Omega Owners Forum
Chat Area => General Discussion Area => Topic started by: Field Marshal Dr. Opti on 23 November 2025, 11:32:55
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20 year old HRM Wallstar boiler that runs on oil.
It turns over for about 15 seconds before lock out and then a red light. Try again (repeatedly) and the same thing happens. No ignition. :-\
Plenty of oil in the tank, and you can see it being drawn up the pipe to the pump.
It was working OK a few days ago.
I'm wondering if it is the photo cell as I think it may be the original but could be completely wrong.
Anyone boiler savvy on here?
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Have you tried asking your favourite AI bot? ChatGPT? Grok? etc ???
I believe they're quite clever these days. :y
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Have you tried asking your favourite AI bot? ChatGPT? Grok? etc ???
I believe they're quite clever these days. :y
I asked ;D
This sounds like a classic ignition failure issue with your oil-fired boiler. The 15-second run before lockout is typical for the safety time-out period, where the control box tries to establish a flame. Since it fails to detect a flame, it shuts down to prevent unburnt oil from accumulating, which is a significant hazard.
Given the age of the boiler and the symptoms, here are the most likely causes, ranging from simple to more complex:
🔍 Most Likely Causes of No Ignition
1. Faulty or Fouled Electrodes
The ignition electrodes are responsible for creating the spark that lights the oil spray.
• Symptom: No spark at all, or a weak/intermittent spark.
• Cause: The porcelain insulators can crack, or the electrode tips can become dirty, covered in soot, or incorrectly positioned due to wear. This prevents the high-voltage electricity from creating a strong, consistent spark.
2. Failed Photocell (Cad Cell)
The photocell or Cadmium Sulphide (CdS) cell is the "eye" of the boiler. It detects whether a flame is present.
• Symptom: The burner might spark and even ignite for a second, but the photocell fails to sense the flame, or it's simply failed. Since the control box doesn't register a flame within the 15-second window, it locks out.
• Cause: The cell itself has failed, or more commonly, it's covered in soot and can't "see" the flame even if it ignites. The photocell is a common point of failure for an older boiler.
3. Oil Nozzle Clog or Failure
The nozzle atomizes the oil into a fine mist so it can be easily ignited by the spark.
• Symptom: The burner motor runs, the pump is drawing oil, but the spray pattern is poor or non-existent, preventing a proper flame.
• Cause: The tiny orifice of the nozzle can become clogged with sludge or debris from the oil line, especially after the boiler has been sitting or the fuel filter is due for a change. Given the boiler's age, a worn nozzle is also highly probable. Nozzles should be replaced annually.
4. Air-Lock in the Oil Line
Although you see oil being drawn, there might be a small air bubble (air-lock) trapped in the pump or oil line, particularly if the oil level dropped very low recently or if the system has been opened.
• Symptom: Oil is supplied, but the pump cannot maintain the pressure needed to atomize the fuel properly.
• Fix: An engineer would bleed the pump to remove the air.
5. Failed Oil Burner Control Box
The control box (often a small black or grey box on the burner) manages the entire sequence: pre-purge, spark timing, fuel solenoid, and monitoring the photocell.
• Symptom: The cycle fails, even when all other components are working.
• Cause: Internal electrical failure. This component often requires full replacement.
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
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Have you tried asking your favourite AI bot? ChatGPT? Grok? etc ???
I believe they're quite clever these days. :y
I asked ;D
This sounds like a classic ignition failure issue with your oil-fired boiler. The 15-second run before lockout is typical for the safety time-out period, where the control box tries to establish a flame. Since it fails to detect a flame, it shuts down to prevent unburnt oil from accumulating, which is a significant hazard.
Given the age of the boiler and the symptoms, here are the most likely causes, ranging from simple to more complex:
🔍 Most Likely Causes of No Ignition
1. Faulty or Fouled Electrodes
The ignition electrodes are responsible for creating the spark that lights the oil spray.
• Symptom: No spark at all, or a weak/intermittent spark.
• Cause: The porcelain insulators can crack, or the electrode tips can become dirty, covered in soot, or incorrectly positioned due to wear. This prevents the high-voltage electricity from creating a strong, consistent spark.
2. Failed Photocell (Cad Cell)
The photocell or Cadmium Sulphide (CdS) cell is the "eye" of the boiler. It detects whether a flame is present.
