too high inside and low enough outside, the fan would switch on for cooling. If temps dropped too low inside the box, a heater would switch on. How hard would it be to build something like this? I'd only be controlling a small DC fan and maybe one of those ceramic aquarium heaters.

Interesting proposition. Having spent a formidable time of my youth growing up in Spokane, I question the sanity because of the wide variation in temps. yes, 50 degree average may be right, but that factors in the highs and lows which can be extreme. What months have an average of 50? I think you could do something like this around that time of the year, but if it's during a time of year that has potential for wide variations, I'd question whether the system could keep up with the changes quick enough. Why not buy at $60 cube fridge from Wal-Mart and build a fermentation chamber? Or build the one Recklessdeck linked to. You would have more control in the end and not be subject to the varying wild weather of the Inland Northwest.Just my $0.02.

[Noontime]

I'd have to agree with deerslyr that it would probably be easier to make a controlled environment instead of trying to compensate for an uncontrolled one. However...the first thing I thought of when you mentioned this was an environmental enclosure. Many pieces of electronic equipment are outside in different environments (like camers, communication devices, etc) and must remain in a temperature range. Thery have fans and heaters and thermisters to regulate the temp. You might be able to find a cheap or used one somewhere to use for parts, or at least use information about them as a model.Just a thought.

[stellarbrew]

The control scheme for this type of system would be identical to what you would use to control a lagering fridge, except instead of switching on and off power to the fridge, you'd be switching on and off power to the fan. As cheap as used refrigerators can be had from craigslist (frequently as low as $50), I would recommend going that route. It gives you much tighter control over fermentation temp, and will work even on the hottest day. Plus you have the advantage of being able to set colder temperatures for lagering or cold conditioning, should that ever be your desire. If you frequently have mild ambient temperatures in your locale, you will still benefit from them using the fridge, because the fridge will not need to run as long or as often to hold your required temperature, as it would in a hot environment.

Edited by stellarbrew, 10 June 2009 - 02:48 PM.

[3rd party JKor]

The control scheme for this type of system would be identical to what you would use to control a lagering fridge, except instead of switching on and off power to the fridge, you'd be switching on and off power to the fan. As cheap as used refrigerators can be had from craigslist (frequently as low as $50), I would recommend going that route. It gives you much tighter control over fermentation temp, and will work even on the hottest day. Plus you have the advantage of being able to set colder temperatures for lagering or cold conditioning, should that ever be your desire. If you frequently have mild ambient temperatures in your locale, you will still benefit from them using the fridge, because the fridge will not need to run as long or as often to hold your required temperature, as it would in a hot environment.

Actually, it's more complex than a standard lagering fridge, because you have two possible temperature situations. >50F and <50F. In a lagering freezer you just have a limitless supply of 20F.

[stellarbrew]

Actually, it's more complex than a standard lagering fridge, because you have two possible temperature situations. >50F and <50F. In a lagering freezer you just have a limitless supply of 20F.

That's true, good point, you wouldn't want to circulate ambient air through your box if the temperature of the ambient air is greater than your set-point. Before turning on the fan you would want to meet two conditions: 1. The temperature inside the box is above the set-point, and 2. The temperature of the ambient air is less than or equal your set-point.... Unless the temperature of the ambient air is below the temperature inside the box, even though it may be above the set-point - in that case you would probably want to turn the fan on anyway, to cool the box down to ambient temperature.This would require two temperature sensors: one for inside the box, and one for outside the box. Many controllers only allow for one sensor input. This is another point in favor of using a fridge instead.

[3rd party JKor]

That's true, good point, you wouldn't want to circulate ambient air through your box if the temperature of the ambient air is greater than your set-point. Before turning on the fan you would want to meet two conditions: 1. The temperature inside the box is above the set-point, and 2. The temperature of the ambient air is less than or equal your set-point.... Unless the temperature of the ambient air is below the temperature inside the box, even though it may be above the set-point - in that case you would probably want to turn the fan on anyway, to cool the box down to ambient temperature.This would require two temperature sensors: one for inside the box, and one for outside the box. Many controllers only allow for one sensor input. This is another point in favor of using a fridge instead.

Right. There are some controllers out there that can handle it, but yeah, using the fridge is probably easier.

[Yeasty Boy]

ok, so my thoughts on this - you can quote me on this - are as follows:Bahh.If you have ~50° temps, chill to the low range of your yeast (say 48° if you don't know), pitch and put the carboy in a large tub of water, and leave it in the coolest part of your house (down low, away from heater vents, etc.) Then put a 50w aquarium heater in - for like $10 or whatever - and call it good. The heater will keep it from getting into the mid-40's, and should it get even into the mid-50's it'll still be lager. 56-58° is kinda the high end for lagers, so if you figure on 2-3° warming from fermentation, keeping the ambient at 50 should do great.Way too many homebrewers out there not making excellent lagers simply because they think they don't have (and can't afford) the equipment.

[shmgeggie]

The control scheme for this type of system would be identical to what you would use to control a lagering fridge, except instead of switching on and off power to the fridge, you'd be switching on and off power to the fan. As cheap as used refrigerators can be had from craigslist (frequently as low as $50), I would recommend going that route. It gives you much tighter control over fermentation temp, and will work even on the hottest day. Plus you have the advantage of being able to set colder temperatures for lagering or cold conditioning, should that ever be your desire. If you frequently have mild ambient temperatures in your locale, you will still benefit from them using the fridge, because the fridge will not need to run as long or as often to hold your required temperature, as it would in a hot environment.

I was under the impression that cheap used fridges are not nearly the bargain they seem to be, because they are power hogs, and you'll end up spending more in the long run than you would buying a new energy efficient chest freezer.

[stellarbrew]

I was under the impression that cheap used fridges are not nearly the bargain they seem to be, because they are power hogs, and you'll end up spending more in the long run than you would buying a new energy efficient chest freezer.

It depends on how old the fridge is that you acquire. Mine was built in the 90's, I got it for free, and it isn't all that inefficient. If you buy a 1960's model, it's low level of efficiency might cause you to break even with the cost of a new low end freezer, plus the freezer's operating costs, in about two to three years.