Tuning the freezer loop, or "I was told there would be no math"

So I got home yesterday and went to look at how well the temperature is regulating in the freezer with the new Johnson Controls A419 temperature controller attached. The setpoint is 64 F, the temperature reading at 6:00 PM yesterday was 58 F. Hmm.

The controller's default configuration is "cut in," meaning that when the temperature exceeds the setpoint the controller cuts in the power and the freezer starts to cool. The controller has a "differential" setting (by default, 5 F) which determines the point below the setpoint at which the power is cut out. It's a coarse method for adjusting temperature.

Here's what I see happening:

• the freezer warms up to 65 F and the power cuts in, turning the compressor on and starting the chill process.
• the freezer stays on until the controller reads 59 F (64 - 5) and cuts off the power
  
• the temperature reading continues to go down briefly as the coils absorb a little more heat, but then it starts to gradually rise as the inefficiency of the insulation allows convective heat exchange with the outside air and the heat of the compressor

I didn't measure how long this process takes. (The cooling is pretty quick. I don't know how long it is between cut out and cut in.)

The questions I have are - a) is a regular 7 degree swing in temperature OK during fermentation, as long as the range is within the appropriate band for the yeast? b) is this constant cycling bad for the compressor? For (b) the answer is likely dependent on the cycle time. For (a) I need to consult some of the experts at HBT.

Edit 4/30/2009 21:00 CDT: Check out this thread at HBT for some detailed commentary on this issue.

Like Christmas morning

So I got home yesterday afternoon and rushed to the basement to unpack all my equipment and inventory it. ("Yippee! A Zeppelin!") The first thing I realized after opening up the boxes was that I need some containers to store that stuff in when it's not being used. There are lots of little pieces that could create a tragedy if they go missing during a batch.

Anyway, I have a nice shiny new keg and regulator, two glass carboys for my primary and secondary fermentation, lots of miscellaneous items like a racking pump ("this sort of thing ain't my bag, baby"), a hydrometer, and two typewritten pages on how to hook it all up. Two sided. Two column. Small print.

I hooked up the temperature controller to the freezer to check its performance. I set it to 64F to see how it would do for creating a fermentation environment. (I'm also using to check the calibration on my cheap thermometer.) I'll check it after work today to see what temperature we have. I'm a little concerned about a deep freeze regulating at over 60 degrees - where does the heat come from once the coils have cooled themselves to 0?

I placed an order for the grain I need to run the first two batches. It's scheduled for delivery Friday, so there's a chance I'll actually run a batch this weekend.

Equipment delivered

I got three boxes of stuff Monday. I didn't have time to open them and inventory because of some research I was doing (soccer related of course). Maybe this afternoon.

That wasn't what I expected

I re-ran the wort chiller test today, and this time I used the pre-cooler in a water/ice bath to try to create a larger delta T between the coolant and the wort.

I attempted to duplicate the test conditions from Friday as best I could - I used the same volume of water in the boil kettle, I measured every two minutes, etc. There were some unavoidable differences though - one being that I had a dedicated probe for the wort temperature, I started measuring very near boiling (no leak to fix this time) and I was more rigorous on the timing of the measurements.

The result? No effective change in the time spent in the 120F-80F "danger zone." Here's the graphic proof. (You'll have to click through to be able to read it, sorry.)

I think the reason is simple. I measured the temperature coming out of the pre-cooler, and it was right at 63F. That was only a 3 degree drop from the supply temperature, which indicates that the pre-cooler wasn't doing much for me. I think I will have to get more tubing to build a better heat exchanger for precooling, but I'm not going to do it right now, because I expect my brewhouse supplies to arrive tomorrow and I need to get ready for the first batch. The cooling performance I'm seeing is (I think) good enough to get started.

Chiller test

I tested the wort chiller (without the pre-cooler) by boiling about 7 1/2 gallons in my brew kettle, then cranking up the chiller. I measured the drain temperature of the cooling water and the "wort" temperature every two minutes until I got tired of it (and the "wort" temperature flattened out), which was about 20 minutes. The chart starts at 198 F because when I engaged the cooling water my inlet sprung a leak and I had to fix it. It took about 2 minutes.

The early cooling performance was good, but as the wort got closer to the cooling water temperature cooling slowed dramatically. I could probably dust off my thermo book from Memphis State and figure out why but I'm just not that interested. I think I should probably plan on using the pre-cooler all the time to create a bigger delta T so the wort doesn't spend so much time between 120 and 80.

