oil bolier ignites then locks out

[ALSY933]

Hi,

I hope I am accurately describing this post. I have an ages old boiler 'Delheat' don't think they are in business still. The burner is a Selectros and at some time the motor has been changed to a EOGB tipo 60.2.90M and it looks like the con-box has been changed to a Satronic TF701. About 2 weeks ago the boiler wouldn't start because the motor wouldn't spin, I traced this to a faulty capacitor and replaced it with one from Maplins that was 3 microfarad rather than original 4. The boiler worked OK for about a week then would fire up but not stay on, though this was an intermittent fault. I replaced the 3 microfarad cap with an 8 mf one (all are motor starting rated at 440V though they have 4 terminals rather than 2 so I just used 2 terminal and insulated the spares.).

This solved the problem though when then boiler was warming up from cold it would run for quite a few mins (the radiators got to working temp) then switch off and then switch on again almost immediately, the fan would start, the oil would flow, flames would happen then after about 10 secs the control box would lock out. This could be reset after about 30 mins and the boiler would run normally until the CH was satisfied, then when and if the CH operated the boiler by calling for heat, then it would work properly all day, being controlled by the CH. I noticed quite a lot of soot built up, so much so that it continued to burn after the burner locked out; I gave it a good clean, photocell is clean as far as I can see.

Today the boiler has ignited but then locked out after 10 secs as above and I can't clear the fault. I have looped out the thermal cut out and the thermostat to test that part of the system and the same still happens.

I'm not being tight I know the boiler is basically past it but I'm extending the house in the summer and want to wait until then before replacing the system as I shall be moving the boiler location.

Oh and I've tried to get about 3 engineers round to look at it but no-one's interested.

 

[Terrywookfit]

Is the burner wired for a pre purge /does motor run for a few secs before oil is released?

 

[WDIK]

deleted duplication

 

[WDIK]

edit reread post;

Hi,


. I noticed quite a lot of soot built up, so much so that it continued to burn after the burner locked out; I gave it a good clean, photocell is clean as far as I can see.

if you have soot the combustion is off
the head will be fouled and the heat exchanger will be starting to block,
get it cleaned and set up it will only get worse.

the burning on is the soot burning

 

[WDIK]

triplication

 

[oilman]

Get the right size capacitor, otherwise you will have a burnt out motor as well as whatever problem. Look on the oftec website for a technician.

 

[ALSY933]

Thanks for help,

Boiler is set for pre-purge.

As off this morning I managed to ignite boiler using the illuminated lock-out press button on the control box.

I'm having problems finding the correct capacitor - any ideas?

Also, I'm thinking now that the boiler locks out when the spark is removed (what seems to happen is that the fan runs, a spark produced, the oil introduced and ignited, then after a few seconds the spark is shut down) - at this point the system seems to shut down but it appears that the control box closes the system down rather than the flame failing.

Stress though that I don't know the above for sure and don't know how to test.

 

[WDIK]

Thanks for help,

Boiler is set for pre-purge.

no it isnt the control box does this as safety function

As off this morning I managed to ignite boiler using the illuminated lock-out press button on the control box.


I'm having problems finding the correct capacitor - any ideas?
parts centre

Also, I'm thinking now that the boiler locks out when the spark is removed (what seems to happen is that the fan runs, a spark produced, the oil introduced and ignited, then after a few seconds the spark is shut down) - at this point the system seems to shut down but it appears that the control box closes the system down rather than the flame failing.

the spark runs for a predetermined period and stops when no flame is detected within a set time then the control box locks out all functions of the burner are controled by the satronic control box the only control from the boiler is via the temperature control stats and timer

Stress though that I don't know the above for sure and don't know how to test.

there is no test to cure what is a physical defect.
this the boiler is clogged with soot get it cleaned out and get the combustion set up to burn correctly

 

[Terrywookfit]

If burner is set for pre purge check combustion head/ electrodes for smeg!!

Any false light in pre purge will cause burner lock out!

AS previously stated if producing soot attention is needed!!

 

[Terrywookfit]

WDIK wrote.
Boiler is set for pre-purge.

no it isnt the control box does this as safety function


The control box can be wired with or without pre purge depending if an oil solenoid is fitted!!

 

[WDIK]

WDIK wrote.
Boiler is set for pre-purge.

no it isnt the control box does this as safety function


The control box can be wired with or without pre purge depending if an oil solenoid is fitted!!

not what i wrote read the red print

 

[ALSY933]

Everyone

Thanks for your help so far.

What happens is definitely this. The CH switches the boiler, the orange light on the control box comes on, resetting this sets the fan running for about 10 seconds, during which time there are sparks at the electrodes. Then oil is pumped and blue flames appear in the combustion area, this continues for approx 9 seconds at which point the control box switches every thing off and the orange light comes back on. After a couple of minutes the control box emits a faint click and it is possible to repeat the above.

Reading the replies I have cleaned everything and the only other thing I can think of is that the control box can't see the flame. I ran the system with the photocell open circuit (1 wire disconnected) and permanently closed (looped out) neither of these tests made any difference.

I'm obviously not an engineer and am trying to get one to come round, but any suggestions in the interim would be very welcome. To my laypersons eye the flame is very strong and no different to when the boiler is operating well.

 

[oilman]

Blue flame = far too much air or insufficient oil pressure. You first need to check the oil pressure at the pump. Nominally 100psi but may be greater depending on ..............

Next the air should be adjusted so you get a bright yellow flame. However as you have a Selectos burner, these take more adjustment, and you really should get someone who can work properly with oil burners not just someone who paints by numbers.

 

[MANDATE]

I used to have a hit and miss problem and mine is a 'selectos burner'. It seemed ok until the oil level in tank was low then realized the pump had to lift the oil a few feet and could be struggling. A (£10) pressure gauge soon confirmed the problem. 19 lbs sq in when should be 100 psi.
Replaced pump and control box, both ok up to now! that was 1997.

 

[MANDATE]

Just wondering if your oil pump has a solinoid, in which case the coil may be related to your problem.
I tested a relay off a tumble dryer and it seemed to work ok when I switched it on and off every every 4 or 5 secs, but then I left it energised and it failed after about 1 minute and continued to do this. This must have been due to expansion and contraction as the coil heated and cooled. Used to be a similar problem on cars, start when cold but refused when hot.