Boiler not lighting

[Dave Baker]

Oil Ch boiler, Boulter Camray 2 model 51/67 circa 1990 vintage with a Riello

40/3BM burner. It failed to light this evening for the first time. The reset button has a red lockout light which glows if the burner has tried to fire but failed and this was indeed glowing. Pressing the reset to try again had no better effect.

CH pump is running and everything else looks normal. My first thought is that as the boiler has tried to fire then the water thermostats and zone valves must be ok and this is an ignition problem. Looking at the fairly vague manual there are electrodes which should be adjusted to a 3-4mm gap. It would help if it said a bit more about where they are! Alternatively maybe the photo resistor is not detecting the flame properly.

Too late to do anything tonight but tomorrow I must get the tools out. Can anyone suggest a logical sequence of checks to make? I have a DMM and all necessary tools and it looks fairly simple in there compared to modern boilers. Sod all to go wrong or that's what I'd been hoping anyway since I moved in here in 2012.

On the right hand side of the burner there's a spring loaded iron air flap plate and this had a mist of oil on it with a little accumulated on the base plate of the boiler casing below. It seems to be leaking from a brass cylinder about 1 inch in diameter with a small diameter (circa 4mm) brass oil feed pipe running to it. Not sure what this is or what it does.

What's the spares situation with this model if it requires any? I'd much rather retain an old simple boiler which is maybe not so efficient as modern ones than save a few quid in oil costs and get a modern complicated beast which costs a fortune to maintain. With oil so cheap nowadays it costs bugger all to heat the house anyway. Less than £400 a year.

[Martin Brown]

Do you hear a spark and does the sprayer sound like it is going?

They will be somewhere in front and just below the sprayer.

Sooted up photocell sensor is the first easy thing to check. But you should investigate why it has sooted up too. It could be a symptom of bad things going wrong with the exhaust flue (or more often just gale force winds blowing from the wrong direction).

All mechanical moving parts and some electrical ones wear out. When was the spray head last changed? Whole unit last serviced?

Are you describing the spray head or the solenoid here? Solenoid failure results in no oil going to the spray head.

I once had a subtle fault where the boiler would never start after an overnight spent off due to a tiny leakage that triggered "bad flame".

Dunno. Spares for mine 70's vintage seem to be fairly easily available many decades after it was installed. It is due for replacement now.

[Michael Chare]

Look for burner spares on the Riello web site. - or elsewhere if you know a part number. You might also be able to download the burner manual.

Make sure oil is getting to the burner, not water. Paper filters will block up if not changed regularly.

Fluids leaking onto the control box was another problem I read about.

You will see the electrodes if you remove the burner from the boiler.

You should be able to just hear the electrodes when they fire, particularly if the burner does no light.

I suggest you post a picture of the leak. There should not be any leaks.

[Martin Brown]

Stating the obvious here but isolate the mains from it first. You really don't want the thing firing when you have it out on the floor!

Mine you certainly can hear the spark arcing and in the dark see it.

Leaks are worrying - although it could be just accumulated spray that didn't ignite (also capable of sooting up the photocell).

A picture is definitely worth a thousand words.

[Michael Chare]

My RDB Riello would not start when it was not in the boiler. I don't know why, maybe to much light on the photo cell. But yes, make sure power to boiler/central heating system is off first.

[Robert]

+1 Leaks which result in significant oil accumulating can be very dangerous if it then ignites.

[Martin Brown]

It is surprisingly resistant to that unless in spray/vapour form although I would not want to ever have it happen in my house.

In Belgium I was looking for rented property and one place we looked at had about 1" of standing kerosene in the basement with the boiler there still running after a fuel spillage on delivery (basically the fuel stop didn't). After finding this unusual "feature" we left PDQ.

[Dave Baker]

Right, I've taken the burner out, the electrodes are still correctly adjusted according to a pdf I downloaded, the spray nozzle looks ok and the gauze filter in it is completely clean but it is at least 3 years old. I gave the photocell a wipe but it made no difference.

Zone valves are working fine although I'm not sure they would stop the boiler firing until at least the water inside it was hot enough to trigger the thermostat.

Boiler has not been serviced for the 3 1/2 years I've been here at least. Dunno about before that.

When I first switch on at the wall not much happens and then the lockout lamp glows or sometimes it glows immediately. When I press the lockout button to reset it there's a pause and then a tizzing sound which I guess is the electrodes firing but still no ignition.

I think I'm stumped unless someone can suggest something. When my old gas boiler at the last house failed it was always the thermostat which was an easy replacement. Could it be the same here or does the electrodes sparking rule that out?

I could stick a new spray nozzle in I guess but if it's electrics I'm out of my depth unless I have specific terminals to test for voltage.

[Martin Brown]

It is probably worth getting a man in to fault find it then and replace the nozzle at the same time. They have a limited working life and TBH I can't see the difference between an unreliable one and a new one. I can easily hear the difference as a much quieter flame after replacement.

Sounds a bit like no fuel getting to the pump but guessing at the fault could result in ending up with a bunch of irrelevant spares.

