Preheating the Flair Espresso Maker, wet or dry?

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vit

#1: Post by vit » May 18, 2018, 2:30 pm

After some further experiments, my steaming preheat method recently looks like this

Image

Procedure for medium roast (Illy, Lavazza and SO from local roaster) is as follows

- pour about 1 dl of water into czesve, put on the cylinder and the cup; induction set to 9 (no powerboost used)
- while it warms up, preheat the PF separately by pouring some hot tap water to about 40°C
- 1:30 water boils
- 2:00 reduce power from 9 to 7
- 2:45 remove the preheated cup and put on the scale on the Flair, then pour out the water from the PF, wipe, dose the coffee, tamp with 8-10 kg, mount onto stand, put the shower screen
- 3:30 switch off the stove, move the cylinder to the PF with hand (no tongs required)
- 3:40 pour the water from the csezve into cylinder, wait 20-30 s checking the water temperature in the cylinder with thermometer until it drops to around 94°C, then mount the piston and preinfuse with force about 5 kg, about 10 s
- extraction with force around 16 kg (around 9 bar according to my measurements), decreasing the force towards the end to keep constant flow, 25-40 s

For darker espresso blend with significant percentage of robusta, I don't preheat the PF, but dose the coffee at the beginning, then after preheating the cup until around 2:45, I immediately mount the cylinder (which is less preheated than for medium roast) onto PF, pour the water from csezve, wait until temperature drops to 91-92°C, no preinfusion, extraction 20-30 s with constant force around 16 kg (or slightly less towards the end)

Of course, no need for extreme precision regarding the timing, I just wrote it down as some kind of reference, and it should be adjusted depending on the stove power etc ...

Moderator note: A discussion of dry versus wet preheating of the cylinder began in the Flair Espresso Maker Review thread and has been split off so it can more easily be found. -- drgary

MikeTheBlueCow

#2: Post by MikeTheBlueCow » May 22, 2018, 5:53 pm

So I just got a Flair and I've been playing around with different ways of preheating. So far I like the dry heat method, which I achieve by putting the cylinder directly in a pan on the stove. With the boiling or steaming methods it never stayed hot enough for me, but with this dry heat method I actually have to be careful to make sure that it's not too hot. I just wanted to check in to see if there was a reason not to do it this way, since I can't think of any as it isn't getting any hotter than 250 F generally. I'm thinking that isn't too hot to worry about hastened degradation of the non-metal materials, but would appreciate it if someone could confirm our deny that. I'm mostly questioning this because nobody else seems to do it and usually people seem to use boiling or steaming.

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drgary
Team HB

#3: Post by drgary » May 22, 2018, 6:16 pm

Good question. Perhaps you could ask the Flair folks about the heat tolerance of their materials and report back to us.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

MikeTheBlueCow

#4: Post by MikeTheBlueCow » replying to drgary » May 22, 2018, 8:48 pm

Just had a quick communication with them and it looks like the o-rings are good for at least 350° F. It's definitely not necessary to get the heat past about 250° in my basic testing, since I have found that sufficient to get a good temperature and low enough that it won't flash boil too violently. This has given me good starting brew temperatures, though I don't have the ability to tell what the temperature stability is once I put the piston in (so I'm just assuming the same rate of decline as stated in the review). My thermometer and methods are basic, so "your mileage may vary". The heat does get pulled away some to the filter and shower screen if those aren't preheated. You do also have to be careful to not get the cylinder too hot because the flash boil could be violent and cause burns. The silicone sleeve is also very hot so it is good to use tongs or a heat resistant glove, or even a towel has worked for me.

