Grant Combi Max oil-fired boiler problem

[petes7457]

This is a very unusual boiler fault.

Following an overnight power outage I awoke to find the above boiler spewing out thick black smoke from the flue.

After powering down and checking I found around 2 liters of unburnt oil in the base of the burning chamber that the Riello burner fires into.

I've had the oil pump assembly and injector nozzle changed as well as drying out the burning chamber and cleaning the baffles. The boiler is now running fine again.

My main concern is that this is a potential failure mode where oil was continuously pumped into the boiler without being ignited!

Anyone seen this before?

Cheers, Pete

 

[grahamtheplumber]

one thing to check is that the solenoid valve isnt letting by.the only times power supply problems do strange things to boilers is if you had a power surge,but they usually fry the control box.

 

[petes7457]

Thanks, I've already changed the oil pump and integral solenoid valve as a precaution. Control electronics seems fine.

Cheers,

Pete

 

[oilhead]

Sounds like a stuck solenoid valve in pump, which you've now changed. A power cut would/shouldhave the opposite effect to yours.

 

[Boilerman2]

Sometimes a power outage is accompanied by Low Voltage whaic can cause the burner motor to run very slow and allow oil to enter the Combustion chamber, this could be the cause i have seen this happen on the odd occasion ...it sounds like you have taken a "Belt & Braces" approach to ensuring that it shouldnt happen again. so I don't think you can do any more although it is possible to fit a relay that would cut the supply off at say 200Vac which would stop low voltage causing a problem with the burner (some control boxes such as Seimens incorporate this in their design)

 

[oilhead]

Even if burner motor does turn slowly, the oil still has to pass the solenoid, and flame would still need to be sensed to keep the valve open.
Satronics also dont run on low voltage.