Low brew pressure: Grind problem or equipment?

#1: Post by **rmag** » November 10th, 2022, 10:59 pm

I just bought a La Spaziale Dream T and have been dialing in my grind settings. I dialed in the extraction time such that extraction wouldn't start for 6 seconds and the total extraction time was about 33 seconds for 2oz. But the coffee was watery and I noticed the pressure never got into the green zone on the gauge.

I was told by my salesperson to check the machine's pressure using the back flush disc. The pressure was normal: 9.5 with the backflush disc in. So I played around with tamp, volume, and grind a bunch and eventually found a setting that impacted the extraction pressure. I was able to get the pressure into the green zone, but only at about 8.5 bars. the extraction is noticeably less watery. The problem is that it dramatically slowed down the extraction. It takes about 75 seconds to get 2oz.

Is there a way through grind/volume/tamper settings to increase the extraction pressure without increasing the extraction time? Or is there something wrong with my machine?

#2: Post by **cafeIKE** » November 11th, 2022, 10:30 am

What coffee, grinder, basket, coffee weight - both grind in and coffee weight out

November 11th, 2022, 12:25 pm

I have tried both Blue Bottle espresso and Intelligentsia. Grinder is Eureka Speciale. Basket is the standard double that came with the Dream T.

I have tried a variety of grind weights. from 14 to 19g (the Dream is a 53mm basket). In order to get the pressure into the 9 bar range, the weight needs to be about 16-17g (or super fine). But again, the extraction time balloons to 75+ seconds. If I lower the weight or make coarser, it drops to 30-40 seconds for 2oz, but then the pressure drops below 7.5-8 bar green espresso range.

I have not weighed the extracted espresso, but will do that next.

November 11th, 2022, 1:06 pm

cafeIKE wrote:What coffee, grinder, basket, coffee weight - both grind in and coffee weight out

Did another pull. I did 15 grams and made it slightly more coarse. Yielded 53g of coffee, took over 40 seconds for 2 oz, but pressure was between 5-7 bar.

#5: Post by **cafeIKE** » November 11th, 2022, 1:50 pm

Is the 2oz volume or weight?

Are you pulling into a clear cup?

Does the pull look like this

or one of these

November 11th, 2022, 2:23 pm

2oz volume in a clear cup with a measuring line

It's not quite as bad as the bottom pics, but way closer to that than the top pic. I'll try to post some videos I took

#7: Post by **Nunas** » November 11th, 2022, 2:37 pm

Could be stale coffee.

#8: Post by **Jake_G** » November 11th, 2022, 3:38 pm

This sounds like a debit issue on the machine.

Basically you have a pump that will reach the desired pressure, but the output flow rate is so low that you can't reach pressure whilst brewing a proper espresso.

What is your measured water debit? To measure this, you can either time how long it takes to reach a given volume, or run the pump for a fixed period of time (10 or 30s is common) and weigh the output. Either way works. What we are looking for is something in the realm of 4 to 8 ml/s (or g/s if you use the weight method). Just remove the portafilter and dispense water from the group into a cup and then report back.

I would guess that you are struggling to deliver around 2ml/s, based on how fine you have to grind to hit a reasonable brew pressure.

Once you determine your flow rate, we can determine if this is an issue and go from there.

Cheers!

- Jake

November 11th, 2022, 6:12 pm

My flow rate actually seems high. For 30 seconds, it's 9.8 ml/s. For 10 seconds, it's 11.8 ml/s. I got 10oz and and 4oz, respectively.

#10: Post by **Jake_G** » November 11th, 2022, 6:23 pm

Well that is most peculiar.

The only other thing I can suggest to you is to try raising the brew pressure on your OPV to give you whatever pressure you want whilst brewing.

It is quite odd that you would have 9.5 bar with the backflush disc in place and a healthy water debit but not be able to generate pressure while brewing.

The fact that you can choke your machine means your grinder is working as designed. It is baffling that you would lose so much pressure through the system while pulling a shot. But easy enough to simply raise the brew pressure until you get 9 bar (or whatever you desire) while brewing a shot that completes in a time that you'd like.

Cheers!

- Jake