Slow coffee flow does not tell you whether the boiler needs descaling. Before arranging that work, note the machine model, the exact display message and which outlet has changed. Manufacturer troubleshooting guides give several possible causes for the same complaint.
Which symptoms can involve scale?
A commercial group machine needs its own diagnosis. The Linea PB manual lists several explanations for a missing flowmeter signal, including packed coffee, obstructed tubing, pump trouble, a valve fault or a damaged meter. Its heating and temperature-probe alarms are listed separately. Repeatedly descaling a machine because it pours slowly can leave the actual fault unresolved. Linea PB, pp. 135–136
Write down whether the change affects coffee, hot water, steam or one outlet only. Include any cleaning or descaling completed just before it started. If the operator checks do not resolve it, send those observations with a service request.
What damage is documented?
Schaerer warns that its Coffee Club can suffer calcification damage when the water requires filtration and that protection is missing. A failed heater, valve or boiler still needs a diagnosis before anyone recommends replacement. Coffee Club, pp. 26 and 100
A fitted filter does not settle the question. BWT’s bestmax troubleshooting section lists several reasons a heating element or boiler may be inadequately protected from scale: an unsuitable bypass setting, exhausted cartridge capacity, an undersized cartridge or a change in supply-water hardness. Have the water-treatment provider check the existing system against those conditions. BWT bestmax, printed p. 16
Keep that check separate from the machine repair. A replacement cartridge is not evidence that an existing blockage or damaged component has been corrected.
Check the water reaching this machine
La Marzocco specifies hardness, alkalinity, total dissolved solids, pH and other water parameters separately. A TDS reading alone leaves several of those measurements unanswered. Use the requirements for your model and have the test results recorded with the equipment history. Its Linea PB maintenance form includes readings before and after filtration. Linea PB, p. 13; maintenance checklist, p. 1
Do not assign a hardness value from the cafe’s city name. BWT’s bestmax instructions use carbonate hardness and the application to select a bypass setting and read the capacity tables. The manual allows that hardness to be obtained from the water supplier or measured by titration. Ask the provider to confirm the present supply and the water delivered to the machine. BWT bestmax, printed p. 14
The water-filter selection guide explains how to compare a proposed treatment system. Filtration information here is for planning with that provider; Bay Area Coffee Service repairs the coffee machine and does not install or repair filter systems.
What a descale job involves depends on the model
For the Linea PB, checking the inside of the boilers and using a suitable cleaning product when needed are assigned to a qualified technician. The same maintenance section calls for checks of group flow, water hardness, valves and other components. An internal inspection should establish what work is needed; a noise or slow shot cannot supply that finding. Linea PB, p. 24
Some automatic machines give the operator a guided descaling program. The Schaerer Coffee Club explicitly permits operator descaling while reserving service maintenance for trained personnel. The machine calculates when descaling is due from water hardness, throughput and filter use, and the program ends with rinsing. Follow the exact manual and display sequence, including the specified product; do not interrupt the program or substitute a chemical mixture. Coffee Club, pp. 74–75 and 91
That permission does not extend to opening a boiler, working on a heating element or disconnecting a pressurized fitting. Leave internal service to a qualified technician. For routine timing, use the model-specific descaling schedule guidance and keep the completed work in the service record.
Manufacturer references
- La Marzocco Linea PB, Operating Manual V5.1 - 12/2024, pp. 13, 24 and 135–136.
- Linea PB preventative maintenance, 12 month checklist, version 2.1, May 2026, p. 1.
- Schaerer Coffee Club Operating Instructions, document 020969, V01 / 10.2018, pp. 26, 74–75, 91 and 100.
- BWT bestmax Installation and Operating Instructions, 332231-B, copyright 2017, printed pp. 14 and 16 (PDF pp. 16 and 18).