I'm hoping to try this out with a preheated steel piston as well, once I get one of those.

vit

#5: Post by vit » May 23, 2018, 2:10 am

Problem with "wet" preheating methods is water evaporation from the surface of the cylinder between end of preheating and pouring the water in, which cools the cylinder rapidly. Steam method seems to be less problematic than boiling method due to less water remaining on the cylinder and less time needed for operation, because you can do it by hand. In combination with using straight from the boil water, starting temperature should be around typical brewing temperatures at lower altitudes (mine 320 m above sea level) - I'm getting up to 96°C starting water temperature with steam method if needed (but it isn't). However, at higher altitudes this becomes bigger problem

On the other side, I'm not sure how to get sufficiently precise cylinder temperature with "dry" preheat needed to achieve repeatability. Maybe by setting it on the stove/pan and leave precise amount of time ? Also, there will be significant temperature gradient along the cylinder (bottom much more hot that the top). But I didn't try

MikeTheBlueCow

#6: Post by MikeTheBlueCow » May 23, 2018, 6:41 am

My problem with the steam method not getting up to temp was possibly due to using a steamer basket, so the outside was wet as well. Highest temperature I got, after adding boiling water, was 188° F. I see that you use a cezve so that it only steams the inside of the cylinder. I have a cezve but the cylinder is unstable on the top so it isn't a good solution for me.

I did think of the gradient issue, and when I take the temperature, the 250 F is for the bottom, and at the top the heat is just above boiling temp (around 220+). I'm figuring that when I place the cylinder on the portafilter, some of the heat gets sapped away since I don't preheat that to the same temperature. When I add the just-off boil water, it re-boils, and I measure the temperature with a thermometer and watch it go down to whichever temperature I'm targeting. My thinking is that once the water is added to the brew cylinder and boils, convection is taking place, and all of the water should be at a similar temperature. The water is bringing the temperature of the cylinder down, and stops boiling, reaching brew temperatures within a few seconds. I'm hoping that the gradient is either minimal or not an issue. Overall, the temperatures are better for me than when I've tried steam heating or boiling, since for me both of those are more elaborate setups and don't seem to get the temp high enough.

I am thinking of adding insulation to the cylinder after I place it on the filter. In the review they showed that with the plastic piston we are losing 1 degree F every 5 seconds and these brews take 25-45 seconds resulting in 5-9° of loss, which seems like a lot to me. That is halved with a heated steel piston though. I'm curious how much an insulating jacket could improve temperature stability.

vit

#7: Post by vit » May 23, 2018, 8:33 am

Yes, finding suitable vessel for steam preheat is essential I think. I was lucky to have this small czesve (bought it a few years ago and used only a few times since). Metal part of the cylinder protrudes into it, while the silicone sleeve sits on the neck and seals quite well, so it is stable and almost all steam goes through cylinder to the top and then heats the cup as well, while outside of the cylinder stays dry and I can hold it by hand for a few seconds (although it's quite hot, my estimate at something around 50°C). Plugging the top of the cylinder (or not) also makes some difference I suppose, as well as stove power (and produced amount of steam)

I was thinking about what you wrote in the last post in the meantime and sure, even if "dry preheated" cylinder is above boiling temperature, it will quickly cool down by water boiling inside and then continue decreasing at slower speed, so temperature surfing will consist of waiting certain time (although if too long, it could affect the taste - similar like darker italian blends didn't like to be about a minute in preheated portafilter which was my previous procedure - it killed much of remaining aroma).

As about temperature stability during the brew, when the piston is mounted, whole thing doesn't cool that fast because there is no water evaporating from the surface. I did some measurements, got some different results depending how I did it, but it looks like it is within something like 1-1.5°C (depending how long it lasts). It's however worse if cylinder isn't preheated to the brew temperature, because it cools the water in it, so original preheating method was unusable to me even with dark roast, while preheating it by pouring hot water twice before brew was barely usable with high temperature drop during the brew and limited to dark roast, but not practical because several seconds lost before the brew changed the temperatures quite a lot. Opinions about this are different here because several of us tried measuring it different ways and got somehow different results

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sweaner
Supporter ♡

#8: Post by sweaner » May 23, 2018, 9:47 am

Has anyone tried a heat gun to preheat?
Scott
LMWDP #248

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SunSurfH2o

#9: Post by SunSurfH2o » replying to sweaner » May 23, 2018, 10:32 am

My experience with using a heat gun is the curvature of cylinder, perhaps reflectance, creates erratic readings; silicone sleeve provided slightly more consistent readings.

jpender

#10: Post by jpender » May 23, 2018, 1:33 pm

vit wrote:Problem with "wet" preheating methods is water evaporation from the surface of the cylinder between end of preheating and pouring the water in, which cools the cylinder rapidly.
Can you quickly towel it off?