La Spaziale HX too hot - pressurestat bottomed out

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chachi
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#1: Post by chachi »

Ok, I need some help. I have a La Spaziale New EK 2 Gr that I picked up used. Machine pulled a few good shots, but since then, I have had increasing issues with too much heat. I lowered the p-stat all of the way down and it appears to be operating normally. Low set point is ~.7 bar and dead band is about .2. Pressure at both heads is 9 bar which I measured three times each.

Shots are hot, real hot. Undrinkable they are so bitter and harsh...and burn your face off hot. I have a CDNA instant read thermometer that I was registering almost 208 degrees at the elbow of a single spout PF...then I lowered it (Sirai p-stat) all of the way down, let the machine rest for a few hours and then try again. Temps settled at the numbers above, but the shots are hot and undrinkable.

The thermometer registers a little over 200 AFTER I do a couple of flushes and settles in the high 190's at the elbow of the single spout.

If a machine like this sits for a couple of hours with no use can it super heat so that no amount of cooling flushes will bring it back into spec? Or is it possible that some part of the HX circuit has a clog or something? There is a sound when running a shot that sounds as if there is some air in the system that is being pressurized out, but I don't see any air being introduced watching the water going into or coming out of the pump.

Thanks

Jason
Jason

sonnyhad
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#2: Post by sonnyhad »

Have you tried running a bit of hot water out of it, as well as a group flush?
LMWDP 437

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kajer
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#3: Post by kajer »

I have a 1GR HX machine. After 30+ mins of no use, I can hear the super heated water gurgling out of the shower screen. This will run for a good 15-20 seconds before the gurgling stops and only hot water is coming out.

This seems normal for a HX machine in my opinion. I keep my boiler at 1.2 bar normally, but I ALWAYS need to do a cooling flush just before pulling a shot. ALWAYS.

chachi (original poster)
Posts: 49
Joined: 12 years ago

#4: Post by chachi (original poster) »

Right. Cooling flushes. I am typically running 30 second flushes on BOTH heads, then I run at least three or four 10 second flushes...one every minute or so to try and cool things down...no love. I am assuming you are able to bring things to a happy place after one good long flush?

Looks like these machines don't have a typical HX either...they use steam to heat the group apparently. And here I was hoping something was clogged. :)
Jason

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kajer
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#5: Post by kajer »

Odd. One long flush should bring things in range.

You can try cheating, and using a cold portafilter if you can't seem to get the group down to a stable temp.

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HB
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#6: Post by HB »

chachi wrote:Looks like these machines don't have a typical HX either...they use steam to heat the group apparently. And here I was hoping something was clogged.
Here's a diagram:

Image
From How does La Spaziale heat water?

I've never used this espresso machine, but as a complete guess... have you checked the steam boiler water level? Or does the steam seem really wet? I wonder if the group would idle hotter as the water level increases, which often happens with old espresso machines as scale builds up on the water level sensor.

As an aside, a quickie check if the problem is grouphead idle temperature is locking in a cold portafilter for 30 seconds before pulling a shot. That will draw heat out of the grouphead and give you a better idea of the brew water temperature.

PS: For those following along, this video explains how E61 heat exchanger espresso machines work:
Dan Kehn

chachi (original poster)
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#7: Post by chachi (original poster) »

Thanks Dan,

FYI, the video is not showing, but I have seen it.

Looking at the parts diagram and the machine, fresh water comes directly from the pump to the cold water inlet on top of the "exchanger" in your diagram. What exactly happens from there is a mystery to me as the parts diagram does not have a group head diagram for the New EK.

Here is a nice tutorial on Spaziale machines, on a newer model (the ITC sounds like it would be perfect!).

After poking around a little just now I am wondering if there isn't some scale buildup inside the cold water line running through the HX that is preventing adequate flow to cool...smaller effective inner diameter/more surface area to heat? I dunno. Clearly something is up or as usual, I don't know what the heck I am doing


<edit> didn't answer your questions. The boiler level seems like it is in the right place from what I have read. Are you saying that the pressure gauge would read low in that scenario? Not sure I can wrap my head around that as the pstat would also have to have an issue as well right? I think I am not understanding you right</edit>
Jason

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HB
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#8: Post by HB »

chachi wrote:I think I am not understanding you right.
Like I said, it's a guess. If a steam boiler is filled to the tippy-top, I assume it could conduct more heat to the heat exchanger. Since old espresso machines are typically scaled, the water level sensor will be coated ever-higher with scale, resulting in a higher water level in the steam boiler
Dan Kehn

chachi (original poster)
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#9: Post by chachi (original poster) »

So, here is how this funky machine works...

It looks like the heat exchanger is actually a chamber that surrounds another steam-filled chamber. So, I am at a loss, as my scale filled tube concept appears to be out the window. Unless the water chamber is half filled with scale...although I am not sure that would make a difference. I will test the group head / cold PF tomorrow am. I don't see any other way that the group head gets cooled, other than running a flush or shot

Thanks,

Jason
Jason

chachi (original poster)
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#10: Post by chachi (original poster) »

Found another post here that looks like a great shot of a similar or the same HX here
Jason

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