dual boiler temp surfing

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dual boiler temp surfing

Postby Justin Teisl on Fri Dec 08, 2006 10:20 am

I've been thinking a lot lately about how to best utilize my linea 4 group. The theory behind temperature surfing tells us that a machine making many shots will experience a more narrow range of water temperatures: how does this apply to a two boiler machine, which is basically two machines in the same frame?

Another thing I've been thinking is that it is not neccessary to keep all four heads operating simultaneously, especially during slower periods, mainly because I keep spent pucks in the pf for heat/seasoning and don't want to worry about that spent coffee sitting in the pf for too long. What I've been doing is keeping 2 heads going for maybe 2 hours then using the other 2 for a while, rotating throughout the shift. This actually has worked well during busier times too.

The conclusion I'm close to reaching is this: use the 2 heads from boiler 1 exclusively for some time, then switch to the 2 heads from boiler 2 for some time. What do you guys think?
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Postby phaelon56 on Fri Dec 08, 2006 11:34 am

I have a tendency to try alternating betweeen the two and when I'm pulling two shots simultaneously (we use the AV auto-volumetric feature) I have them runnign on the twodifferent boilers. This way I minimize the amount of fresh cold water etering the boiler at any given time.

As for temp surfing - we don't have a Scace but I flsh a couple to three ounces of water off the head I'm going to use while the Swift is grinding and tamping (not my shop - this is how the owenrs do it - the AV and the Swift). But if I'm pulling two shots in very short succession I don't do the heating flush. I doubt that the water sitting outside the head in the tube to the flowmeter cools off much in 30 seconds inside the mahcine in a warm shop.
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Postby phaelon56 on Fri Dec 08, 2006 11:36 am

I have a tendency to try alternating betweeen the two and when I'm pulling two shots simultaneously (we use the AV auto-volumetric feature) I have them runnign on the twodifferent boilers. This way I minimize the amount of fresh cold water etering the boiler at any given time.

As for temp surfing - we don't have a Scace but I flsh a couple to three ounces of water off the head I'm going to use while the Swift is grinding and tamping (not my shop - this is how the owenrs do it - the AV and the Swift). But if I'm pulling two shots in very short succession I don't do the heating flush. I doubt that the water sitting outside the head in the tube to the flowmeter cools off much in 30 seconds inside the machine in a warm shop.
Owen O'Neill
Syracuse NY

Phaelon Coffee
and
New York Central Coffee Roasters
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Re: dual boiler temp surfing

Postby gscace on Sat Dec 09, 2006 4:23 am

JustinPaints wrote:I've been thinking a lot lately about how to best utilize my linea 4 group. The theory behind temperature surfing tells us that a machine making many shots will experience a more narrow range of water temperatures: how does this apply to a two boiler machine, which is basically two machines in the same frame?


Temp surfing a Linea is a group-specific practice. The group solenoid (EE) and both group solenoid and flowmeter (AV)are unheated by the hot water during idle periods and must be brought up to temperature after several minutes of inactivity. Linea groups run very cold if left inactive. I had one of the buttons on each group in my AV two group (identical to half of your 4-group) programmed to perform this flush, and I set it to flush for somewhere around 6 seconds. Caviats on group flushing: You need to run quite a bit of water through the group to heat up the flowmeter, so the flush has to be long enough. I'd suggest getting yourself a Scace so you can learn how your machine performs. The stock AV doesn't have a gicleur, so 6 secs represents a large amount of water. You gotta flush for a longer time if you've installed gicleurs. You can't overheat the group by over-flushing, but you can run into recovery time issues. Water pumped into the boiler by the pump during the flush is cold and cools the temperature off inside the boiler. The heating element is big enough to cope with this as long as the flush is reasonable in length. PID-controlled machines with conservatively tuned controllers are most affected. 3-group machines are the most insensitive to this because they have bigger brew boilers than the 2 or 4 group machines. Again, a Scace will show you what's going on.

Group heating has to be done for all groups in the machine, since they each use their own flowmeters and solenoids. If you use two-groups simultaneously you're gonna have to keep them both hot.

It sounds like a pain in the yass, but it's really not. Takes less intuition and practice than group flushing a small heat exchanger machine. The Linea responds really well to flushing and becomes quite temperature stable (same temperature profile each time) once heated.

-Greg

Now that I'm thinking about how good that is I'm a gonna go down to my liddle espresso lab and make my Linea run. As my little daughter is wont to say - " Hi grinder! Hi machine!! Hi coffee!!!" She also says "Cat barf!! Daddy clean it up!!!! Use paper towels."
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Re: dual boiler temp surfing

Postby Justin Teisl on Sun Dec 10, 2006 3:15 pm

gscace wrote:Temp surfing a Linea is a group-specific practice. The group solenoid (EE) and both group solenoid and flowmeter (AV)are unheated by the hot water during idle periods and must be brought up to temperature after several minutes of inactivity. Linea groups run very cold if left inactive.


Sweet, that makes a lot of sense. This seems to confirm my thougts about focusing on just 2 groups at a time, which actually has allowed me to keep all groups even cleaner throughout the day.

Still wondering if there would be any difference between using 2 groups from the same boiler versus using 1 from each. My intuition/reasoning still says use 1 boiler at a time. I'm without a Scace here, so I can't prove this, but I'll keep running it through my head.

Flush on!
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Re: dual boiler temp surfing

Postby gscace on Sun Dec 10, 2006 5:06 pm

JustinPaints wrote:
gscace wrote:Temp surfing a Linea is a group-specific practice. The group solenoid (EE) and both group solenoid and flowmeter (AV)are unheated by the hot water during idle periods and must be brought up to temperature after several minutes of inactivity. Linea groups run very cold if left inactive.


Sweet, that makes a lot of sense. This seems to confirm my thougts about focusing on just 2 groups at a time, which actually has allowed me to keep all groups even cleaner throughout the day.

Still wondering if there would be any difference between using 2 groups from the same boiler versus using 1 from each. My intuition/reasoning still says use 1 boiler at a time. I'm without a Scace here, so I can't prove this, but I'll keep running it through my head.

Flush on!


Yowdee:

It's prolly easier to heat up one group from each boiler than two groups from the same boiler. In the first case each boiler supplies enough wwater to heat up one group each. In the second case, one boiler has to supply water to heat two groups. I suspect that this will cool the boiler water down quite a bit, requiring significant temperature recovery.

-\greg
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