How to Properly Adjust Your Fully Automatic Coffee Machine: Explaining Grind Size, Temperature, Water Volume & Brew Pressure

With the right settings, you can get a lot out of your fully automatic machine (in addition to choosing the right beans). Whether you want to adjust the grind size of your coffee machine, fine-tune the temperature, or adapt the water volume: every change shapes extraction, balance, and aroma. Here you'll find a clear workflow and practical guidelines so that your coffee no longer comes out of the cup too bitter, too sour, or watery.

Why the right settings on a fully automatic coffee machine have the biggest impact on taste

Taste is created through extraction: how much of the soluble coffee components you have in your drink and how well-balanced they are. Settings like grind size, coffee quantity, water quantity, and temperature determine flow rate, contact time, and solubility. Even small adjustments decide whether your shot tastes sweet, clear, and full-bodied – or sharp, dull, and empty.

• Grind size: Controls flow and contact time - the most powerful lever.
• Coffee quantity (dosage): Determines concentration and body.
• Water quantity (yield): Dilutes or concentrates - but beware of "watery."
• Temperature: Influences the solubility of acids, sugars, and bitter substances.
• Brew pressure/pre-infusion: Fine-tuning for even extraction, if available.

Because beans differ in roast level, freshness, and structure, you always have to fine-tune. This is where the greatest leverage for consistently good coffee lies.

What settings most fully automatic machines offer (and where to find them)

Depending on the manufacturer (e.g., Jura, De'Longhi, Siemens EQ, Philips, Melitta), the parameters are located in different places:

• Grind size: Rotary knob in the bean hopper - adjust only while grinding.
• Coffee quantity/strength: "Strength," "Aroma" button, or bean symbol.
• Water quantity: Customize beverage ("Espresso," "Coffee," "Lungo") or ml slider.
• Temperature: In the menu "Temperature" (often levels: low/medium/high).
• Brew pressure/pre-infusion: Rarely directly adjustable; if available, in the expert menu/app.
• Flow/"Aroma" profiles: Profiles or "Intense/Aroma Balance" influence pump/flow.

Grind size (grinder): Fine vs. coarse - influence on extraction, bitterness, and acidity

Finer grinding slows down the flow, increases extraction, and leads to more sweetness and body - until over-extraction (bitter, dry). Coarser grinding speeds up the flow, reduces extraction, and emphasizes acidity - until under-extraction (sour, thin). If you want to properly adjust your automatic coffee machine, almost always start with the grind size.

• Too sour/sharp: set finer.
• Too bitter/astringent: set coarser.
• Rule: Adjust only in small increments – always while grinding.

Coffee quantity/dosage: Grams per shot and effect on body and intensity

The "strength" increases or decreases the dose (e.g., 7-12 g per shot). More grams mean higher TDS (concentration), more body, and often a more stable crema. Too much, however, can lead to channeling or taste bitter. Adjusting the coffee quantity in a fully automatic machine is key if you want intensity without overdoing the grind size.

• Higher dose: stronger, fuller - but potentially bitter if flow becomes too slow.
• Lower dose: clearer, lighter - but risk of "watery."

Water quantity/yield: Espresso, Coffee, Lungo - when it gets watery

The water quantity determines how much you dilute the shot. For espresso, 25-40 ml is common. Lungo (70-120 ml) quickly tastes flat if grind size/dose are not adjusted. Adjusting the water quantity of the automatic coffee machine: Use less water for a dense espresso taste and only extend if the shot doesn't become unbalanced.

• Espresso: 25-35 ml (strong, concentrated).
• Doppio/Extended: 50-70 ml with a stronger dose.
• Lungo: 80-120 ml - only makes sense with coarser grind and often higher dose.

Brew temperature: Which levels make sense and when "too hot" tastes bad

Higher temperature dissolves more - sweetness, but also bitter substances. Too hot can taste "boiled." In many machines, levels like "low/medium/high" are preset.

• Light roasts: rather "high" (≈93-95 °C) to extract sufficiently.
• Medium/dark: "medium" (≈91-93 °C); "high" quickly becomes bitter.
• Soft water often needs a little less heat than hard water.

Brew pressure & pre-infusion (if available): What is actually adjustable

The nominal brew pressure (e.g., 15 bar pump) is hardly directly adjustable; effectively, significantly lower pressures apply to the puck. Pre-infusion is more relevant. If "pre infusion" is available, use 1-4 seconds to wet the puck before full pressure is applied - this stabilizes the flow and reduces channeling.

Flow/"Aroma" levels and automatic profiles: How to use them correctly

Many profiles influence pump performance and flow curves (slower start, faster middle, etc.). Rule of thumb: Slower flow = more extraction, faster flow = less. For more sweetness/body, choose "Intense/Strong"; for clarity, "Balanced/Mild" - and then adjust grind size/water quantity.

