Below are a few different items to troubleshoot when noticing that a Slayer 1-Group is showing low pressure at the group head, assorted in order of likelihood and ease of troubleshooting.
Group Head Flow
Grab a cup that you can get a measurement with, what you want to check is the flow of the group head when the machine is in full brew(actuator to the left) mode. You are looking for about 4 ounces in 10 seconds through the group head.
If you have noticeably less than 4 ounces of water in 10 seconds then you'll want to check your inlet water flow described in "Inlet Water Flow" below.
If you get 4 ounces in 10 seconds you'll want to check your pump power setting in "Pump Setting" and then your drain tray in "Expansion Valve & 3-Way Valve"
Checking the pump setting and testing the pump setting requires a portafilter with the backflush blank inserted. With the machine on:
- Tap the circle on the touch screen to enter settings mode.
- Using the pad of your thumb swipe left to right until "Brew Pump Pressure" is present. Tap the circle to enter this setting.
- Adjusting the brew pump pressure through the touchscreen interface is accomplished by increasing or decreasing a percentage value that represents brew pump pressure relative to maximum capacity. Using the pad of your thumb, press the arrows to adjust the value in one-percent (1%) increments between “0” and “100”.
- First verify the current setting of your pump, then insert the backflush blank and test the max pressure that the current setting produces. Leave the machine backflushing and use the pad of your thumb to move the setting up at 1% increments. Verify that turning the brew pressure up or down changes the max pressure built accordingly. We do not recommend setting the pump above 35% power as this can cause the pump to wear out quickly.
If a pump needs to be set at 35% or higher to achieve 9 bar pressure you'll want to check "Expansion Valve & 3-Way Valve" section.
If the pump reaches 9 bar pressure while backflushing but not while pulling a shot, verify that you are pulling a shot in 25-50 seconds and that the coffee bed is creating enough back pressure. If the coffee bed is creating correct back pressure check "Inlet Water Flow".
Expansion Valve & 3-Way Valve
To check the expansion valve you will need a backflush blank and Phillips screw driver. The first thing you want to do is put a portafilter with a backflush blank into the group head and backflush the machine for 30 seconds. During that time watch the black relief valve in the drip tray to see if it leaks water. It will leak water once you release the backflush so it is important to run a long backflush to check for leaks. If it does leak while in the process of backflushing you will want to:
- Remove front panel
- Insert portafilter with backflush blank and verify that the expansion valve(upper brass valve) and the 3-way valve(lower black hose) aren't leaking while attempting to backflush.
If either part is leaking contact us at firstname.lastname@example.org with information regarding the issue and machine serial number.
Inlet Water Flow
This is to test and verify that the water line suppling water to the machine has enough flow. With machine off:
- Close your cold water inlet line.
- Remove braided line from Slayer 1-Group.
- Place braided line in bucket.
- Open water line and test for flow. The ideal flow rate for a Slayer 1-Group is 2 GPM(gallon per minute), + or - 0.5 GPM.
If you are receiving closer to 1 or 0.5 GPM then the issue is the Slayer is likely not receiving enough flow and you may need to replace your inline filter and softener.