Worcester Combi not firing in morning

[WHPES]

Got a problem with a Worcester combi not firing in the morning from cold.

Boiler approx 14 years old.

Pressing the reset button once only gets the boiler to fire OK.

The fault is intermittent and happens about once per week.

The fault is not connected with frosty weather.

The tank had been contaminated with water and there was dross in the oil line. Flushed line and emptied water out.

Changed pump and solenoid coil, made little difference.

Any suggestions?

 

[Rob Sale]

Have you tested the resistance on the Limit stats? if they are greater than 1 ohms they have a short circuit which could do this.
check aps aswell and thermistors.
clean venturi

Does it have a programmable room stat? i'd check the connections on that.

but hey i am not an oily engineer.

 

[dontknowitall]

Capacitor? Losing charge/whatever it is after a cold spell?

 

[Plumb Ugly]

Is it a gravity or suction oil line?

 

[SimonG]

I'd try a new capacitor.

But I did have one a couple of years ago, intermittent lockout on a morning and it was the transformer.

 

[Roger Welton]

Also had a dodgy satronic box cause bizarre intermittent lock outs.

 

[Bunker]

Is it a balanced flue? leaking gasses?

 

[Billy Bob Bob]

aps????? on a oil boiler

 

[Plumb Ugly]

Could be a micro leak on the oil line allowing air to build up in the line whilst the boiler is off over night then clearing after the first fire until the next extended off period

 

[Best]

First I would check the motor starts on the split second every time, (give it loads of starts to test, with your ear near the burner) - any slight hesitancy & I would think capacitor.
Normally Control box does that, once in a while lockout, but photocells can do weird things.
As has been suggested, check the transformer is making a strong & constant spark.

 

[lame plumber]

aps????? on a oil boiler

gonna have to make you an honary oily, best change your monicker if your moderating this sub forum omho

 

[Billy Bob Bob]

gonna have to make you an honary oily, best change your monicker if your moderating this sub forum omho

oily gas man? looking into oftec and training in the next few months lots of farms near me and the resident oil mans retiring

 

[SimonG]

oily gas man? looking into oftec and training in the next few months lots of farms near me and the resident oil mans retiring

Well if it's for farmers you'll have to be gasoil man

 

[lame plumber]

farmers dont get the likes of us to service their boilers, its diy for them

 

[Plumb Ugly]

If its for farmers you'll have to be dirt cheap oil man! Lol

 

[WHPES]

The line is under pressure (tank higher than boiler).

Will try control box and photocell first and report back.

The burner is going to lockout so nothing to do with stats.

 

[Plumb Ugly]

Over airing could be a possibilty but yeah I'd also try a new photo cell

 

[kimbo]

Could be overaired but you would have already checked the flue gases, I would check the transformer, the EB1,s give the same symptoms, sometimes you can see the bulge in the casing when they are statrting to go.

 

[WHPES]

OK I'll come armed with a control unit, photocell and EB1. If that doesn't sort it I'm really scratching my head!

 

[Roger Welton]

Could be overaired but you would have already checked the flue gases, I would check the transformer, the EB1,s give the same symptoms, sometimes you can see the bulge in the casing when they are statrting to go.

And they stink!

 

[Bunker]

My experience is if the EB1 goes, change the control box aswell, its often the box causing the damage.