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Hi all,


I have a Wallstar Oil Boiler 12/15.

A few years ago, it developed a problem where it would fail and it required a manual reset on the boiler controller outside.

I didn't know much about oil boilers back then.

I have had a number of 'heating engineers' and so-called specialists to it but so far none have cured the problem.

I decided to figure out how these things work for myself to give me a greater understanding of what is going wrong.

So, this is what happens.

When there is demand for heat, the boiler from cold (in a none failed condition) fires up without the slightest problem.

It runs to get the water hot, shuts off, starts again as water cools etc... normal running.

Then, for no apparent reason, say after 30 mins or 1-hour etc, it will fail to ignite. This triggers the fail and requires a reset on the controller.

Sometimes the reset will work and the boiler will fire up and continue, sometimes it will just keep failing.

If I leave it to cool down for a few hours, it will generally fire up as normal (after clearing the fail with the reset).

It seems that when the boiler is very cold, there is no problem. If it is also very hot, it doesn't seem to be a problem, but in-between is where it fails.

The engineers etc have changed the nozzle, plastic pipe, solenoid, controller and filters and the problem persists.

Now then, things I have checked.

When starting, the pump runs (pulsing of the oil can be seen in the clear pipe). It does its 10-15 second purge then the solenoid clicks and the oil flows, boiler lights.

All good.

When it fails, it NEVER fails when running, only on re-starting during the normal heating cycle.

It goes through the normal procedure as above, solenoid clicks open, oil is seen to flow and then within about 3 seconds it shuts off with the fault.

Now, as I can see the oil moving, it isn't the solenoid, it’s not air as I can see the oil in the line, it’s not a blockage as again I can see the oil moving in the line.

It seems to be the igniter.

I have had it apart, cleaned the electrodes, checked the gap 3mm+-0.5mm and level with the top of the nozzle.

It's not the flame detector because when it fires up, you can hear it ignite and it doesn't get that far.

Does anyone have any experience with this same fault and how was it cured?

Could it be the transformer (that creates the spark), the leads to the electrodes or the electrodes themselves.

Puzzling as it only fails when the boiler has been running. The temperature in the burner cabinet is always quite cool, but the fault is definitely heat related!

This must be a known problem, on my street 12 houses, we all have the same boiler and 7 of them have the exact same problem.

Surely someone must know what the problem is.

Oh, the boiler is about 12 years old.

Thanks.

Martin
 

Best

Esteemed
Plumber
Just get a genuine oil service person who has experience in oil burners and some fault diagnosis skills.
That fault as you describe can be narrowed down immediately to a likely cause.
Although tbh, I can think of 3 parts that can cause failure on the timing you mention.
Note that when the system is up to full heat, the oil burner will run less and some parts will be less likely to fail due to heat up causes.

Also, - Just because a part works properly a few times does not mean it is not failing intermittently.
 
Thanks for your reply.

What 3 parts do you think please?

Out of all of us on the street with the same problem we have been through many an engineer.

Now 3 of us have had remote resets fitted so we can re-set the boilers without going outside because no one seems to be able to do anything.

These boilers are not exactly complex which is why it is so annoying that the fault cannot be found.

It is definitely an intermittent fault.

I have 3 ideas at the moment.

1. A crack in the porcelain insulators on the electrodes which is allowing tracking of the ignition spark when it is hot.

2. The short rubber coated HT leads from the transformer to the electrodes. Maybe breaking down with heat.

3. The transformer itself.

As the transformer is on the outside case of the burner, it doesn't get hot, where as the other two are inside the burner itself and subject to heat.

What do you think?

Thanks

Martin
 

Best

Esteemed
Plumber
Electrodes and leads are usually easy to visually rule out.
I have only your description to go by and frankly your service people should have solved it.
Seems strange that 7 out of 12 have the same problem.
I really cannot give advice on open forum of how to tamper with an oil boiler, although I am tempted.
@SimonG is also an oil guy on here, but I think he will say same.
If the fault is so frequent, why has all the service people not replaced a probable faulty part?
 
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Ebi transformer.
Danfoss say they don't have intermittent faults but I've had a few that have started playing up.
I'd change that if the leads and electrodes look ok.
 
Hi, we have a Wallstar 15/20 boiler which has intermittent lockout.

Having had heating engineer to it numerous times and have had firevalve/NRV, clear hose, ebi transformer replaced it ran all through the summer using only for heating water.

Boiler now being used for HW and CH it’s on for longer and has intermittent lockout.
I’ve replaced photocell and solenoid myself and still no joy.

The clear hose has a air bubble which I ceased to a decent size but seems to get to max size then stays at that size with oil either side of bubble.

heating engineer believes it’s this air bubble that’s causing issue, yet when air is removed from clear hose in the evening the boiler locked out the next day so I’m not convinced it is the air that’s issue. Was suggested by him that a tiger loop would solve problem, again im not convinced.

