Does anyone know why an Riello RDB boiler would start pluming black smoke?

[John.g]

If the pump hasn't been run dry due to a frequently empty tank then it may be ok, could possibly be partly sticking solenoid, on my GX5 burner there is a very sharp distinct click when the solenoid is energised closed after the purge period. Maybe worth fitting a new nozzle and getting the pump pressures checked by someone before spending a fair bit of money.
[automerge]1590446119[/automerge]
One other item, on some of these modern burners I think that they are also fitted with a air intake shut off damper opened with a hydraulic ram by the pump pressure, might also worth checking this out in case its not opening fully and throttling the air.

 

[SJB060685]

John the hydraulic damper you mention is found on older Mectron burners, not the RDB this burner is. Firebird did install a damper if you will on BF snorkels, until they realised it caused my problems than answers. The type of design you mention is also found in some Riello two stage commercial boilers but no modern domestic PJ burner does this that i know of.
Smoke and soot emissions are down to either an excess of air affecting flame pattern and causing combustion issues, or more commonly an air deficiency, resulting in high CO2 and smoke emissions. Knowing that one then needs to think of all the things that could cause this.

 

[gilt279]

I had a riello burner on a grant combi boiler. A metallised sticky label fell off of the heat exchanger, when it got hot, and landed on the burner air inlet, restricting the air, and suddenly causing sooty smoke.

 

[John.g]

Attached is a interesting piece re oil pumps in general, I can now see where the Danfoss regulating valve works in the "opposite" way to the Riello, see post #11, above, for Riello Pump schematic.

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

Check Out Plumbing News!

 

[SJB060685]

Have a look through the whole article John, I've had it saved as a PDF on my ipad for some time. Its very interesting and gives you lots of information from different pump type schematics through to how resistance is generated in the suction line and a whole lot more.

 

[Stigster]

Excellent paper that is! Thanks for sharing.