Sterling 40 ST 108 with inetrmittent lockout

[grill]

Hi guys,

Was recently called out to a Sterling oil burner (cant remeber model name) which locks out intermittently.

The burner can run away merryily for hours, come on and off with the thermostat but then sometimes just locks out. Hit the reset button and away it goes again for another while.

He said the burner has run now for 3 days with no problem but locked out again tonight.

I thought it might be the control box and stuck a new one in to test. Still does it though. Someone else has suggested that it might be the motor capacitor that causing the problem. Where is this on this model an dhow do i test if its the problem. Checked the manual and it isnt instantly obvious.

Any thoughts would be welcome.

Grill

 

[wilhelm]

look at the ebi transformer. if its distorted?

but hey, do combustion checks and oil press check.

could be capacitor. i test capacitors by grabbing fan and turning on, and feel the kick....

rock on tommy ..........

 

[grill]

Combsution checks and oil pressure are all fine. As i said it can run fine for days and then do it again.

What exactly do you mean by the ebi transformer being distorted and getting a kick out of the fan??????

Grill

 

[wilhelm]

well , grill , we have a problem. anyway change the pump.


the ebi will have a bump on the upper surface if it is f rekked.

the fan scenario....... take motor out, grab fan, turn on. and feel the "kick" youll soon get to know the difference. trust me . it wont take your hand off ..................

 

[oilman]

This is likely to be the control box. I suggest you ge a capacitance meter for the capacitors. You need to disconnect one lead when measuring.

 

[grill]

Hi oilman,

I have already stuck in a new control box and it is still doing it!!

Where would i get a capcitance meter and how do i use it??

Excuse my ignorance

grill

 

[oilman]

Mmm, I should have read your post.

Lets have some information.

When does it lockout? Hot? cold? first of the day? etc.

Use google for meter, has your multimeter got a capacitance range?

The capacitor is mounted on the motor casing.

 

[grill]

Usually when you turn it on for the first kick of the day.Have checked the clock and everything is fine with this. Everything else is going fine. Can also happen randomly though, hot or cold.

The only reason i mentioned the capacitor is that my mate has the exact same burner and was doing the exact same thing. He changed the control box, no joy, checked everything. Spoke to a guy who took a look at it and he said the capcitor was only pulling 2V (?) but it should be about 4.

Checked a riello manual and it states a capacitance of 4.5 uF so i assume this is the came reading.

Think my meter had a capcitance range so can use that.

Anyway he changed the capcitor and its tickety boo.

Does all that make sense??
How do i check with my multimeter??

Cheers for your help

Sean

 

[oilman]

2V? Capacitance is measured in Farads, not Volts, hence uF.

Take the cover off the capacitor terminals. If you can't find them look up "motor run capacitor". Disconnect one lead from a terminal and connect the meter set to uF across the terminals. It should read what it says on the tin, and you can afford a 20% drop. Any more than this it needs replacing.

If it's a cold start problem, it's probably the capacitor because everything will be stiff when it's cold, except if it's an oil problem when it gets stiff when hot.

If you need more details, look up "measuring capacitors".

 

[grill]

Cheers for that oilman, you have been a great help. Ill check the capacitor tonight and if no good stick in a new one and away we go.

Are capacitors burner specific or stock items??

As an aside i was reading a post last about a Potterton oil burner giving problems and someone in there stated that it is not a legal requirement yet to be Oftec registered to work on oil burners!! Is this true and if so why did i fork out that money to become registered!!!!

Thanks again mate. Im sure ill have to bend your ear again!!!!

Grill

 

[oilman]

....... why did i fork out that money to become registered!!!!

Because, like the rest of us, you feel insecure, and having a bit of paper makes you feel less so. You can also say to people who think you are boiler repair man just because you have a piece of paper, that it's like most other pieces of paper and means effall.

 

[cozzmic]

What about the drive shaft dog slipping?

 

[grill]

The motor isnt starting so it wouldnt matter if the drive coupling is slipping or not.

Will stick in a new capacitor and let you know.

Oilman, so basically anyone can work at an oil burner legally?? I thought you needed to be Oftec registered if you were going to break the oil line??

Oh well better to be safe than sorry

Grill

 

[oilman]

Don't know where you got your info, but anybody can do anything, it's just that if you install or commission you have to get building control involved.

The world thinks because you have a piece of paper you are ok, and if yo haven't you might not be.

 

[grill]

Im just basically coming from the point of view that im Corgi registered so legally i can break and test a gas line.

Thought this was the same thing for oil and Oftec!!!!!

Thanks again for your help mate.

Grill