• Symptom: The burner might spark and even ignite for a second, but the photocell fails to sense the flame, or it's simply failed. Since the control box doesn't register a flame within the 15-second window, it locks out.
• Cause: The cell itself has failed, or more commonly, it's covered in soot and can't "see" the flame even if it ignites. The photocell is a common point of failure for an older boiler.
3. Oil Nozzle Clog or Failure
The nozzle atomizes the oil into a fine mist so it can be easily ignited by the spark.
• Symptom: The burner motor runs, the pump is drawing oil, but the spray pattern is poor or non-existent, preventing a proper flame.
• Cause: The tiny orifice of the nozzle can become clogged with sludge or debris from the oil line, especially after the boiler has been sitting or the fuel filter is due for a change. Given the boiler's age, a worn nozzle is also highly probable. Nozzles should be replaced annually.
4. Air-Lock in the Oil Line
Although you see oil being drawn, there might be a small air bubble (air-lock) trapped in the pump or oil line, particularly if the oil level dropped very low recently or if the system has been opened.
• Symptom: Oil is supplied, but the pump cannot maintain the pressure needed to atomize the fuel properly.
• Fix: An engineer would bleed the pump to remove the air.
5. Failed Oil Burner Control Box
The control box (often a small black or grey box on the burner) manages the entire sequence: pre-purge, spark timing, fuel solenoid, and monitoring the photocell.
• Symptom: The cycle fails, even when all other components are working.
• Cause: Internal electrical failure. This component often requires full replacement.
I'm thinking this. You occasionally need to clean with a drop of white spirit so it can 'see clearly'
I've done this but still no go.
I could buy a new one but the whole thing is so old and creaky it may not be worth my trouble.
Can you still buy new oil boilers or have the environmentalists put a stop to this? :-\
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
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Fortunately we have a large open fire to fall back on and more than enough free wood available. :y
Yo can't beat an open fire.
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... I will never buy an EV that runs on PP9s>:D
They don't seem to work very well from what I hear.
::) ::)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... I will never buy an EV that runs on PP9s>:D
They don't seem to work very well from what I hear.
::) ::)
I'd be saving the world twice. Once with a heat pump and again with a milk float. >:D
Even I have my limits. :)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
With his vast tract of land in rural Lincolnshire, i would think that a ground source heat pump would be more fitting. ;)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
Yep...that sounds about right, Lizzie.
I hear they work 'reasonably well' for a few people but poorly for many others.
I'll avoid if at all possible.
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If it's not igniting at all it's not the photocell. More likely the ht transformer, fuel solenoid or pump.
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
Until Mrs Opti decides that you need to save the planet a bit more. >:D
Then you'll be here telling us how fantastic it is, we really don't need to heat our houses to 20 degrees and you didn't realise that 14 degrees can be quite comfortable when you're wearing half a dozen jumpers! ;D
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
Norwegians are hardy folk who wear those big chunky fishermans jumpers so they don't realise how cold their houses are. :)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
Our houses are not insulated to any kind of degree to those in Norway. You need to keep any heat which is generated, not pass it through your roof, windows and walls.
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Our houses are not insulated to any kind of degree to those in Norway. You need to keep any heat which is generated, not pass it through your roof, windows and walls.
I agree 100%, I'd never advocate for one in an older house, but in the new build house Lizzie mentioned, a heat pump, correctly sized and setup should be more than up to the job.
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Our houses are not insulated to any kind of degree to those in Norway. You need to keep any heat which is generated, not pass it through your roof, windows and walls.
I agree 100%, I'd never advocate for one in an older house, but in the new build house Lizzie mentioned, a heat pump, correctly sized and setup should be more than up to the job.
I'd wager your average new build house, especially if built by one of the big companies, isn't insulated enough for a heat pump.
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And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
.. but they build houses properly, have actually invested in their energy infrastructure since the 1960s, have an abundance of renewables and don't put daft green subsidies on their electricity bills, I'm guessing.
Being Scandinavian, they probably supplement it with lots of wood burning, too.
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And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
We burn wood too, Kevin. They grow it in Canada, turn it into pellets and send it by sea and rail to our environmentally friendly power station at Drax.