If the thermostat fails mine won't have power at all. Mine is so old it is all relay based logic with a single board interface to the LDR.

It might be worth checking the LDR is OK with a multimeter if you can do it safely but it is only an outside chance that it has failed.

TBH I think you are better off getting someone in and watching how they tune it up. If it hasn't been serviced for that long it could easily be a build up of soot in the baffles causing trouble.

[Dave Baker]

Right, I think I'm getting closer. The burner motor isn't running which means neither the fan blower nor the high pressure oil pump are working. There's a big capacitor wired to the motor which could be the problem or of course the motor itself. My DMM doesn't do capacitance. How to proceed?

[Martin Brown]

Assume the motor start capacitor is caput and get an equivalent matching one from the likes of Rapid online. It must have the same capacitance and at least the same voltage rating or better.

I know from experience that a "dead" capacitor may well measure OK even if your DVM does capacitance at low voltage and current it is only only under serious load starting the motor that it misbehaves.

You still probably ought to have the thing serviced. If the exhaust baffles have not been vacuumed for three years then they will be in need of some attention even if they are not a problem yet.

[Michael Chare]

Make sure that the shaft can rotate easily.

I suppose you don't really know if it is the motor+capacitor or the control box. You may be able to see if there are any volts on the motor terminals. Also you may be able to check the resistance of the motor windings.

You may find that you can buy a complete burner replacement for not much more than the cost of the parts.

[Dave Baker]

Thanks. I did most of this as a first step yesterday. By pulling back the air flap I could just get a screwdriver on to the fan impellor on one end of the motor and that turned easily with a small resistance I considered normal given it's driving the 100+ psi oil pump at the other end.

All four motor wires had infinite resistance to earth and zero to each other so I'm happy with that. I didn't test for voltage to the motor given wiring diagrams are not my strong point but it's getting past the two thermostats at least and down to the control box or the electrodes wouldn't be trying to ignite the non existant fuel.

I googled a method of testing a capacitor just using the resistance scale on a DMM and it didn't behave as indicated so I've ordered one off Ebay for a tenner.

I do love the simplicity of this boiler. Even more straightforward than my old 80s gas boiler in the last house. Now I've had it all apart and sussed out what does what I see no reason why it shouldn't run for decades more with the occasional spare. It might use a bit more oil than a modern condensing one but this house is so cheap to heat anyway and oil is now less than 40p a litre. I'd far rather have something designed to last for ever than this modern crap which breaks every few years and costs a fortune to fix.

[Michael Chare]

Are you able to check whether the control box is supplying volts to the motor when it tries to start?

Oil boilers are not to difficult to maintain. They do need regular maintenance. An oil pressure gauge and a smoke measurer are not to expensive. A CO2 meter is more expensive but is really needed to tune the boiler properly.

[Dave Baker]

If someone can tell me which terminals to test between from the wiring diagram I could. Diagram 7.2 in the pdf below. I have no idea which of the 4 motor wires should have voltage or how much. Electrickery is little more than arcane magic to me and being colourblind does not effin help! Give me a nice simple high specification race engine to build any day.

I have however verified the actual motor wiring to the diagram and everything agrees. Trouble is when the control box is refitted you can't get to the terminals other than from underneath but I'll find a way.

[johnjessop46]

The brass cylinder is a hydraulic ram to open the air flap when the oil pum p delivers pressure. It and the flap should be dry. If it weeps droplets of oil are sucked into the air intake and burn on the nozzle head, sooting it up. There are two length variants on the ram so make sure you get the righ t size replacement. I understand further down the thread that you suspect a failed capacitor (c ommon fault 4 microfarad) Alternatively you might have an oil leak from the pump shaft. This washes the grease out of the pump end motor bearing and t he motor/pump get "lumpy" to turn, often refusing to start turning. The bea ring is a 6202 C3 shielded version. A failed photocell can tell the burner a flame is present before it should be so the control goes straight to false light lockout without trying to st art. You can check this by removing the photocell and pressing the reset. I recall writing an extensive description of fault finding/servicing oil bo ilers in here a few years ago. A search might throw it up.

[Michael Chare]

With regard fig 13 on page 17, you could measure between 3 and 6; 3 and

7; and 3 and 9. However I don't understand exactly how the control box works, so I don't know what each terminal is for.

You can buy a complete 2nd hand burner on ebay for £120.

[Dave Baker]

Between 3 and 6 I get 240v, between 3 and 7 I get 50v as it says on the diagram and the same 50v between 3 and 8. I can't reach terminal 9 with the control box in place without running a separate wire out of it but I could try that tomorrow. However it does look like voltage is getting down there ok.

[Michael Chare]

Do the igniters make a noise exactly 12 secs after you press the rest button?

Maybe wait for the capacitor and see if that solves your problem.

[Dave Baker]

Capacitor ordered off Ebay, posted yesterday, arrived this morning and Houston we have ignition again finally. I am well chuffed. Thanks everyone :)