Blocking errors versus lockout errors

What is going on

There are two kinds of error on this boiler and they act differently, so it helps to know which one you are looking at. A blocking error clears by itself once the cause goes away, and the boiler restarts on its own. You can spot it because the display shows the blocking symbol ahead of the code. A lockout error stays put until the cause is fixed and someone presses the Reset button. If either one keeps coming back, that is a sign something real is going on, and it is time to call a qualified service technician.

Likely causes

• Temporary condition such as low water pressure, high temperature or a sensor reading out of range (blocking)
• A safety fault that needs a manual reset, for example a failed ignition (lockout)
• Repeated error 108 with frequent refilling points to a water leak in the system
• An underlying fault that clears and returns, so the same code shows up again and again

Check in this order

1. Look at the display and note whether the blocking symbol appears before the code. If it does, the boiler restarts on its own once the cause clears.
2. Write down the code before you reset anything, so you can tell a technician exactly what you saw.
3. For a lockout, find and fix the cause first, then press Reset. Resetting without checking just repeats the lockout.
4. If a blocking error continues, call a qualified service technician.
5. If error 108 keeps happening and the system needs repeated refilling, turn off the boiler and its power, shut off the main gas valve, and have a technician check for water leaks.
6. Check the system pressure gauge and look around the piping for wet spots or drips while you wait.

More boiler guides

• Access the low voltage wiring connections
• Blower not running
• Blower runs at high speed with burner off
• Boiler bangs or hisses; Lockout 81 delta T
• Burner not running on a call for heat
• Check inlet gas pressure at the boiler