Cfwc Woes-help And Advice Needed.

[Justin]

Hi guys, well I brewed a lovely 50L batch of German lager with a mate on Saturday that turned into a bit of an epic with the most dramas I've experienced brewing for some time now. It all started when it came time to chill. While the brew was progressing I helped my mate build his new counter flow wort chiller that we planned on using that day. Now I'll explain.

We used 7m of 3/8" copper and a garden hose, soldered the T fittings and set it all up, ended up using 5/8" tee's and some bits of 5/8" tube to provide a bit more flow at the fittings, but regardless it had 3/8" copper as the internal pipe with a normal 1/2" garden hose on the outside.

Water flow around the outside of the chiller apeared to be pretty good, no leaks so all seemed well. On testing the internal flow with his pump we found there was a surprising amount of resistance to flow through the 3/8" pipe though (there were no kinks etc), which I guess is not surprising and certainly won't hurt the chilling capacity (slower flow, cooler wort etc.). However flow was still acceptable but not particularly great for draining 50L.

Now, our tap water was 16C (his is a bit warmer than my water, I have 12C water ) and we wanted to chill to our fermentation temp (basically aiming for 10C in the fermenter for immediate pitching). Running the chiller we could not get it to chill better than about 22-24C, even with a super slow wort flow. We obviously knew we were not going to get below 16C so had our prechiller set up to go and started feeding 6-7C water into the chiller. The best we could see was about 12-14C. Utter crap :angry:

What the hell is the go with these chillers? This was my first experience using one and I am certainly none too impressed. I have to ask some questions. How do you best use them, what sort of performance do you see-compared to your tap temp, how fast do you have the wort and water flowing? Help.

Just as a bit of additional info, my 3/8" immersion (he has a 1/2" immersion as well) chills 30L from boiling to pitching temp in 15-20mins, 25mins to lager temps and I can easily get to within a degree of tap temp pretty quickly. With a prechiller we can get down to 8-9C quite easily with the help of a bit of ice. We would use about 2 bags.

So we ended up with 50L of 22-24C wort and half a yeast cake to pitch each. There was no way that much yeast was going into wort that warm, the fermentation would have been done before it even got half cold. So we had to keep recirculating the wort with the pump from fermenter, through chiller to fermenter again while going through bags and bags of ice. We stopped when we had 50L of 14C wort. And a very long day.

On top of that the council decided to mow and whippersnip the vacant block next door while we were messing around trying to chill, with open fermenters and luke warm wort. Grass and crap drifting everywhere. Fingers crossed it turns out ok.

What are your thoughts guys?

Cheers, justin

 

[Jovial_Monk]

Ummmm you did 'wire' it up right? hot wort circulating down, cold water circulating up?

Jovial Monk

 

[Justin]

Yep, no problems there. Checked and double checked that, but that was a good question to raise JM. Otherwise we would have just had a flow wort chiller eh . Any other thoughts JM. I just can't for the life of me think why we couldn't get it cooler. The only thing we could think of was laminar flow within the centre tubing reducing the efficiency, but yet plenty of other people are using this set up with supposedly good results.

Is there anything else obvious that we may have missed. I wouldn't have though there would be too much involved in running one.

 

[jayse]

Now, our tap water was 16C
snipped>
Running the chiller we could not get it to chill better than about 22-24C, even with a super slow wort flow.

How slow is super slow, sounds more like just teething problems in its use rather than any equipment problems.
Looking at using a pump iam not sure how slow you can actually go. I run a very very slow drizzle to get it close to the tap water temp any faster and you would expect around 5c above tap temp which puts 22c wort coming out and 16c water going in about right. With 16c water you could get it down to 16c but you would have to go very very very slow 50litres would need to take nearly a hour. Mine is 12metres long and takes 30mins to cool down 20litres as cold as your after.
The only thing i can really see there is your super slow wasn't slow enough, Sounds like you may have already collected a lot of wort before you found out how to get in down cool enough, hense you had to send it through again.
Thats all i can think of.

Jayse

 

[Justin]

Yep, all fair comments. We did collect a couple of litres of warmer wort which was going to add substantially to the temp in fermenter (actually we had 2 fermenters). I did expect it to be more efficient though and we were sucking it though with a pump but the flow rate was still very low. We had to pump because his kettle is on the ground.

Guess we might have another go with some boiling water and see what comes out. You must use a heap of ice then jayse if you want to get the temp right down, running the water through ice for a long period. I think this is where the immersion comes into its own, you can use normal tap temp water to drop the temp right down then just add ice to your prechiller to pull it down those final few degrees.

Cheers and thanks guys.

