Saga of the Sine 18 T3 boiler.
Way back I had a callout to attend this boiler. The boiler was peaking at 65 degrees C regardless of boilerstat being set to maximum.
Pressure differential unit was the culprit. As the system water heated up, differential unit spindle retracted into the unit, cutting off the burner. System water cools and the differential spindle ejects and burners fire to reach the 65 degree ceiling temperature.
Chemical were introduced into the system as two of the rads were cold in the middle. Cleaner the system got, higher the system temperature rose. Now the boiler started to overheat and cut out on the overheat stat.
Put the multimeter on the mod coil to note a drop in terminal voltage. This decrease of voltage was not rapid enough, leading to boiler shutdown. This is when I noticed the broken seal on gas quantity regulator. Burner pressure was taken, which was nearly 13mbar. This was reduced to correct burner pressure.
If I remove the mod coil, I can manually modulate the burner (without any lag)
With mod coil in place, voltage at mod coil starts to drop but there is a distinct lag before the burner pressure starts to decrease. At 10mb, the boiler will lockout on overheat. Reducing burner pressure to 8, no lockout occurs but hot water temperature rise starts to suffer.
Clearly, the mod coil is the culprit as there is a delay between call for burner pressure reduction (voltage drop at the coil terminals) and actual reduction of burner pressure.
Does anyone know the function of the grub screw on the chamber at the base of the mod coil? In the past I have opened this chamber to see some kind of oil (silicon?) in it. It would appear to be a damper of some sort.
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No sooner had I put the post up, there were three viewings of the post. How is that possible? Also the clock is one hour behind.
Way back I had a callout to attend this boiler. The boiler was peaking at 65 degrees C regardless of boilerstat being set to maximum.
Pressure differential unit was the culprit. As the system water heated up, differential unit spindle retracted into the unit, cutting off the burner. System water cools and the differential spindle ejects and burners fire to reach the 65 degree ceiling temperature.
Chemical were introduced into the system as two of the rads were cold in the middle. Cleaner the system got, higher the system temperature rose. Now the boiler started to overheat and cut out on the overheat stat.
Put the multimeter on the mod coil to note a drop in terminal voltage. This decrease of voltage was not rapid enough, leading to boiler shutdown. This is when I noticed the broken seal on gas quantity regulator. Burner pressure was taken, which was nearly 13mbar. This was reduced to correct burner pressure.
If I remove the mod coil, I can manually modulate the burner (without any lag)
With mod coil in place, voltage at mod coil starts to drop but there is a distinct lag before the burner pressure starts to decrease. At 10mb, the boiler will lockout on overheat. Reducing burner pressure to 8, no lockout occurs but hot water temperature rise starts to suffer.
Clearly, the mod coil is the culprit as there is a delay between call for burner pressure reduction (voltage drop at the coil terminals) and actual reduction of burner pressure.
Does anyone know the function of the grub screw on the chamber at the base of the mod coil? In the past I have opened this chamber to see some kind of oil (silicon?) in it. It would appear to be a damper of some sort.
++++++++++++++++++++++++++++++++
No sooner had I put the post up, there were three viewings of the post. How is that possible? Also the clock is one hour behind.