How to set up your automatic machine for new beans (step-by-step workflow)

1. Check bean info: Roast level, roast date, blend/single origin.
2. Maintain machine: Brew group clean, descaling okay, sieves clear. Cleanliness prevents channeling.
3. Select baseline: medium grind, medium strength, espresso 30 ml, temperature "medium/high" depending on roast level.
4. 2-3 shots as "warm-up" shots: Establish consistency.
5. Taste and note: Sweetness, acidity, bitterness, body.
6. Adjust grind size: too sour → finer; too bitter/dry → coarser.
7. Trim water quantity: too intense/short → +5-10 ml; too watery → -5-10 ml.
8. Fine-tune dosage: More body/concentration → +1 level; less intensity → -1 level.
9. Temperature only if necessary: light → higher; dark → lower.
10. Test pre-infusion/profile (if available): 2-3 s pre-brew for an even start.

Starting recipe for espresso roasts in a fully automatic machine (Baseline)

• Grind size: medium-fine (factory setting or 1-2 clicks finer than middle).
• Strength/dose: medium to +1 (approx. 9-11 g, depending on machine).
• Water quantity: 30-35 ml per espresso.
• Temperature: medium to high (≈92-94 °C) for medium roasts.
• Pre-infusion: 2-3 s (if available).
• Profile/Flow: "Balanced" or "Intense light."

Then change only one parameter per round and taste each time.

Reading the cup profile: quick diagnostic table for sour, bitter, flat, watery

• Sour, sharp, thin body:
  • Problem: Under-extraction.
  • Fix: Grind finer; if necessary, temperature +1 level; slightly reduce water quantity.
• Bitter, dry, astringent:
  • Problem: Over-extraction.
  • Fix: Grind coarser; temperature -1 level; shorter shot volume.
• Flat, watery:
  • Problem: Too little concentration/extraction.
  • Fix: Dose/strength +1; grind finer; water quantity -10 ml.
• Sweet, balanced, syrupy:
  • Target image: Creamy texture, clear sweetness, no sharp acidity or after-bitterness.
  • Stabilize: Note grind size, dose, ml, temperature.

Why it's important to adjust the machine for each bean (roast level, age, origin)

Light roasts are drier and denser: water flows through faster, you need finer, hotter, often a bit more dose. Dark roasts are more porous and oily: easy to over-extract, so a bit coarser and cooler. Freshness (degassing) and origin (bean density) additionally shift how you need to set grind size and water quantity. Same recipe - different bean = different result. That's why you always readjust when the bag changes.

Which beans are best suited: Espresso roasts for fully automatic machines (selection criteria)

For a reliable recommendation for espresso beans in fully automatic machines, medium to dark roasted espresso blends with good solubility and stable sweetness usually work well, such as our Wilderer and Hausespresso. Crucial factors are balance, consistent roasting, and low surface oils (too much oil can clog the grinder).

Blend vs. Single Origin: Crema, Body, Forgiveness

• Blends: More consistency, strong crema, rounded profile - very good in automatic machines.
• Single Origin: Clearer origin aromas, but more sensitive; requires more precise adjustment.

Arabica/Robusta ratio: What really brings advantages in automatic machines

A moderate Robusta content (10-30%) increases crema, body, and "punch" in milk drinks. Pure Arabica often provides more complexity and sweetness, but can appear thinner. For everyday use: An Arabica-dominant blend with some Robusta is often a good sweet spot.

Freshness & storage: Why "too fresh" and "too old" can both cause problems

• Too fresh (0-7 days after roasting): Gassy, uneven flow. Wait 1-3 weeks.
• Optimal: approx. 2-8 weeks after roasting (with good storage).
• Too old: flat, cardboardy - you often have to work finer and with less water, but the limit is quickly reached.
• Storage: Valve bag, cool and dark, fill only small quantities into the hopper.

Common adjustment errors (and how to avoid them)

• Changing multiple parameters simultaneously: Always only one lever per test round.
• Adjusting grind size when idle: Only while grinding - otherwise grinder stress.
• Confusing "aroma/strength" with temperature: Strength = dose, not heat.
• Too much water for espresso: Better to extract shorter than to "extend."
• Dirty brew group/shower screen: Leads to channeling - clean regularly.
• Very oily beans: Clog grinder/brew group - prefer drier espresso roasts.
• Ignoring water quality: Too hard = bitterness/scaling; use filter or softening.
• No notes: Without documentation, you won't hit the sweet spot reproducibly.

Quick checklist: Documenting your optimal automatic machine settings

• Bean: Name, roast level, roast date, blend/single origin, Arabica/Robusta.
• Grind size: Knob position/"click" count.
• Strength/dose: Level or grams, if displayed.
• Water quantity: ml per beverage (Espresso, Doppio, Lungo).
• Temperature: Level.
• Pre-infusion/profile: Seconds/level.
• Taste: Sweetness, acidity, bitterness, body, crema.
• Notes: Water hardness, cleaning status, special observations.

Next steps: Practice the described workflow with your current bean, adjust only one parameter per round, and note everything. Deepen your understanding by specifically playing with grind size and water quantity - these are your most effective levers in everyday life.