Ok well as can be seen below the chest freezer has been turned into a fermentation chamber, a little bit of tidying to be done yet such as proper blocks and a ceramic heat bulb instead of the 100 watt normal one in there ATM. Anyway i want to stick one of my glass carboys in there that has my cider in from the GB juice buy, still has not cleared after months. How low is safe to chill a glass carboy full of cider ?
ok you need to get one of those 1ft long ceramic heaters and dump the bulb
http://www.ebay.ie/itm/Electric-Tubular-Tube-for-Cat-Dog-Puppy-Outdoor-Kennel-House-Heaters-Greenhouse-/181222688199?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item2a31b6c5c7
You can go down to 0 but don't 5-8 degrees is where you want to be
Have1 degree accuracy and a 10 minute lag on your stc otherwise you compressor will be firing every 5 minutes and will burn out
strap your stc probe to the side of your fermenter when you put in carboy with bubble wrap or insulation to ensure it reads off you carboy rather than freezer air temp.
Quote from: CH on January 31, 2014, 05:28:05 PM
ok you need to get one of those 1ft long ceramic heaters and dump the bulb
http://www.ebay.ie/itm/Electric-Tubular-Tube-for-Cat-Dog-Puppy-Outdoor-Kennel-House-Heaters-Greenhouse-/181222688199?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item2a31b6c5c7
You can go down to 0 but don't 5-8 degrees is where you want to be
Have1 degree accuracy and a 10 minute lag on your stc otherwise you compressor will be firing every 5 minutes and will burn out
strap your stc probe to the side of your fermenter when you put in carboy
Cheers CH, ya the bulb was only for testing purposes anyway. What wattage would i need in my chest freezer in one of them tube heaters ? :D Ok i just measured and the 1 foot 45 watt one will fit on the little shelf in the chest freezer but that's it.
1 have a one ft 60W in the shed in a very tall larder fridge, when the ambient drops to 1-2 outside I supplement with brew belt just dangled as a heat source as it struggles from 1 to potentially 21
if yours is inside lowest its going get is 5-8 so to get 8 up to 18 isn't a big ask
Better to be looking at it than for it (heat that is), put it as low as you can on that shelf. I screwed mine to a board so that I could move it around if required.
http://www.ebay.ie/itm/Electric-Tube-Heaters-1-6-feet-60W-ft-With-Flex-Plug-Brackets-White-/380473804839?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item5896018827
Quote from: CH on January 31, 2014, 05:43:47 PM
1 have a one ft 60W in the shed in a very tall larder fridge, when the ambient drops to 1-2 outside I supplement with brew belt just dangled as a heat source as it struggles from 1 to potentially 21
if yours is inside lowest its going get is 5-8 so to get 8 up to 18 isn't a big ask
Better to be looking at it than for it (heat that is), put it as low as you can on that shelf. I screwed mine to a board so that I could move it around if required.
http://www.ebay.ie/itm/Electric-Tube-Heaters-1-6-feet-60W-ft-With-Flex-Plug-Brackets-White-/380473804839?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item5896018827
Just bought this, thank God for parcel motel is all i will say, the difference between 25.00 euro and 40.00 euro on this one ;D
I've been using a reptile heat mat attached to the sides. Works a treat
Quote from: Simon on January 31, 2014, 07:58:41 PM
I've been using a reptile heat mat attached to the sides. Works a treat
I have a fermwrap which is basically a reptile heat mat Simon but i want to keep that for other thins for now ;D
how bout an old hairdryer? O0
Quote from: Danny(00833827) on January 31, 2014, 09:21:30 PM
how bout an old hairdryer? O0
I see where you are going but it's too much of a risk of overheating with one of those, they run too hot ;)
but your beer would have a beautifully coiffured head on it ^-^
Taping to the side of a glass carboy causes freezer to run more than it needs to. You should leave the probe dangling one you have measured the thermal mass of wort (will be about same for each brew) and the thermal inertia of the freezer. Then set the stc accordingly. The key is to run the freezer as little as possible. By taping to the side of the carboy you will cause freezer to run longer and all you will have achieved to getting the glass down to temperature. The carboy, wort and air temperature will all reach thermal equilibrium over time. You just need to balance the whole system. Also if you bypassed the stat on freezer you have to set stc time for 10 minutes otherwise you will short cycle the compressor. These are only supposed to run 6 times an hour at most.
