you will have to forgive my ignorance here- my knowledge of the more professional technical aspects is limited:

my idea was to have the machine ship with both manual and plumbed option installed. certainly a lot of home users don't want to have a plumbed machine. Will a vacuum breaker set up work on such a set up?

Also how should the plumbing work? Auto fill? With a some kind of electronic water level indicator to trigger re-fill?

If you utilise a manual fill system- how do you stop people damaging their elements?

When you have a plumbed system does it always draw in a little water whenever some water is taken out?

what's the best (and simplest?) way to set this all up?

The Regina was a machine I saw on Ebay.fr once. Never saw another one.

I agree that levers are attractive because of simplicity. You should, at least, have easy access to pressurestat adjusment however, as in not needing to disassemble anything. I recently realized I needed this on my PV Export, so I just drilled a hole in the bottom of the base. Now I can adjust pressure (and therefore temp.) in 1 sec. This makes it easy to dial in different beans etc.

AND, I think a simple means of monitoring group temperature, if possible, would be a vast improvement over my current method (ouch! its hot!).

Just a sight glass, minimo/massimo stickers and an overtemp switch would do nicely. No need for autofill gadgetry.

do you mean manual fill only (like a PV)? Or plumbed manual? i.e. you operate a valve and the machine fills to the 'massimo' line, and you close the valve?

and where does the overtemp switch go? Do you have a probe on that one- or does it come right off the element?

I notice the PV has a low water level cut off? Good idea? Seems so to me.

Jack: when you say adjust the temp in a second through the pressurestat setting- how practical is this? Because I was thinking if you had a temp/pressure dial at the front of the machine so you could dial between say 0.8 and 1.4 Bar (tightly controlled within that range) would that give the user the temperature control so many crave? Obviously you get varying pre-infusion pressures but it could give that little bit of control over temp... If you coupled such a set up to a temp gauge on the group? overly complex? Un-neccesary? Problematic?

I notice OE and yourself both suggest using the pressurestat to 'dial in' different beans?

Can anyone explain to me the relationship between pressure and temperature? Specifically in relation a lever machine?? What would the temps be between 0.8 and 1.3 Bar?

How important would it be to match a boiler to a group?

http://www.engineeringtoolbox.com/boili ... d_926.html

There is table and figure. At 1 bar water boils at 213F. That's toooo hot for espresso, hence all that brass!

My point is that it would simple for an average barista to develop a relationship between the temperature of the boiler, the group temp., and how he likes his espresso. E.g. if you keep your boiler at 1 bar, and the group is X, the espresso will be too cool. When the group gets to Y, the espresso is perfect, when the group gets to Z its time to take out the wet towel. Not rocket science, but better than using your finger on the group.

peacecup wrote:http://www.engineeringtoolbox.com/boili ... d_926.html

There is table and figure. At 1 bar water boils at 213F.

Wrong numbers. Those tables are using absolute pressure (P.S.I.A.) wherein 1.0 bar is one atmosphere of pressure in an unpressurized boiler at sea level, or 0.0 bar on the pressure gauge. A reading of 1.0 bar on the pressure gauge is more on the order of ca 250 F.

Here is another table that gives both P.S.I.A and P.S.I.G. numbers, albeit without the fine granularity that will be helpful.

so 250 F at 1.0Bar on the pressure gauge- would mean an internal boiler water temperature of 121 C??

So my Ponte Vecchio which I have set at 1.1 Bar has an internal temperature in excess of 121 C?

and a group head temp around 93-7 C?

jmc wrote: Site glass - use the simplest way to manufacture it. I think that having a large opening in the boiler is asking for problems in the future. Separated tube.

I agree that the level indicator - if it's a sight glass - should be a tube separate from the boiler. I think it should be within the frame of the machine, however, and not an exposed piece of glass tubing hanging on the outside where some fool is going to bang into it with cups, pitchers, portafilters and the like.

Separate from the boiler, but within the enclosure.


As for boiler filling - plumbed manual seems like a great idea. Three way power switch maybe? Heat - Off - Fill?
Maybe two level sensors, one for high, one for low - low cuts off heater power, high turns off the semi-automatic fill? Pushbutton starts the fill cycle? (Starting to sound complicated.)

A really nice feature might be providing some relay contacts (or an auxiliary receptacle) for an external reservoir pump. Switch to fill mode and the FloJet kicks in automatically.

I think I'm opposed to the idea of having some automatically triggered filler - what if it automatically kicks in mid-shot? Any interlock method to prevent that just seems far too complicated for a "simple" system.

sorrentinacoffee wrote:so 250 F at 1.0Bar on the pressure gauge- would mean an internal boiler water temperature of 121 C??

So my Ponte Vecchio which I have set at 1.1 Bar has an internal temperature in excess of 121 C?

and a group head temp around 93-7 C?

Yes.

Also, with a temperature switch, i mean a resettable thermofuse emergency type thingy.
I think that either line pressure filling with a valve or just manual with a boiler cap gives the least amount of fuss. No sensors or brainbox.

Wrong numbers.

Yes, I should have noticed that! 213 F is the boiling point of unpressurized water at sealevel!

Well, 250F is even a little more tooo hot for espresso.

The simple thermal cutoff on my PV Export saved my element once when I turned the machine on after forgetting to fill it. Now I try to never plug it in until I am sure its full.

Some simple low water sensor could be nice, but not if its likely to fail. Even one episode of a machine not working when one wants an espresso can be annoying.