.. but they build houses properly, have actually invested in their energy infrastructure since the 1960s, have an abundance of renewables and don't put daft green subsidies on their electricity bills, I'm guessing.
Being Scandinavian, they probably supplement it with lots of wood burning, too.
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
Until Mrs Opti decides that you need to save the planet a bit more. >:D
Then you'll be here telling us how fantastic it is, we really don't need to heat our houses to 20 degrees and you didn't realise that 14 degrees can be quite comfortable when you're wearing half a dozen jumpers! ;D
I have no idea what these figures mean. My puny brain only works in Fahrenheit.
Cars set to 70 degrees in old money. :)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
Until Mrs Opti decides that you need to save the planet a bit more. >:D
Then you'll be here telling us how fantastic it is, we really don't need to heat our houses to 68 degrees F and you didn't realise that 52 degrees F can be quite comfortable when you're wearing half a dozen jumpers! ;D
I have no idea what these figures mean. My puny brain only works in Fahrenheit.
Cars set to 70 degrees in old money. :)
Dinosaur! ;D
Anyway I've fixed it for you. :y
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If it's not igniting at all it's not the photocell. More likely the ht transformer, fuel solenoid or pump.
Thanks Kevin. I replaced the pump about 5 years ago. I don't want to replace any 'suspect' parts in the hope I may get lucky. It could cost me a fortune. :)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
And yet 60% of homes in Norway have them, and year ok year they don't all freeze to death...
I think it's far more likely that we in the UK don't have the expertise to size, install and configure them correctly (yet).
Norwegians are hardy folk who wear those big chunky fishermans jumpers so they don't realise how cold their houses are. :)
......and if they are lucky Norwegian men have 22 year old blonde leggy Norwegian girls to keep them warm during long winter nights. :)
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I think our Lord should get rid of that dirty old boiler, replace it with an Air Source Heat Pump and save the planet! :)
Not while I still have breath in my body..... >:D
They don't seem to work very well from what I hear.
I think you may be right Opti.
One of my friends very recently moved into a brand new house which has been fitted with one of these new fangled heat pumps. Over the last week it has become very cold down here, but she tells me the heating will only get to a certain level and no more, with her bedrooms remaining quite cold! Another friend of mine is a master builder, and is very well qualified in the plumbing, and electrical, fields. He says that the heat pumps have a limit on how much heat they actually push out, which is no where near as high as it is with an gas central heating system. :o :o :o
What the hell is going on I think?!! Why are heat pumps being so enthusiastically promoted if they have limits for houses in our climate?! ::) ::) :P :P
The biggest issue with heat pumps is they are complicated to setup and get working well......sadly the fitters are not up to the task all to often.
You also need good insulation, suitable sized heat emitters (radiators, under floor heating etc, to run at a lower flow temperature), and to run them 24/7 (with the hot water heating at low cost hours.
Do this and they are excellent......but you have to get over the first problem first
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If it's not igniting at all it's not the photocell. More likely the ht transformer, fuel solenoid or pump.
Thanks Kevin. I replaced the pump about 5 years ago. I don't want to replace any 'suspect' parts in the hope I may get lucky. It could cost me a fortune. :)
Pretty sure you could pull the photocell and test it with a torch and a multimeter. :y
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If it's not igniting at all it's not the photocell. More likely the ht transformer, fuel solenoid or pump.
Thanks Kevin. I replaced the pump about 5 years ago. I don't want to replace any 'suspect' parts in the hope I may get lucky. It could cost me a fortune. :)
Pretty sure you could pull the photocell and test it with a torch and a multimeter. :y
Didn't even occur to me. Would this work?
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have you checked the nozzle for any signs of oil? if dry then it sounds like a fuel issue ( pump or solenoid)
pump - you can check it is reaching pressure with a cheap ~10 quid pressure gauge
solenoid - check the resistance - open circuit - suspect the solenoid
typically there are diagostic flow charts on line for whichever burner you have so have a look for that and follow it - oil burners are pretty basic tech so not hard to diagnose tbh
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Didn't even occur to me. Would this work?
YouTube seems to think so.
https://youtu.be/uBZ7NIEEvck?si=RsJt0OTwc-akTvJI (https://youtu.be/uBZ7NIEEvck?si=RsJt0OTwc-akTvJI)
It might be useful to know what the values should be. But given the age of boiler, I suspect it won't be that precise.
