Cool Room and fermentation Air Conditioning

[wide eyed and legless]

I finished my cool room using the split a/c even kept the fridge in there the lowest setting is 17 C but found it went down to 15 C so I have mine set at 19 C and it keeps the room at 17 C and a weight off my mind.

 

[Greg.L]

I have worked at a place with split a/c for a coolroom (for winemaking). Works well because the heat is pumped outside by the compressor. Much cheaper to install than cooling for individual tanks. If you put a fridge in an airtight insulated room it defeats the purpose because the heat is still being contained inside the room - you need to get the heat out of the room. I live in a place with cool nightime (below 10c often even in summer) temps and have thought of a vent fan with a timer to pump cool air inside at night when the temperature drops. My cellar is well insulated but no electricity nearby so I would need a solar battery setup.

 

[wide eyed and legless]

My initial intention Greg was to take the fridge out, because before I got the split a/c in the fridge would push the temperature up, but because the room is now at a lower temperature the fridge on -off cycle is a lot less so I am not getting any noticeable heat from the fridge compressor.
Aside from that I couldn't be bothered moving it out as I would have been moving it back in for the winter as a source of heat.

I have thought of buying a solar set up for my greenhouse hydroponics, I have seen them with a 12 AH battery for $200 inc controller and solar panel on Aliexpress free delivery.

 

[mrsupraboy]

to anyone thinking of getting an air conditioning unit for under 21'c. you would be lucky for it to hit 21'c with out the ac icing up. most Ac's aren't designed for under 21'c. you would be better of getting an old bucket freezer/fridge and changing the thermostat in it..
believe me its my trade. and for the air conditioner to get there if it did . the amount of electricity you would use is for nominal. and getting a bigger air conditioner may get it there faster but still more electricty

 

[Feldon]

Mrsupraboy (and others), can you comment on the claims made by CoolBot (here http://www.storeitcold.com/index.html ) which I posted in the first page of this thread (see the FAQ page in particular).

Seems these guys have done it with much less energy consumption and using an air-con.

 

[mrsupraboy]

haha putting a management system on an ac is pointless. it will just change the external deadband in the thermostat to stop start up on the compressor as much so instead of operating at 1'c it would be more. but obviously regardless of system fridge, air conditioner, freezer. the area you are trying to cool is gonna be what costs you the most electricity and how well its insulated. the difference between an air con, fridge and freezer are the designed temps they are designed to work on e.g. a/c is 20 to 24'c, fridge 20'c to 1'c and freezer 2'c to -22'c.

 

[Ducatiboy stu]

They way I see it as working is that it cuts the compressor just as it ices up. If you put a thermometer in the output, it will measure about 12-13*c normally.

Its the icing up that stops the unit cooling. So if you can stop it ftom icing up it can continue to cool.

Note that it requires a fairly well sealed room that doesnt goet open and closed often.

Its pretty much a 2 probe STC.

 

[mrsupraboy]

the problem with that is, is that the compressor uses 10x power on start up so it would be using more power not less

 

[Ducatiboy stu]

The other thing they say is to buy a bigger unit than required. I suppose they are working on the idea that a bigger unit doesnt have to work as hard.

 

[wide eyed and legless]

I have a split a/c which as I said in an earlier post the temp goes down to 15 Celsius when set at 17 Celsius (the lowest setting) which it can maintain on a 50 degree day I haven't put it in a sleep mode and it runs constantly day and night the compressor kicks in when it needs.
What sort of A/C are you talking about Mr Superboy?

 

[MastersBrewery]

the other thing I've seen is extra/external fans blowing air back on to the cooling fins controlled by stc to stop icing up, this apparently works well. The cost of using any cooling system really has 3 factors, one being the insulation, the next external ambient temp and the third being amount of ballast at set temp. If you have 2000L at say 5c with insulation and moderate active cooling, it really isn't going to move to quickly in either direction.

 

[Greg.L]

I don't understand the claims about icing up at 21c. The compressor is outside the room on a split system. My compressor for my house ices up outside in winter when I use it to heat, the temperature outside might be -2 below but the unit runs for a couple of hours before it ices up, then it de-ices itself by running in reverse for a few minutes. When using split a/c to cool, obviously it is the fan inside that runs cool, mine drips a lot but I have never seen ice form. If it did form ice it would still be cooling down the coolroom because the hot side is the compressor outside, having ice inside a coolroom would still be cooling it down. As far as I know the theory about drawing huge amounts of power at startup is just an urban myth, I have asked several professionals about this and it doesn't seem to be true. A/C units the days run on DC from inverters so they are pretty efficient for power use.
I still can't see the point of putting a fridge in a coolroom, it seems a bit like leaving the fridge door open down to cool down your house, might work for Homer Simpson but not much good for the rest of us.

 

[Ducatiboy stu]

Couple of points Greg.

Most units have a sensor to stop it icing up.

