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Worcester Heatslave 18/25 Oil Burner With Unstable Flame

Postby 650b » Tue Jan 09, 2018 10:50 am

Hi everyone.

First of all, it's nice to be part of a new help community. I'm not one to dive straight in requesting help and then never visit again. I'm an electrical/electronics engineer and so I have help to offer.

Problem with my worcester heatslave 18/25 oil CH boiler came about this weekend when I ran out of oil. Received the oil delivery yesterday and figured it'd be a simple matter of resetting. However, the burner (Riello RDB2.2, the clever one with the UV light sensor and clear (multi-colour) reset button) went into lock-out after 5 attempts at resetting.

I figured I need to bleed the line from the tank, odd how the tank is actually slightly higher than the pump. Still, I attempted to bleed it and as predicted, no air in the line. Absolutely nothing stopping the fuel from getting to the pump, I mean its peeing out of the bleed valve at the pump!

I reset the burner before once again resetting the boiler system to attempt another restart, did it again and again and again...

Lockout, again.

The error code (9f 855) on the boiler suggests there's an oil delivery issue, manual says "check fuel supply".

After attempting a reset once again (not before triple checking the oil line is bled), I noticed the burner started getting warm, "it must be working now, hurray". Though it stopped again, light on the burner flashing red and the f9 error came back.

Right now, I'm at a point where I can reset and it will start to burn. Light on the burner flashes amber indicating its in a pre-purge mode and then flashes green indicating normal operation. However, during "normal operation", the burner sounds stuttery like the flame is stopping and starting very rapidly. If I remove the light sensor, I can see the flame. It flashes on and off very rapidly. Eventually it will go out all together and the burner will enter back into the pre-purge cycle.

This is almost quite literally burning a hole through my brain. Am I missing something simple?

I would greatly appreciate any advice before I call a boiler guy as I already have the panel off and my tools out and I consider myself capable when armed with the correct knowledge.

Many thanks.
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