Riello burner issues (new pump needed?)

Bookpaul

Hi all,

I've been pulling my hair out over our boiler. It's a riello g3b burner from what I can tell and hasn't started properly for the last few weeks. When I start it up the fan spins up, but the flap at the side doesn't raise to let air in. Fan keeps going and After the few seconds the electrodes fire for a few seconds and then it cuts out. It doesn't make nearly as much noise as it used to either, which makes me think the pump might be gone. We have more than enough oil and I've bleed it, but the flap not lifting and lack of noise makes me think it's the pump.

I've seen people mention the capacitor being an issue, would that cause the pump to fail but let the fan motor run okay? I've been thinking of getting a new pump for it but if it could be a capacitor problem that'd be handier, or it could be something else altogether?

If anyone has any ideas I'd really appreciate it, would love to sort it before the cold starts.

John.G

I think that "flap" is actually a hydraulic damper, it may be sticking/jammed, I would first check it out before installing a new pump, if you disconnect it and open it manually then fire the boiler and see if its operating normally this will give you some indication of what's wrong, you can then decide to get someone to check out the oil pressure or the hydraulic damper may just need a new oil seal.

perry stanley

Aaaaah you might want to check the plastic coupling between pump and fan. The fan will work but if coupling is kaput pump no spin, ...no fuel and the ram will not operate. Try that then you can start looking elsewhere if its (coupling) good.

jimf

once you are 100% happy you have oil at the burner there is a good chance the pump is goosed


but I would not go replacing the pump without first checking the cause of failure if its water contamination from filter/tank then you will be back to square one within hours


anyway when changing pump you will be interfering with the set up of the burner and this is why I would bite the bullet and get somebody with the expertise and equipment to check it over for you


you say the burner doesn't sound as loud when you do try to fire it up with the damper in the closed position it will sound different anyway


what area are you in maybe we can recommend somebody for you

Bookpaul

Thank for the help all. Had another crack at it today, took off the pump and checked the coupler, seems like it's intact and pump was a bit stiff (it would turn but locks up randomly needing more force to keep turning it). Pump filter was clean and no signs of rust anywhere. Had the tank emptied in case of a water issue. I've tried manually opening the damper on the side and starting it, goes through the usual motions drawing in a fair bit of air, and then cuts out after electrodes fire for a few seconds. Also checked cad detector with multimeter and that seems fine. I can hear the electrodes arching so assuming that's not an issue.

Would the damper not raising be any indication of if it's a pump pressure issue or control box or am I looking at the wrong thing? I'm half tempted to just buy a pump but worried it'll still be the same with a new one.

K.Flyer

I know you said you bled the pump, but have you checked the fuel pipe filter to make sure its clean and also disconnected the fuel line from the pump and checked for a strong flow of fuel.

jimf

damper not opening means pump is producing zero pressure


the riello 3gb pump produces 2 pressures

a wash pressure up to about 4 bar which should open the damper

b run pressure for kero around 9bar


seems like your pump is ballcocked

whizbang

I came across a very similar issue with one a few yers ago.

The drive key that connects the shaft to the gearing was worn in a peculiar way, to cause it to push out against the cover plate.
It would usually turn by hand ok, but if you ran the motor, the key just jammed up.

John.G

jimf wrote: »

damper not opening means pump is producing zero pressure


the riello 3gb pump produces 2 pressures

a wash pressure up to about 4 bar which should open the damper

b run pressure for kero around 9bar


seems like your pump is ballcocked

Just as a matter of interest, in a healthy burner, is there much difference between the pressure just before the solenoid valve opens and the actual pressure when the burner is firing?

jimf

John.G wrote: »

Just as a matter of interest, in a healthy burner, is there much difference between the pressure just before the solenoid valve opens and the actual pressure when the burner is firing?

in the 3gb up to ignition a healthy pump will be producing up to as high as 4/5 bar on coil energising it will then change to set run pressure


on the rdb burner wash pressure will be lower up to about 1.5/2 bar


with a gauge attached to the pressure port a pump producing wash pressure isn't necessary able to produce run pressure as sometimes the keyway on the pump goes tits up thus slipping when higher pressure needed

another thing to be aware of is a pump producing wash pressure and jumping to run pressure without igniting can mean just a blocked nozzle

jimf

whizbang wrote: »

I came across a very similar issue with one a few yers ago.

The drive key that connects the shaft to the gearing was worn in a peculiar way, to cause it to push out against the cover plate.
It would usually turn by hand ok, but if you ran the motor, the key just jammed up.

common enough issue

John.G

jimf wrote: »

in the 3gb up to ignition a healthy pump will be producing up to as high as 4/5 bar on coil energising it will then change to set run pressure


on the rdb burner wash pressure will be lower up to about 1.5/2 bar


with a gauge attached to the pressure port a pump producing wash pressure isn't necessary able to produce run pressure as sometimes the keyway on the pump goes tits up thus slipping when higher pressure needed

another thing to be aware of is a pump producing wash pressure and jumping to run pressure without igniting can mean just a blocked nozzle

Thanks, but how sophisticated is this pump control pressure?, I just always thought that the sequence may be …. fan/pump start rotating, as soon as the pump pressure is high enough then the hydraulic ram will start to move and eventually will be fully open (at the end of its travel) well before the purge period of 12 secs has elapsed, so now you will have a pump just circulating oil through its by pass until the solenoid valve opens and allows oil to flow through the nozzle, if this is how it works then I would have thought that because the oil pressure is just controlled by a simple spring loaded plunger? that some pressure difference might be seen between just before the solenoid valve is energised and the running oil pressure.

jimf

John.G wrote: »

Thanks, but how sophisticated is this pump control pressure?, I just always thought that the sequence may be …. fan/pump start rotating, as soon as the pump pressure is high enough then the hydraulic ram will start to move and eventually will be fully open (at the end of its travel) well before the purge period of 12 secs has elapsed, so now you will have a pump just circulating oil through its by pass until the solenoid valve opens and allows oil to flow through the nozzle, if this is how it works then I would have thought that because the oil pressure is just controlled by a simple spring loaded plunger? that some pressure difference might be seen between just before the solenoid valve is energised and the running oil pressure.

not very sophisticated at all by my understanding as the wash pressure can vary from 1bar to 5 bar from burner to burner I have even seen them not open damper and when coil is energized damper and ignition all kick off at same time


im open to correction but I think the valve is normally open until energized then closed to divert oil to the nozzle port not that it makes any difference once it works as it should and gives heat

ive never noticed a variance of pressure myself john but will look in more detail over the next few burners I service

John.G

jimf wrote: »

not very sophisticated at all by my understanding as the wash pressure can vary from 1bar to 5 bar from burner to burner I have even seen them not open damper and when coil is energized damper and ignition all kick off at same time


im open to correction but I think the valve is normally open until energized then closed to divert oil to the nozzle port not that it makes any difference once it works as it should and gives heat

ive never noticed a variance of pressure myself john but will look in more detail over the next few burners I service

That would be interesting, my own nearly 15 year firebird fitted with a Riello rbl 7398 171 t pump has no hydraulic damper and the fan/pump draw 99 watts on pre purge and 108 watts with energised solenoid. Attached is interesting, it also shows a 2 stage burner, 8 bar/20 bar, I presume this can be fitted to a boiler to give ~ turndown to 50% output and would also need fan damper modulation?.

jimf

riello also have a version john fitted to a lot of boilers used as an easy start where gas oil would be the dominant fuel


look up riello g20