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It's the temp of the beer you want to change.
Set the dial to max on the freezer and 10 min change on the stc and only click on if 1 degree differential.
Remembering fermentation is exothermic and fermentation temps in first 24hrs are critical if you dangle it or put in water you are going to overrun, equilibrium comes when the thermal mass of the beer is at the set temperature not the air temperature in the compartment, ideally insertion into the beer is best mechanism but never a fan of that for contamination and food approved contact plastic probes. Next best option is with a thermowell or after that attaching to the sides.
Gonna try and show this with a brewPi and 3 probes in the fridge on my next brew.
Not sure you are understanding thermal mass. Plus a freezer will only allow on/off control and not pic. Placing probe in beer or jug of water will not do you much better than causing freezer to run more than it needs to. You are generally only controlling to single point. By right you should be using more than one probe to get readings from various parts of the wort. The problem here is that again the freezer is only on or off. Makes no difference if you are 2degC away from setpoint or 10degc from setpoint you can make the compressor work harder.
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Also glass is a poor conductor of heat so fermentation being exothermic does not make much of a difference.
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The requirement for the freezer part of these cabinets is minimal as if they are in garage it's only lagers in high summer, not ales in mid winter, even inside best not to locate freezer next to the cooker.
Please advise Greg how he can calculate the thermal mass of his wort and thermal inertia of his fridge?
Quote from: CH on February 01, 2014, 12:51:22 AM
The requirement for the freezer part of these cabinets is minimal as if they are in garage it's only lagers in high summer, not ales in mid winter, even inside best not to locate freezer next to the cooker.
Please advise Greg how he can calculate the thermal mass of his wort and thermal inertia of his fridge?
What is best though matters not so much, what is best with what you have is what matters i think. I have the temperature differential set at 10 minutes, as CH knows my chest freezer is in my kitchen away from any heat source, the probe will be taped to the side of the carboy sandwiched between two layers of bubble wrap or directly into the wort depending on what i am brewing.
AFAIK you cant put multiple probes into an stc-1000, if you can then yes i agree 2-3 probes would be great setup. ;D
Quote from: BrewRob on February 01, 2014, 12:41:05 AM
Also glass is a poor conductor of heat so fermentation being exothermic does not make much of a difference.
Glass is a much better conductor of heat than plastics. !!
It is worse than metals!
Quote from: Will_D on February 01, 2014, 10:18:39 AM
Quote from: BrewRob on February 01, 2014, 12:41:05 AM
Also glass is a poor conductor of heat so fermentation being exothermic does not make much of a difference.
Glass is a much better conductor of heat than plastics. !!
It is worse than metals!
Plastic is a good
insulator of heat hence why picnic coolers make great mash tuns etc, glass is a great
conductor of heat hence why glass carboys make good fermentation vessels as the allow the heat to escape and not bake the brew ;D
Quote from: Will_D on February 01, 2014, 10:18:39 AM
Glass is a much better conductor of heat than plastics. !!
It is worse than metals!
Agreed Will the thermal conductivity of glass is 4 times that of plastic. Copper is 400 times the thermal conductivity of glass!!!
That is why I said it is a poor conductor of heat.
Think of all the insulation based materials that are made from glass!!!
Quote from: Greg2013 on February 01, 2014, 10:44:04 AM
Plastic is a good insulator of heat hence why picnic coolers make great mash tuns etc, glass is a great conductor of heat hence why glass carboys make good fermentation vessels as the allow the heat to escape and not bake the brew ;D
I disagree with the Greg. I would not say it is a
great conductor. It is better than plastic but copper is a great conductor. I would still rank glass as being poor.
The important fact about a fermentation chamber is that the ambient temperature is stable.
Air has a really low thermal conductivity 10 times less than plastic.