I’ve no problems with spending money on the boiler to get it fixed but don’t want to waste money on replacing parts or adding parts if it ain’t going to fix it.

after reading several over forums I decided to try the capacitor. Found a local company and got new one for £6, wasn’t sure how to remove the existing one so I’ve temporarily cable tied the new one to the existing on for time being. The old capacitor had brown residue around the base of the terminals.

I hope that this resolved my issue...

Anyone got any suggestions on removing capacitor and also on how they have sorted boiler out?
 
Theres a reply to this but I cant see it again? I know this thread is old but would be keen to know if the OP has a result. From what I've read this sounds as if it's an ignition problem which is what you guys have suggested above.
 
Hi, we have a Wallstar 15/20 boiler which has intermittent lockout.

Having had heating engineer to it numerous times and have had firevalve/NRV, clear hose, ebi transformer replaced it ran all through the summer using only for heating water.

Boiler now being used for HW and CH it’s on for longer and has intermittent lockout.
I’ve replaced photocell and solenoid myself and still no joy.

The clear hose has a air bubble which I ceased to a decent size but seems to get to max size then stays at that size with oil either side of bubble.

heating engineer believes it’s this air bubble that’s causing issue, yet when air is removed from clear hose in the evening the boiler locked out the next day so I’m not convinced it is the air that’s issue. Was suggested by him that a tiger loop would solve problem, again im not convinced.

I’ve no problems with spending money on the boiler to get it fixed but don’t want to waste money on replacing parts or adding parts if it ain’t going to fix it.

after reading several over forums I decided to try the capacitor. Found a local company and got new one for £6, wasn’t sure how to remove the existing one so I’ve temporarily cable tied the new one to the existing on for time being. The old capacitor had brown residue around the base of the terminals.

I hope that this resolved my issue...

Anyone got any suggestions on removing capacitor and also on how they have sorted boiler out?
Hi. Your comment has only just become visible to me!
If you have a multimetre capable of reading capacitance then you could test old capacitor to see what its value it has, I suspect however if you're saying its showing sign of dielectric leakage then it might very well be the culprit, although I'm not saying for sure it is or that there isn't other faults, time will tell.
With regards to the air bubble are you sure you're not drawing air in? These Wallstar boilers are obviously designed to be mounted on an external wall and able to draw oil up a maximum of 2 to 2.5 metres if I remember correctly. This means the oil will be sucked up and under negative pressure for part of the supply line, also if this negative pressure was too low gases can separate in the oil causing these problems. However if this has been fine for sometime before the problem then I doubt the install is wrong.
A tigerloop will lift, deaerate and preheat the fuel but many of these boilers work fine without one providing installed correctly and don't exceed suction capacity of the pump, so unless you have a constant air ingress problem then you shouldn't need one.
If it was just the capacitor then I expect you to not have experienced another lockout in the time between your comment and my reply now.
 

SimonG

Plumber
Advent Win
The wallstars always have an air bubble in the clear oil hose. Never seen one without it.

Capacitor would make sense.
 
Hi. Your comment has only just become visible to me!
If you have a multimetre capable of reading capacitance then you could test old capacitor to see what its value it has, I suspect however if you're saying its showing sign of dielectric leakage then it might very well be the culprit, although I'm not saying for sure it is or that there isn't other faults, time will tell.
With regards to the air bubble are you sure you're not drawing air in? These Wallstar boilers are obviously designed to be mounted on an external wall and able to draw oil up a maximum of 2 to 2.5 metres if I remember correctly. This means the oil will be sucked up and under negative pressure for part of the supply line, also if this negative pressure was too low gases can separate in the oil causing these problems. However if this has been fine for sometime before the problem then I doubt the install is wrong.
A tigerloop will lift, deaerate and preheat the fuel but many of these boilers work fine without one providing installed correctly and don't exceed suction capacity of the pump, so unless you have a constant air ingress problem then you shouldn't need one.
If it was just the capacitor then I expect you to not have experienced another lockout in the time between your comment and my reply now.
[//sjb060685
Hi SJB060685 thanks for your reply, took awhile to show on here as it said had to be approved.

I forgot to add to my post that we had a new oil tank installed back in 2017, the oil tank was moved to new position. We had this issue prior to the new oil tank.

Since fitting new capacitor the boiler has worked without issue but as it is intermittent the boiler sometimes goes a week without lockout so not counting my chickens at the moment.

The pump on the boiler is less than 2 meters above the outlet on oil tank.
I did read on another forum about gases causing the bubble.
I’m not sure if our heating engineer has checked pump pressure.
Heating engineer has checked all of the oil line connections.

Any idea how the old capacitor is removed?
 

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