If it ices up it will no longer cool because the head unit cools by drawing air thru the cooling fins. Once they are blocked by ice ( or dust ) it can no longer draw cold air.

The amount of ice in the head unit will cause no coolong effect. It wouldbe like puting a bag of ice from the servo in your coolroom and expecting it to cool it down.

Your outside unit will ice up normally when in heating mode. Thats why they are called revers cycle. You will notice in summer that the outside unit will blow hot air.

21*c more reffers to the temp a unit will maintain and cool for a given room size. The head unit usually blows air out at about 13*c. The smaller the room the lower it can cool & maintain the temp. Keep in mind that the cooler the room the greater the chance the head unit will ice up as it drawers colder air throught the cooling fans.

A reverse cycle air-con is a heat pump. It moves heat from inside to outside by sucking the warm internal air thru the cooling fins in the head unit.

 

[MastersBrewery]

Air conditioners being used for cool room use have been well documented on our American cousin's site, including fixes for icing issues. I'm not going to say do a search, but there is plenty of info out there from other HBers who have successfully implemented such a system, all the way down to fridge temps.

MB

 

[Greg.L]

Your outside unit will ice up normally when in heating mode. Thats why they are called revers cycle. You will notice in summer that the outside unit will blow hot air.

It depends a lot what unit you use. My unit is a fujitsu, it only ices up when the outside temp is very low, below 2C. Other cheaper units will ice up much more quickly. I agree that an iced up unit will not work very well for cooling, but the ice should melt and the unit restart. The humidity will affect how well they work, if you send the drip water outside the coolroom should stay pretty dry, but in the tropics the humidity may cause problems. I don't know how low you can go with a decent split a/c but I think it should be well below 21C. They don't ice up instantly, it takes a while, but of course it will depend on the unit you choose how well they cool. There are some pretty crappy units around, like anything you need to choose the right unit for what you are doing.

 

[Ducatiboy stu]

Air conditioners being used for cool room use have been well documented on our American cousin's site, including fixes for icing issues. I'm not going to say do a search, but there is plenty of info out there from other HBers who have successfully implemented such a system, all the way down to fridge temps.

MB

True, but it will only get a cold as what the head unit pushes out. And not a lot push air out at 4*c.

 

[mrsupraboy]

It all comes down to design. Acs are not designed to run at them temps. Yes u can put a De-ice stat on the evaporator. But Acs are not designed to run at that temp lower than 20'c. At 410kpa there running at 2'c temp. Acs are pressure temp related. Meaning a drop in pressure is a drop in temp. Delivering about a 10'c temp difference over the coil. Once the temps drop so does the pressure. Resulting in icing up. Fridges and freezers run on different gas enabling them to operate at lower temps. Yes u may get one to work after a lot of stuffing around. But not as easy as just putting a new smart controller on it.

 

[redcane]

I finished my cool room using the split a/c even kept the fridge in there the lowest setting is 17 C but found it went down to 15 C so I have mine set at 19 C and it keeps the room at 17 C and a weight off my mind.

Good stuff! I got mine working with a second hand box unit a/c, but the fan failed after a month or so. I now have a Kelvinator KWH15CMC, and it's much quieter with less vibration. It's only got analogue controls, and on it's lowest setting the cool room gets down to 15°c.

Aside from that I couldn't be bothered moving it out as I would have been moving it back in for the winter as a source of heat.

I still can't see the point of putting a fridge in a coolroom, it seems a bit like leaving the fridge door open down to cool down your house, might work for Homer Simpson but not much good for the rest of us.

See the above Greg - in winter when the ambient temp is too low and the cool room gets too cold, a cooling only air conditioner can't heat it back up. The fridge compressor generates some heat, hopefully enough to keep the temperature where the a/c is set. Yes you could just run a heater, but if you were running the fridge outside the cool room anyway you can use the waste heat this way.

Additionally the fridge can more easily vent heat in the cool room in summer so it shouldn't work as hard and less heat should transfer back in. Yes it makes the cool room cooling unit work harder as a trade off.

My future plan is to put a small freezer unit inside the cool room to put my serving kegs in with taps out through the side of the cool room. Basically I'd have a small chamber about one keg deep at ~4°c along one wall, which would also form a small bench when not swapping kegs, and the rest of the cool room would run at fermenting temps. If I was really tricky I'd set it up so it can vent heat outside the cool room in summer, and open vents within the cool room in winter to keep it at fermenting temp.

 

[Greg.L]

Vents are the way to go if you live in a cool area and want to save money. I have looked in the past for 12 or 24v dc vent fans but couldn't find any. (if anyone knows where to get one let me know) .If you have power connected you can put in an ordinary ac vent fan plus an inlet to let cool air in, with a timer so it only comes on a few hrs in the early morning. Fairly cheap and easy to install.

 

[wide eyed and legless]

Have a look on Alibaba Greg, although they deal in quantity they often will send out a sample at your cost.