Justin

 

[pint of lager]

Yes I am with Jayse, I think you need to slow the wort flow. After doing some reading, we made our cfc about 8m long as per another brewer's, and this was way too short. With some difficulty, adaptors and brazing, it is now about 15 m long and works a treat. The counterflow cooling water flow rate is also slow, due to low pressure water system.

The wort flow is gravity fed, not pumped and takes about 30 minutes to run 45 litres of wort off. At the start, when there is a decent head of wort, the runoff temp is a little high, but as the wort level drops, the runoff temp is close to the tap water temp.

 

[jgriffin]

I was about to buy the Goliath 6m CFWC - am i reading right that this won't be effective enough?

 

[pint of lager]

Will let someone else comment on the Goliath version, as ours is all homemade, not from a kit.

 

[Doc]

If you want a quick chill then maybe the therminator is for you. They claim 10 gallons in 5 mins.
However for less than US$200 (the cost of the Therminator) you could build a 25 meter CFWC and probably get close to the mark too.

Does anyone know in rough numbers the cooling efficiency increase of convoluted cfc's over cfc's ?

Beers,
Doc

 

[Justin]

It was really just a new toy and supposed to be a bit of an equipment upgrade. However, I thought they were as good or even better from a time point of view as an immersion chiller. Therminator would be nice

I wonder about the convoluted ones too Doc, considering I was thinking about buying one the other week but backed out. I figured I didn't need to spend another $150 to chill wort when I already had a perfectly good chiller. I have no doubts that they are better speed wise, but I think the really nice part about the convoluted ones was there ability to be permanently mounted to your frame and their compact size. I like this side of them immensly.

Cheers and thanks for the input guys.
FWIW I don't think I'll bother building one anymore anyway. My immersion works fine.

Justin

 

[Tony M]

Hey Doc,
My chiller is only 4 metres of 1/2" copper pipe which I crimped every 40mm..
With a flow of about 0.7 litre/min, I can maintain a 4C differential between water temp. and final wort temp. and I only run the garden hose at about 450 litre / Hr.
These flow figures are off the top of my head and would mean that my cooling water would come up 7C which sounds a bit much. I am doing a brew about Wednesday so I shall measure everything accurately and if a couple of others do the same you might get an idea of relative efficencies.

 

[sosman]

Does anyone know in rough numbers the cooling efficiency increase of convoluted cfc's over cfc's ?

Doc although not a direct answer, on brewery.org there is an article about the thermodynamics of CFC's. Turbulent flow from memory is around 10 times more efficient heat transfer as laminar flow.

On that basis (cf personal experience) be careful in slowing the wort flow down too much (and making it longer). Once you slow it down to laminar flow, your heat transfer could drop dramatically.

 

[dicko]

Without commenting on the cooling efficiencies of each and everyones design on CFWC's a simple hint that I might offer is to sanitise and then chill your recieving fermenter in the fridge/coldroom /freezer, which will, in turn, bring your wort temp down another few degrees.

BTW, my chiller drops the wort temp to approx 5 deg c above tap water temp and I run the wort through the 3/8" copper pipe flat out with the March pump and run the tap water flat out through the chiller.

cheers

 

[Tony M]

I promised I would gather some figures on my backyard CFWC. For what they are worth, here they are.
Chilled 22L wort from 88C to 24C at 0.92LPM = 24min.
Cooling water flowed at 10LPM X 24min. = 240Litre
Cooling water temp 21C to 27C = 6C rise
Cooling coil 4100mm. X 12.7 OD copper crimped every 40mm. and with 20mm. polyethylene water jacket.
The above figures would be fairly accurate for the heat in and heat out calcs. are within 2%, but I have no idea how to come up with some sort of efficiency figure. Perhaps someone out there who did a bit of physics later than 1959 can help. If I compare these with the sales blurb that is quoted for the therminator, my effy. is about 1%

 

[Justin]

Ok guys, thanks for the input. I think we have tracked down the problem. My mate did another test run on the chiller yesterday using his left over sparge water from a Belgian Strong Ale (8% ).

It seems that we were simply not running the chiller fast enough, hence creating too much laminar flow and losing efficiency. Because he has his boiler on the ground there is no head to the chiller and it dribbles out really slowly, so we knew we were going to have to use the pump, which is just one of the IDRA pumps often talked about. Basically even with the pump we could no get much of a flow, the pump just doesn't suck hard enough coupled with the resistance from the 3/8" tube.

As I said he had another go yesterday but this time using the 80cm head from his HLT and it chilled to within 4C of the tap water and ran alot quicker-so they need to run fast to work properly. This still isn't going to be good enough for lagers but will do for ales. Perhaps a new pump and some more playing would see better performance, however I still think that this chiller will be decommisioned and probably see it's 3/8" internals being converted in to a 3/8" immersion prechiller.

Thanks to all those who helped and offered advice.

Cheers, Justin