I just don't see the benefit of putting the probe under an insulator. Like I said it will cause the freezer to run longer. Keeping temperature of the air constant is really all you can hope to achieve with a fermentation chamber. Then naturally the wort/beer will reach thermal equilibrium over time.
Heat given off by fermentation will equalise with the air in the chamber therefore wort temperature drops as air temperature equals until they are both even.
Also just to not if you wish to add extract sensors to the STC-1000 you must arrange them as a wheatstone bridge. You can then connect multiple sensors into one port.
Ok as i said I have seen others do it and am going to come back in a couple of weeks and show you why you need it under a thermal insulator
Comparitively speaking between glass and plastic glass is a great conductor. :P Copper is better of course but out of reach of a lot of home brewers due to price of raw material, unless of course you happen to drive a BMW estate :P
Quote from: Greg2013 on February 01, 2014, 02:45:42 PMunless of course you happen to drive a BMW estate :P
FO its a merc now and you've seen it twice ya blind old git :P
Quote from: CH on February 01, 2014, 02:49:30 PM
Quote from: Greg2013 on February 01, 2014, 02:45:42 PMunless of course you happen to drive a BMW estate :P
FO its a merc now you've seen it twice ya blind old git :P
Sorry i thought that was the wife's car :o
All joking aside though (for now) if not down into a pint glass of water and not down into the wort ( and not up my ass), where and how CH would you setup that probe ? You will have to explain that Wheatstone bridge thing to me next time you are around ;D
Quote from: Greg2013 on February 01, 2014, 02:50:44 PM
Quote from: CH on February 01, 2014, 02:49:30 PM
Quote from: Greg2013 on February 01, 2014, 02:45:42 PMunless of course you happen to drive a BMW estate :P
FO its a merc now you've seen it twice ya blind old git :P
Sorry i thought that was the wife's car :o
............................................... is the sound you hear when the phone hangs up.
Stop trying to confuse me with cryptic answers CH you know my old brain can't handle that kinda pressure :'(
The main reason you place the probe under some insulation, is to dampen the readings for the STC.
The STC is taking continual readings, at a much higher rate than the rate of change of either the air or wort mass reacting to a change in temperature input (either heating tube/bulb or the fridge).
If the wort could react to change of temp as quickly as you made the change, then you could leave the probe anywhere in chamber.
Otherwise as there is a catchup phase for the wort, the STC needs to provide a bit more heat/cooling (over your target temp) to enable wort to change temp and bring it towards your target temp.
In effect you are using the insulation as your correction factor in a manual, non measured PID type effect for your STC.
Hope that's as clear as mud.
An alternative to STC might be an Arduino running multiple probes (air temp, in FV temp, outside FV temp).
Then using Arduino PID sketches you could get that (through relays) to heat, cool & switch a PC fan on/off, when temp differentials between the probes arises.
Really just IF..THEN routines based on what temp tolerances you want to use (obviously stick a time delay on cooling circuit to protect fridge).
Roll on the Brauduino Mk 2.
Or brewPi :)
Oh, You got it up ang working ;)
The STC has a hysteresis band which will account for the dampening effect. Please see my original post.
As a professional automation engineer using a PID loop for on off control is sloppy and does not work. Hysteresis is the gap (effectively) between on/off and PID control. PID control should only be used for continuous output control. In the application of temperature control of wort you woild only use PI.
How it is done generally in the industry is you have a bank of chillers out back bring the temperature of a water/glycol mix fown to about 4DegC. This is then mixed at the jacket eith the return water to eith raise or lower to flow temperature of the jack. There are multiple probes measuring wort temperature. As this is continous control you can use PID. Also at the same yime the supply air is balanced with the rest of the system.
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Quote from: CH on February 01, 2014, 12:51:22 AM
Please advise Greg how he can calculate the thermal mass of his wort and thermal inertia of his fridge?
Ok let's do if your way now please show us how?
You can Google this and get all the formula and information.
