Oil burner not cutting off.

me4many

I have oil fired central heating in a small cottage. There are seven rads in total all fitted with trv's .Boiler is a firebird which is probably 15 or more years old with a new riello burner.

I've noticed that the burner doesn't turn itself off at all during a cycle ie if I put it on for one hour it runs continuously for that hour.

The controller on the boiler/burner is set at 75 deg.

The rads do heat up ok but I think they used to get hotter..

Q: Why does the burner run continuously and not cut in/ out several times ( like it used to) during that hour.

Thanks in advance for any help..

meercat

https://www.boards.ie/discussion/2058220362/oil-burner-not-cutting-off

Perhaps the thermostat is faulty or set too high. Try turning it down to 50

Wearb

Could be that new burner is way underfired for the boiler.

Post full details of both.

If boiler stat was faulty then high limit stat should be tripping, unless (as above) the burner output never catches up with demand.

jimf

sounds to me like you have the wrong burner fitted or else its way underfired

if the new burner has a short blast tube this may confirm what ive said above

rads not been as hot is also a bit of a giveaway

maestroamado

https://www.boards.ie/discussion/2058220362/oil-burner-not-cutting-off

Turn it down to 60/65 and bring up gradually until you think ads feel about what you think right temp... the numbers on these stats mean nothing... trial and error until it feels right....

me4many

Boiler details...

Firebird..Popular / Boiler house S 90

Heat output range 21kw - 26kw

Max operating pressure 3 bar.

Burner : Riello 40

Hope that info helps..

Thanks.

Wearb

https://www.boards.ie/discussion/comment/118242414#Comment_118242414

Do you have the burner setup details from the installer? Like pump pressure, nozzle size, co2 etc.

BTW, what was the reason for fitting a new burner?

John.G

I have the exact same 16 year old boiler in a Heat Pac. Mine came with the burner set to 21kw.

I had a unusual experience about 10 years ago, the boiler started running continuously as well late one night, I went up to the attic and found the ball cock making up continually to the F&E tank, I shut the boiler down and shut the ball cock and the whole system drained down, I have a suspended floor and I fairly quickly found a 1/2" tee almost completely backed off which was obviously the leakage point.

Not saying you have the same problem especially if the constant firing is happening since burner renewal, also if you had a leak with a sealed system then the boiler (hopefully) would have tripped on the hi level stat before the system ran completely dry.

It would require a constant leak/makeup of ~ 5/6 LPM to keep a 20kw boiler firing continuously assuming no heat to system.

jimf

https://www.boards.ie/discussion/comment/118242414#Comment_118242414

that boiler should have a .60x80h nozzle set to about 8.5 to 9 bar pressure

if the pressure is set way too low as i have often found then there is a good chance that the burner is not giving the required output

John.G

What, in your opinion, would be the minimum before flame out or what ever?. If you assume that the house heat load is ~ 10kw then the burner pressure would have to be as low as ~ 2 bar to give a boiler output of 10kw, is combustion possible under these conditions?

me4many

I don't know burner set up..

Plumber says that burner is preset..

Reason for chance: water got into the oil pump and as the burner was old it was suggested it better to just get a new burner complete.

Thks..

jimf

https://www.boards.ie/discussion/comment/118242721#Comment_118242721

min pressure where kerosene will atomise properly 6bar is as low as i have ever come across

jimf

https://www.boards.ie/discussion/comment/118242832#Comment_118242832

was the water removed from the oil tank and oil line and filter etc all blown out and cleaned

i would presume it was otherwise new pump would have failed already

how long ago was burner changed

me4many

Yes using new tank and new oil..line cleaned and new filter fitted.

New burner fitted a few days ago.

Thks.

John.G

https://www.boards.ie/discussion/comment/118242903#Comment_118242903

Mine has the (original) Riello G5X Burner and had and has a 0.6X80H nozzle. Don't know if the OPs replacement is the same (unlikely making them now) but the Riello RDB2.2 had a range from as low as 15kw so maybe his replacement burner came set to 15kw but even at that except he has a huge number of rads, the boiler should still be cycling once water contents up to temperature and should still give ~ 12kw at 6bar oil pressure. Should get installer back because normally, with any outside air temperatures, the burner if set to 21kw should start cycling after 20/35 minutes like mine does with 10 rads from a cold start each morning.

jimf

https://www.boards.ie/discussion/comment/118243094#Comment_118243094

sounds exactly like my own john 30/35 mins

jimf

https://www.boards.ie/discussion/comment/118242923#Comment_118242923

def get installer back something small

turn the stat to the lowest setting and see will eventually turn of

how many rads and house size

maestroamado

https://www.boards.ie/discussion/comment/118242923#Comment_118242923

Think of the dial on your stat which you say is say is 75deg... Think of it as you think of the temp dial on an oven and adjust per your needs... your problem is very simple just adjust... Everything is preset except the temperature as different people have different heat requirements...

me4many

Thanks for all the help..

I should have answered earlier that it's a small cottage with seven rads..

Thks

Wearb

You need to get somebody out to match the settings on your new burner with the boiler and check that the burner head is at least somewhat compatible. (Also tell them of your previous water problem, so they can do a few extra checks)

This person needs to check boiler manual for: Pump pressure, nozzle size and pattern, electrode settings, CO2, CO and flue temperature. Also needs a smoke pump to check for smoke. So for the above, he needs a Flue Gas Analyser, a pressure gauge and smoke pump.

From the above you can see how remiss it was of the plumber to just slap in a new burner out of the box.

From there you can then (with confidence in the setup) start to track down other problems ... if they still exist.

meercat

Check again if the thermostat actually turns the burner off.

John.G

Yes, just keep turning down the boiler stat until the boiler cuts out and post its setting, looks like that burner for whatever reason is only outputting 5/6kw with 7 rads.

Wearb

Is there white "smoke" from it when running?

me4many

Update..

I checked the burner running this evening...

For no obvious reason ( to me ) the burner seems to have "corrected " itself and is now coming on/off about every five minutes . I'll time it more accurately over the next few days. .

The stat on the boiler was set at 75deg..

I have now moved that to 70 and will monitor how that goes.

Thanks for all the help and interest .

John.G

Wonder was it actually firing 100% previously or just running the fan continuously with very short firing times, if it re occurs keep an eye on the flame peephole or listen as you will certainly hear a Firebird firing on/off.