Riello Shuts Off on High Limit???

ChasMan

I came home to a cold house last week and found no power to the burner. It was off on high limit.

What would cause a riello burner to do this intermitently?  It is a 2 year old F3 with the electronic / electric air shutter and no post purge. It is running on after the boiler drops power to the primary.



When I reset the high limit, it ran fine for a week and then did it again while I was home. The power was dropped to the primary control so power must have been moving from the air shutter to the primary control??? That is my guess anyways. I have removed the shutter and jumped it out and put the burner back in operation. Pumps are fine, water is flowing.

I took the shutter apart. Inside are, a motor, an end switch (micro switch type) and two other switches (in the crudest sence of the word), an SCR or voltage regulator (not sure) and a couple of resistors on a PCB.



In normal operation, power to the shutter is on 100% of the time, when power goes to the primary control, the air shutter opens. When the power to the primary control is shut off, I noticed that the power reapears like magic on the primary control while the air shutter closes. Thats screwed up. I think this shutter is a hazzard but not entirely sure. In any case, I dont like having just a high limit between me and and a blow off.