Upgraditis: 2-group Grimac Commercial

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

We went to the same school, JavaB.... but much of the teachings come and go as they please in my memory.

I got side-tracked by thoughts that the sight glass being narrower than the surface area of the boiler, could support a higher level of water than the boiler. But that may be cancelled by the boiler pressure on top of the glass tube.

And the mental picture that conjured was further complicated by the affect steam pressure may have on the greater water surface.

Now I know about using a garden hose to find levels for landscaping.... but a garden hose is of uniform volume throughout.

Think its time to put the mental gymnastics behind me and get some sleep....

[JavaB]

Re: Upgraditis: 2-group Grimac Commercial

We went to the same school, JavaB.... but much of the teachings come and go as they please in my memory.

Yep, but in my case.... Latin, English (except what I need to converse) - gone totally.... French (spent some time in France so that doesnt count)..... But Physics, Chem and Maths.... Loved em then and still do..... and have no problem remembering them (after all they are useful - unlike those other subjects )

OK pressure on the water is uniform... so no effect.... But (to be a purist) as the water in the sight glass is in a smallish tube it will be affected a little by capillary action - and will be a fraction of a mm higher than in the boiler (but for our exercise I think we can ignore that ).

Have a good nights sleep and may you wake to a warm boiler (without too much air ;D)

[segrave]

Re: Upgraditis: 2-group Grimac Commercial

i think that is the best good night saying by far ;D

[MachoSilvia]

Re: Upgraditis: 2-group Grimac Commercial

About the cooling flush, you say you need no cooling flush at 0.8 bar. if you were to pull consecutive shots, would they come out cold, or is the recovery still quite fast? im considering taking the pressurestat on my futurmat down from 1.0 bar, to make steaming a little easier, and make the cooling flush shorter.

Cheers, Mark

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

MachoSilvia, recovery isnt a problem: with steaming or brewing.

Steam pressure is more than adequate at both ends of the deadband: 0.6/7 - 0.8.

I havent accurately measured how much water Ive drawn continuously through a HX, but Im sure it would have been enough to make several shots, and the temperature stayed steady throughout.

-And theres always that second group standing by to utilise too.

--Robusto

[Sparky]

Re: Upgraditis: 2-group Grimac Commercial


Ahhh yes, that second group... For me its like having two Giottos side by side.

One of my groups seems to run a bit hotter though. But variety is the spice of life...

[MachoSilvia]

Re: Upgraditis: 2-group Grimac Commercial

Im gonna have to try a 0.8 bar setting, see how that works for balancing the hx... is there a technical term for balancing the temp? a balanced thermosyphon, i heard that term used somewhere...

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

Ahhh yes, that second group... For me its like having two Giottos side by side.

One of my groups seems to run a bit hotter though. But variety is the spice of life...

I think there is a 1º differential between mine too -- possibly because one is closer to the element.

Not quite 2 Giottos in one --- With your monstrous boiler youll never have to worry about falling steam power, recoveries and all the rest.


-Robusto

[JavaB]

Re: Upgraditis: 2-group Grimac Commercial

Not quite 2 Giottos in one --- With your monstrous boiler youll never have to worry about falling steam power, recoveries and all the rest.

-Robusto

Yep, wait until your SO invites 20+ people over for coffee (or a reasonably frequent basis)...

Thats when you appreciate that you havent got two Giottos in one!

By the way Robusto, how was the boiler this morning? Still have to bleed off the air?

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

As i drove home from work last night I got SO to time the cycles and relay them back by mobile phone. Yep, still air in there then. So SO bled the steam wand and all was OK.

Since were all at work today, and wont be requiring coffee until tonight, I switched it off last night and will attend to the problem when I get home.

Ill have a close look at how the vacuum break valve performs during the first few minutes.

-Robusto

[segrave]

Re: Upgraditis: 2-group Grimac Commercial

You need to hook up a servo to your steam nob and make it remote controled from your phone so you can bleed it from work or put it on a timer..... ;D ;D ;D now that extreme

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

---l like the idea Segrave. Its high-tech, extreme as you say, and no chance of being scalded by steam.

-Robusto

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

Update: Shes plumbed in.

After searching through various shops for various braided hoses, joiners, adaptors etc .... the Grimac is finally plumbed in.

The pressure immediately shot up to 12 bar on account of the line pressure, so I reduced the pump valve down 4 bar.

Still fine tuning, but the "no-load" (no loaded basket) pressure appears to sit at 8 bar, rising to 9 with a loaded basket in place.

Also, the pressure gauge pointer does not reset to zero, it stays at 8 bars. Is that normal?

(BTW -- Ive cheated-- no holes through the bench top yet---the braided hose slips under through a partly opened cupboard door)

-Robusto

[robusto]

Re: Upgraditis: 2-group Grimac Commercial

Another update:

Each group can now simultanously deliver 600 mls per minute without any pressure reduction. Quite an improvement from the water tank option where with both groups going pressure drops to around 4 bar.

So itll be his and hers coffees pulled simultaneously tonight.

-Robusto

[JavaB]

Re: Upgraditis: 2-group Grimac Commercial

Robusto,

Good to hear... you should get consistent pressure now..... EDIT... just read your last post and you are

The pressure reading "at rest" is strange.. It should read the mains pressure (normally about 4-5 Bar in most places Ive seen) as this pressure is applied through the pump etc when at rest.....

When the pump starts it should increase to the 9 Bar.... and as soon as it stops it should drop back down to the mains pressure (thats how I checked my mains pressure... slowly opened the mains tap and watched the brew pressure gauge.... it increased to 5 Bar.... and stopped . Sweet (the La Cimbali specs call for a pressure between 3.5 and 5.5 Bar on the supply - any more and you have to fit a pressure regulator....)

I wonder if you really have 8 Bar mains pressure??? :-/ Does it drop back once you turn of the mains (and possibly open the fitting to let a little pressure out)?