Curious,

/K

Oh, and on re-assembly the pipes very close to the captive nuts are hot of course. There is enough room to work but you can discover the heat when first putting a case back on. Dropping one of the screws inside the case doesn't help, once you do this you don't do it again.

If I understand correctly then provided there is little temperature difference by the time water reaches the puck it's a really useful device. If, however the temperature varies enormously (or inconsistently) then it may be misleading and unreliable. What do you think?

I was stunned by the taste of coffees I know well, to the point of leaving the evening early for some shut eye and driving to Guildford for Saturday morning opening time. I'm entirely with Dave when he says tests are futile because once tasted you have nothing to prove to yourself, you simply vow not to ruin any more of your beans.

Why? Well, it's as if a blocker, some kind of veil or heavy dilution is taken out of the way allowing you to taste the bean for the first time. It's not the freshness that struck me most but the pure definition of flavour. My first roasts were already in the cupboard within an hour of arriving home, sealed and being checked from time to time.

Once you understand the science (Dave has posted it in articles and in forum posts) you would expect to see big differences to the Gene data above such as:
- 225g is an exceptionally low batch size for a Gene, it does not need nursing like a Hottop in cool and cold weather
- We quickly established that increasing the batch size of the Gene to 250g or more will shorten the roast time ("heat trap principle")
- getting sufficient heat ("thermal input") early on and turning down after 1st crack avoids scorching with a Gene and improves the roast flavours
- the controllability allows you get to know how a type of bean needs to be roasted
- I doubt any owner gets a gap of more than 3 minutes between 1st and 2nd crack and an overall roast time exceeding 16minutes & xx seconds except for the occasional hard bean (assuming appropriate voltage/element match)

I have to undertake this at some point. As we know, we established when looking at my MKII that the changes are evolutionary and mine does not have this top plate ventilation.

BTW, I thought this would allow Alex to "keep her cool" (given the name origin) :-)

South America did not fascinate me before getting into coffee but I can feel a road-trip coming up in the next handful of years :-)

http://www.home-barista.com/forums/boiler-fill-level-impacts-shot-temperature-stability-in-pid-d-espresso-machines-t4270.html

Question though, what happens with commercial machines in use en masse in the high street the world over? Do they work differently or do they need a cooling flush because many operators don't do this when preparing your mate's drink (I'm assuming most of us order tea if anything when we're out and about :-) )

There are of course:
Those who have joined a forum but haven’t posted….yet
Those who have joined a forum and have posted
Those who have joined a forum and posted and wished they hadn't
Those who have joined a forum and will never post

Why?
Web-lore says so.

The general concensus has traditionally seemed to be that the Hottop gives mellow, matured flavours against the bright under-developed results of the hot-air roaster Gene Cafe and that one naturally upgrades if moving from a Gene Cafe to a Hottop. Our goal was to put this to the test.

Our conclusions migh be summarised as disputing the web-lore.

- The Gene Cafe appears to produce results which are at least the equal of the Hottop
- expensive CoE bean purchases might be justified with a Gene Cafe and perhaps less so if using a Hottop as it mutes so much of the subtle and delicate flavours

- commercial roasters know that a certain roasting time range is required to avoid spoiling the beans even though this information is not commonly found, if one roasts in the Hottop according to convention then it is in excess of this range and the muting of the roast is increased, otherwise one has to lower the batch sizes of the Hottop considerably in many seasons (depending on your climate), the Gene Cafe seems to be impervious to this limitation
- The Hottop needs time to cool down between roasts however the Gene Cafe roasts back to back without problem as required

- The whole Hottop machine by design becomes aged and dirty through use and has expensive running costs in proprietary filters
- The cleanliness of the Gene Cafe and ease of clean up makes a mockery of the routines required to keep a Hottop in good condition, Only the roasting chamber in the Gene Cafe ages through coffee oils and contact with the roast and is replaceable, there are no filters to worry about unless one opts for the larger chaff container which is not needed for domestic home roasting

- the Hottop is wonderfully silent (if you get a good one and they do vary) making 1st and 2nd crack easily the most audible of the home roasters, the Gene Cafe is harder work in this respect
- the Gene Cafe counters with a vastly superior visibility of the beans tumbling and roasting enabling one to see the roast develop but it should be noted that to maintain the roast level you chose to stop it at you need to consider how you will allow your beans to cool as this can change the roast a bit

- The Hottop profiles are merely additions of time and even if the incredibly expensive digitally controlled model overcomes this it will need to be able to drop and raise the temp quickly to take advantage of what might otherwise be gimmicks whereas true profiling and fast temperature adjustment is available with the Gene Cafe

- One can overcome the common criticism that the slow Gene Cafe cooling affects the roast by ejecting early and sieving the beans for fast temperature reduction

Or, to put it another way:
- The Hottop was made to be a scaled down design of what a coffee roaster is expected to be where function follows form
- the Gene Cafe is an intelligently designed solution to a set of scientifically approached problems where form follows function

A number of us were sufficiently impressed to buy a Gene Cafe (at least two of us selling our Hottops in the process)

I know there's not much personal experience available in this type of roaster, or even from the segment which used to be held by commercial sample roasters. But anything that has more 'seriousness' to what is presently available with the Gene/Hottop duo, at least for me, is quite valuable information.