Also, the garden hose I used to hook up the hot side of the chiller warped really badly while I was in "sterilize" mode before chilling started. I think I will swap it out for something with a bigger temperature tolerance.



My Mech E friend Mark looked at this profile and confirmed that I should be using the pre-cooler all along (while thinking "that's what you get for letting a software guy do cooling" I'm sure). I'm going to run another test this weekend with the pre-cooler to see what the effect is.

Pre-cooler

I used the remaining copper tubing to make a small pre-cooler for the cooling water. I got the idea from this post, whose author faces climate conditions similar to mine. My plan is to put the pre-cooler in a small ice bath, run the cooling water into it first, then from there run it to the wort chiller.

Here's a shot of the pre-cooler and one of the complete system:

Decisions, decisions

What should I make first? I need to decide so I can start laying in the materials. I won't have enough equipment to lager anything just yet so I'm looking at ales. Using Beer Smith, I have transcribed some good looking recipes from posters at HBT.

From Biermuncher's recipes, I'm thinking about

• Aberdeen Brown Ale - a Newcastle clone
  
• Ode to Arthur Irish Stout - a Guinness clone, but I don't have a stout tap or nitrogen system to serve it with yet
  
• SWMBO Slayer - a Belgian blonde ale - I think Amy might like this
  

I also found a Sweetwater 420 clone recipe called Coldwater 420 courtesy of another HBT poster.

Seeing as how it was Newcastle that got me into this whole thing, I'm thinking brown ale. I'll tweak the recipe for local conditions and call it Geordie Ale.

Chilling

I separated my 1/2" OD copper tubing into two segments, and took the 35' one to convert to an immersion wort chiller. I generally followed the instructions from this All About Beer page.

Word to the wise: bending the 90 degree angles is tough without the spring tubing bender - I put a decent size crimp in the inlet run but was able to recover it for the most part. (I'm going to play it off as an intentional attempt to introduce turbulence in the water flow so the heat can transfer more thoroughly.)

I used a paint can to give me a guide for the coil diameter. It's a little too small but I didn't wrap right up against it so the effective diameter is a little larger than the can. The coil has about two inches of clearance from the side of the boil kettle, which is supposed to be right.

It's pretty ugly but I tested it and it doesn't leak from the hose connections.

The completed chiller and the "turbulence crimp":

A tun of work

I put my mash/lauter tun together today. I followed the basic instructions from FlyGuy's tutorial thread on Homebrew Talk with a couple of alterations:

• I started with a 20" supply hose and ended up cutting it down somewhat. It's still longer than the diameter of the cooler, so it bends around a little. I'm going to wrap some some copper wire around it to curve the line a little and add some stiffness.
• My cooler is only about 7 1/2 gallons - it is a Gatorade-branded Rubbermaid I got from a friend of mine a couple of years ago. We've been using it for icing down drinks. I'm starting with 5 gallon batches so that should be OK. I have a bigger rectangular cooler I will switch to if I decide to move up to bigger batches.
  
• If you read down the HBT thread a while you'll see that the stainless steel hose clamps corroded in FlyGuy's installation after a few batches, probably because the screws weren't actually stainless. I substituted nylon cable ties.

I also have the makings of a wort chiller. I bought 50' of 1/2" OD copper tubing from Lowe's, and I plan on making two units - one from about 35' for the actual wort chiller, and one from the rest of the tubing to use as a pre-cooler when the summer comes and the supply water temperature isn't cold enough to chill to 70 F.

What I'm shooting for

I'm starting up with the intention of:

• All-grain brewing
• 5 gallon batches
• Kegging, not bottling

I'm starting with all-grain even though it's not what most people recommend for beginners. I'm not exactly sure why people say that, though - I have watched several tutorials on YouTube and the process, while tedious looking at times, seems simple enough to follow. I'll post some links to the tutorials I found most educational.

Why kegs? It's always been a desire of mine to have draft beer in the house, and after looking into the kegging process it seems like it's an ideal way to realize that desire. I have a chest freezer that I want to convert into a "kegerator" eventually. Right now it's just going to be a temperature-controlled keg cooler.

Introducing Fork and Hay Brewing

This is the place where I will keep up with what I am doing with respect to my home brewing experiment.

I chose the name "Fork and Hay" for two reasons - it sounds like it might have been the name of a tavern back in the day, and because it's a phonic pun. (You have to stretch to get the pun but I think it's funny and that's all that matters.)

I placed my first equipment orders last night, and I'm in the middle of the cleaning process for the brewhouse.