Boiler firing on second attempt

[pafos]

Riello 40 G2SX burner approx 12 years old. The problem is that the firing is random. The flame is allways established first time without problem then it either works normally or about 50% of the time the flame goes out after about 1/2 second then refires ok at second attempt.
New nozzle, control box, photocell, elctrode assembly.
What may be the cause of this ? air perhaps but from where. Tiger loop fitted

 

[Burnerman]

Take a gamble and replace the coil that sits on the oil pump - they are notorious for failing. Also make sure that the metal retaining bracket, over the coil, is in place - it needs that too.
John

 

[pafos]

HI John---Thanks for the reply. I take it you mean the solenoid coil.
As an electrical engineer I have had many dealings with solenoid coils in one form or another but never come across one that causes the valve to not work properly. Either they are ok or not but for the sake of £9 I will certinly get a new one and see what happens.
Oonce again many thanks and a very happy Xmas to you.
Peter

 

[Tibbot]

Riello 40 G2SX burner approx 12 years old.
New nozzle, control box, photocell, elctrode assembly.
What may be the cause of this ? air perhaps but from where. Tiger loop fitted

Hope you've not replaced the above list for this fault alone. If so, don't think I've had to use this much on all the R40's I've visited. Usually very reliable.

 

[pafos]

Hi----This "fault" has been with me for months now so it was a process of elimination as I cannot positively identify what is wrong. Agree they are very reliable with 12 years perect service but now there is a problem that I cannot as yet solve hence this question in the forum.
Peter

 

[martineire]

I take it you mean the solenoid coil.
As an electrical engineer I have had many dealings with solenoid coils in one form or another but never come across one that causes the valve to not work properly. Either they are ok or not

Solenoid coil can be very tempermental and work when they want and then fail when they heat up and work again later when cool. Cheap and worth replacing before you start replacing expensive parts and then discovering it was the coil in the first place

 

[pafos]

HI good folks.
Continuing my quest for the solution to the firing problem I replaced the solenoid coil as suggested but no change. A good friend of mine is a "boiler man" and suggested that the solenoid needle valve sometimes went faulty so have just replaced that but again no change.
To recap burner fired for about half second then flame goes out. Usually starts again on next attempt. This occurs about 60% of the time. I have noticed that when the burner fires up OK at the first attempt I get a nice gentle "whooosh" as the oil ignites but when the fault happens I get a fair old "wurmph" that rattles the casing a bit.
Any more ideas welcomed

 

[Burnerman]

Look very carefully at the condition and settings of the electrodes if you get a noisy start up...they may just be too far back from the nozzle.
I'm wondering if you are getting a chuff of fume, snuffing out the flame for an instant.....
Presumably the boiler internals are clean?
John

 

[oilhead]

John assumes the boiler internals are clean, are they?
When was the nozzle last changed?
Is the photocell clean? I find these less reliable than Riello coils, and cheaper. Also re-ignition is first symptom of P.C. problem.
Is pump filter clean?
Does the pump produce full pressure at first attempt? It is 12 years old.

 

[WDIK]

if ignition is achieved, lockout is due to failurre to detect flame

 

[pafos]

Look very carefully at the condition and settings of the electrodes if you get a noisy start up...they may just be too far back from the nozzle.
I'm wondering if you are getting a chuff of fume, snuffing out the flame for an instant.....
Presumably the boiler internals are clean?
John

Electrodes brand new and set exactly to Riello dimensions. I wondered my self if the flame was being "snuffed" out somehow but what would be wrong to cause this effect.

John assumes the boiler internals are clean, are they?
When was the nozzle last changed?
Is the photocell clean? I find these less reliable than Riello coils, and cheaper. Also re-ignition is first symptom of P.C. problem.
Is pump filter clean?
Does the pump produce full pressure at first attempt? It is 12 years old.

Internals clean. Nozzle approx 10 months old but this problem not changed when new nozzle fitted. Photo cell brand new and clean. Pump filter is clean. What do you mean "P.C Problem" ? OIl pressure applied to air damper 100% open in 2 seconds hence assume same pressure is getting to nozzle.

if ignition is achieved, lockout is due to failure to detect flame

Burner does not go into lockout it just does another purge then fires again. Remeber this has a new control box and photocell.

I would like to persue the "snuff out" theory. Would it be in order to remove the combustion chamber inspection cover and remove the baffles then have an actual look at the flame for a few seconds or is this too "dodgy"?
Thanks to you all for your input in this matter.

 

[Burnerman]

If you take the boiler top off and look at the flame, you do run the risk of getting a face full of fumes and soot, etc.....
If your boiler has a balanced flue, try running the thing with either the burner box off or the snorkel tube or whatever it has removed - in other words let the burner take in air from within the room.
Check that the burner purges for at least 6 seconds before attempting to ignite.
After this, its time for an oil pump pressure check, and a flue gas analysis if you haven't already had this checked. You may be down on pump pressure, or even an excess of air could be causing this.
John

 

[pafos]

If you take the boiler top off and look at the flame, you do run the risk of getting a face full of fumes and soot, etc.....
If your boiler has a balanced flue, try running the thing with either the burner box off or the snorkel tube or whatever it has removed - in other words let the burner take in air from within the room.
Check that the burner purges for at least 6 seconds before attempting to ignite.
After this, its time for an oil pump pressure check, and a flue gas analysis if you haven't already had this checked. You may be down on pump pressure, or even an excess of air could be causing this.
John

HI John---Boiler is wall mounted balanced flue. Have run it direct from room air simply by removing front panel as this exposes the complete internals with air intake exposed. Purge lasts for 12 seconds as per Riello spec. My Boiler man is due a visit for the annual service so will ask him to do a complete check on all the parameers. It has always passed with flying colours in the past. I will mark the position of the air regulator setting (for reference) then reduce the air a little and give that a try out.

 

[pafos]

Some news---I decided to have a good look at the burner so I removed it and did the following to it.
Moved the electrodes 0.5mm further forward.
Cleaned the blast tube as It had a sooty deposit inside
Removed the nozzle, dismantled it, no dirt found so reassembled.
Removed some slight carbon build up on the electrodes and insulator
Reduced the air supply very slightly

Now all ok and no loud start up noise (so far). Now as an engineer I realised that I should only alter one paramenter at a time when fault finding BUT I do not have all the time in the world at the moment. My gut feeling is that it was cleaning the blast tube or moving the electrodes has changed the scenario.
Will advise again if problem returns.

Thanks to everyone again for the help