Riello F3 Burner Can't Start

D107

Background: The other week it was determined that the suction line in the Roth had crimped. They replaced it with a 3/4" line (which Roth says will not solve the problem caused by the fuel additives. Carbon had built up on the head. Nozzle, o ring, filter was replaced,though there was no apparent problem with them. Got a lot of good remedies from this site and others for the suction assembly problem.

I went out to the house after the repair and noticed a little soot on outside of boiler, flue pipe and exp tank, probably from original problem. Noticed that after burner pre-purge, there was a thump (as if burner cut out after a half-second of ignition.) then after a few seconds it fired.

Got a call from my mother tonight that it's now thumping several times before starting. I told her to turn it off. Seems a little soon for the suction line to crimp. The old chronotherm thermostat has never given a problem before--I see there's another thread about very very short firing cycles. Supposedly there's a little soot in the same area as well.

Any ideas? Thermostat? Filters? This is getting to be very frustrating in a new system like this. FYI this is connected to a Buderus G115 and ST150 with R2107 control.

Thanks,

David

Weezbo

its a Valve.

D107

Thanks--any guesses which valve?

Got this advice from another site:

"First if it is a direct vent good luck. Putting that out of the way, widen the electrode gap to a sloppy 3/16. Make sure your draft (if on a chimney) is by the book, I believe it is -.03 but check the book. Make sure no air is getting in the oil it can cause brown soot on the turbulator. Too much draft can cause the soot also.This info comes from both Buderus and Riello reps."

Last reading they did a week ago was: overfire: +02, overbreech: -.04, smoke: 0, gross stack: 350, CO2: 12, 85%. Those were same readings we've always had with baffles out. Has barometric draft regulator.

I believe Roth recommends a de-aerator as well.

Thanks,

David

william_5

thump, thump thump

It Could be as simple as a loose thumb nut. This is silver in color it sits on top of a metal spacer (you must have the spacer)under the spacer is the pump coil this goes on only one way the tit on the coil must sit in to the pimple on the oil pump. this is just the start.
William

steve_26

Riello

Had a riello on a Buderus 115 last week thumping on start up running rough. set gap using a #2 phillips screw driver.sounds strange but it came from the burner rep.It needs to be wider than other burners.Also make sure the electrodes are set over the front of the nozzle correctly or you will get that thumping. adjust air to trace smoke and re-adjust to zero. cleared the one I had perfectly

D107

Seems to be solved

So, the tech spent quite a bit of time today making adjustments based on Riello, Buderus and Roth procedures:

1-with existing .50 nozzle, pump pressure raised from 145 to 155psi.

2-Baffles put back in, readings much improved: Draft OF: 0;
Draft OB: -.03, Turbulator: 0; Smoke: 0; Gross Stack: 350; air gate: 2.25

3-A de-aerator was put in, and a second oil line was added--I don't have the knowledge to describe this but 2nd line didn't go back to the tank but somewhere near burner. Not sure if that's a tiger loop or not....

I guess the electrode gap was viewed as being OK. Service company has also agreed in the future to replace the suction assembly with a hard pipe setup.

The only negative is that due to the higher pump pressure, the firing rate is a little higher than the 84mbh it's rated for. I don't know what .50 nozzle x 155psi comes out to. I'll take a guess maybe 92mbh or .65gpm? A wallie suggested --and the manufacturer's agree-- that for best efficiency --and to maintain the 84mbh-- a .40 nozzle should be installed with a little higher pump pressure. But I think this ia a good compromise for now. There seems to be enough concern in the industry over the narrow .50 nozzles without going even more narrow.

Thanks for all the assistance.