cleaning the inside of a riello oil burner

29 Dec 2020
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United Kingdom
A while ago I had a lot of help with diagnosing burner lockout problem with my worcester boiler. Thanks to that I eventually found out my oil was contaminated. I cleaned the oil with a marine diesel filter, swapped out the burner pump filter, nozzle and in-line filter, and all was good.
However, yesterday same thing happened. This time I knew what to look for and sure enough the nozzle and pump filter were clogged with algae.

I checked the oil in the tank and it seems reasonably clear - nothing like what it was before.

However, it occurred to me that the one thing I didn't do last time was purge the pipework inside the burner.

I've run the end of a matchstick around the inside of the nozzle housing and removed some gunk, but my thought is that unless it is thoroughly cleaned through the algae in the pipework are going to multiply even if the supply is clean.

Anyone think that is about right, and if so, how do `I purge the pipework? The burner is out on the bench now. I can undo the nut for the copper pipe that runs from the pump to the nozzle assembly, but it is narrow gauge pipe - I doubt blowing down it is going to do anything.

Can I flush through with a cleaning agent (for example)?
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fit a new nozzle.
as for algae... I have never seen any in 40 + years on the tools.
fit a new nozzle.
as for algae... I have never seen any in 40 + years on the tools.

Last winter I had four new nozzles fitted after repeated lockouts. Each time there was a green film on the nozzle filter. Nobody I used knew what it was. After it cut out for the last time I took it on myself to sort out. Once I found out what the parts were I checked the pump strainer. It was thick with green 'scum'. Then I checked the inline filter. It was clogged and black. When I asked one of the guys why he hadn't;t checked it he said because he thought it had already been checked.

Then I checked the oil in the tank. Took samples. Bits of black stuff floating in it. So I connected the dots and figured the pump was powerful enough to pull that stuff through the filters and on to the nozzle filter.

So then I got the marine diesel filter and run the whole tank through it.

Problem solved until a couple of days ago. Back to green stuff on the nozzle filter. I should have cleaned the tank again in the summer, so I can easily do that.

Now I've found that I can run the biocide through the burner pipes and pump without dismantling it, so I am good to go I think.
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fit a new nozzle.
as for algae... I have never seen any in 40 + years on the tools.

From what research I've done the algae/bacteria is a relatively recent thing, so you probably won't have seen it in the past. Hard to know what to believe on the internet of course but it seems to be linked to mixing mineral fuel oils with biofuel. It's apparently quite common with the boating people and there's lots of products on the market to treat it. Plus the fuel polishing which filters it out with ever finer filters. Like I did but obviously more professional. Least that's what I read.

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