Easiest way to get it is by trial and error. Get chamber to known temp. Add water at know temp and known volume and see how long it takes to achieve equilibrium. Do this for a few different temperatures and tabulate the results. Get the average. You must set error limits though as the small the error the longer it will take to achieve equilibrium.
CH how do you calculate your strike water temp if you don't know thermal mass of mash fun and temperature of grain. If you are an extract brewer you need not worry about this.
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(Brewrob: Hysteresis, thanks had been racking brain for that term, long time since I needed it.)
So where do we put the STC probe in the ferment chamber so we don't get temp extremes from, eg tube heating up outside FV air before wort probe reacts, or chamber air temp but fridge cycles too much as - fridge cools, probe tells STC ok & switches fridge off (eg delay 10 mins off), mass of wort still heating surrounding air, probe then tells fridge to cool again, etc).
Or is it we're worried too much about the progressively smaller differential between wort & chamber target temp, that over a couple of hours it balances itself out & will be fine and just have your pitching temp as close to ferment temp as possible when putting into chamber.
In other words your not really going to get funky flavours from high ferment temps if your pitching correctly & then putting into ferment chamber at close to ferment target, ie have good procedures in place to minimise errors.
Strike temp is calculated for me by beersmith and based on grain temp mash tun temp.
I operate herms so I have it very accurate within a minute or so.
I use an ir laser probe to determine wort temp and usually hit it exactly as I prewarm glass carboy.
All this theory is lovely but I'm a practical fella, if anything my ferments have been a degree or 2 too cold, as stated above more likely to trigger the heating rather than cooling
If I use air temp the freezer is gonna be flicking on and off all the time as it chills air quickly and cuts off, heat from fermentor raises temp from an exothermic reaction and ups air temp again and it needs to cool again.
if it's insulated the freezer keeps going until the cool reaches the insulated probe and although the cooling cycle is more aggressive it's less frequent?
@CH your mash is a perfect example.. You don't need to know the thermal mass because your process accounts for it. If you loose 2DegC your process automatically replaces it. Now if you have glycol jacket for your fermenter same thing. You need not directly know the thermal mass, but you pic loop will!! Tuning the loop learns this factor believe it or not.
As far as the heater only home brewers do this. Ask yourself why the "big boys" don't use heaters. You already stated yourself that fermentation is an exothermic reaction so why do you need a heater. Its like installing an AC unit in your sitting room to keep the temperature down. We live in Ireland average outside air temperature all year round is below standard required room temperature. You need heat in the chamber just use the reaction.
I have a temperature strip on the outside of my carboy and also 2 calibrated temperature probes(One NTC one thermocouple). The two probes always read at least 2DegC off the temperature strip when placed in the wort.
What you must remember here is that the fermentation chamber is a homebrew solution (not a professional) one to home brewers problem.
@pob yes I chill to about high 20DegC and drop into chamber at much lower temp. When temp equalizes I can pitch yeast. Remember though using freezer as fermentation chamber the freezer just comes on to try get down to about -20DegC. Water starts to freeze at 4DegC. Have your probe stuck between bubble wrap bad conductor and glass poor conductor can only give a false reading.
I agree with what CH has said earlier that the way he does it is the way he has seen it done. That does not mean it is the right way. However, the equipment is not the right equipment for the job but it is all we have so it must be used the best way it can.
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I have PID but opted for STC with cool and heat. I have fermented at ambient temps recently but will be trying a single input either heat or cool depending on ambient to reach target temps.
I believe with too close a gap, heating may be fighting cooling and vice versa as the heating and cooling sources take time to reach ambient themselves.
Quote from: johnrm on February 02, 2014, 01:05:00 AM
I have PID but opted for STC with cool and heat. I have fermented at ambient temps recently but will be trying a single input either heat or cool depending on ambient to reach target temps.
I believe with too close a gap, heating may be fighting cooling and vice versa as the heating and cooling sources take time to reach ambient themselves.
Once you set the delay to max 10 mins and differential to 1 degree and have a quality fermentation chamber you will be fine and the wort comes up/down to temp it acts like a storage heater and you get less and less input required.
If it's outside you probably won't get any cooling come on at all in this weather.