;D
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have you checked the nozzle for any signs of oil? if dry then it sounds like a fuel issue ( pump or solenoid)
pump - you can check it is reaching pressure with a cheap ~10 quid pressure gauge
solenoid - check the resistance - open circuit - suspect the solenoid
typically there are diagostic flow charts on line for whichever burner you have so have a look for that and follow it - oil burners are pretty basic tech so not hard to diagnose tbh
I've pulled the unit out and cleared the 'back box' (no idea if that is what it is called) of soot. Removed the nozzle which appears black and blocked and have left it overnight in white spirit. I'm hoping it is this that is stopping ignition if no fuel if getting through.
I will also adjust the igniter tips that should be set 3mm apart, and level with the top of the nozzle.
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Didn't even occur to me. Would this work?
YouTube seems to think so.
https://youtu.be/uBZ7NIEEvck?si=RsJt0OTwc-akTvJI (https://youtu.be/uBZ7NIEEvck?si=RsJt0OTwc-akTvJI)
It might be useful to know what the values should be. But given the age of boiler, I suspect it won't be that precise.
;D
Thanks Jimmy. :y
The photocell is easy to remove so I'll give it a try.
My photocell is the same as the second on in your video, only longer. Mine appears to be 80mm, the one in the video looks 40mm.
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OK....so following the advice of Jimmy the Photocell seems to work as it should regarding light and dark.
I've turned the burner around (so it is facing outward) and I can now see there is no spark at the igniters. So some progress. ::)
AI for no spark throws up burner control box....possible HT lead failure, ignition transformer fault.
Take your pick. ;)
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touch those bits with a licked finger. You will soon know by the bit that kills you which is faulty ;D
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touch those bits with a licked finger. You will soon know by the bit that kills you which is faulty ;D
For a moment there I thought you were talking about wet fanny. >:D
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touch those bits with a licked finger. You will soon know by the bit that kills you which is faulty ;D
For a moment there I thought you were talking about wet fanny. >:D
If that's the way you want to moisten your finger, that's your prerogative. ;)
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touch those bits with a licked finger. You will soon know by the bit that kills you which is faulty ;D
For a moment there I thought you were talking about wet fanny. >:D
If that's the way you want to moisten your finger, that's your prerogative. ;)
Yuk. The smell of burnt fish.
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I've turned the burner around (so it is facing outward)...
:o :o :o Good job there was no spark or you'd have had an industrial sized flame thrower to deal with.
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I'm just waiting to see the headlines.....
House Explodes In Lincolnsausageshire!
:o ;D
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I'm just waiting to see the headlines.....
House Explodes In Lincolnsausageshire!
:o ;D
At least the orangery won't go up. :)
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I didn't stand in front of it.... ::)
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Anyway, I'm a bit like Niki Lauda, who according to James Hunt was better looking after the fire than before. >:D
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Managed to get the old girl going again. :y
In the end I took a chance on a used Wallstar 12/14 from Ebay, of 1998 vintage.
Changed the nozzle for a new than cleaned the photocell with white spirit and she roared into life.
£84 for the burner, £9 for a new nozzle, and £7 for Royal Mail P&P from some God forsaken part of the UK.
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Solid result!
With barely over £100 spent, you should have plenty of spare dosh to shower Mrs Opti with gifts this time next week! :-*
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Solid result!
With barely over £100 spent, you should have plenty of spare dosh to shower Mrs Opti with gifts this time next week! :-*
....and I have spare parts from the original unit, some of which may work if anything goes tits up.
Thing is, I was looking at a complete new system for about £10,000. I'm not from the north, but I still hate spending money. >:D
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Sounds like you've sorted it then, just in time for the cold snap they are promising.
Superb :y
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Sounds like you've sorted it then, just in time for the cold snap they are promising.
Superb :y
I know it would be far more easy to buy a new system, or pay for some 'hairy-arsed' engineer £100P/H to fix it, but I really like to fix things myself, if I can.
I can remember draining the septic tank with buckets (I later bought a pump) to find the blockage to the soakaway. That was a proper shit job. :-\ :)
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Sadly, as with cars these days, your £100 p/h more often than not buys you a component changer with a similar level of access to Google as you have at home :-\