Oil burner occasionally not firing

shunney

Hi,

We have a Grant euroflame Kerosene boiler that sometimes won't start up, this started out at random, but now happens most mornings.

I'm having to press the reset button that's behind a black screw cap next to a dial, if i'm correct this is the thermostat ?

Once the button is pressed it will work away fine until the next morning. It's also burning a lot more oil than it used to, does this mean the thermostat is at fault ?

Any help appreciated, thanks

TPM

First step is to get it properly serviced.

The reset button you are pressing is the boiler over temperature safety, it trips when the boiler exceeds safe working temperature you should not keep resetting this as it could present safety issues and/or damage the boiler.

You could turn the boiler temperature stat down a bit to see if this helps, but you still need to get the boiler serviced which will also help your oil consumption.

jimf

have you noticed your rads/water getting excessively hot recently even though you have the control stat set to the usual setting usually this tripping of the high limit stat is a circulation problem ie faulty cirl pump low water pressure the fact you have noticed excessive oil usage it might be a faulty control stat allowing your boiler to run over normal operating temp then the safety feature of your boiler ie high limit stats kicks in and does what it says on the tin

shunney

Good that I asked, I've been pressing that for a few weeks now...

That makes sense then, because in a morning it's only set to come on for 1.5 hours and in the evening it's on for 5 hours in this weather, so excessive burning for 5 hours can't be good. It seems maybe the thermostat isn't doing it's job then.

I've not noticed the water or rads being too hot, but after noticing the oil burning faster, I realised that the burner sounds like it's coming on far too much.

Could the thermostat inside possibly cause this ? we have an old analogue stat inside and it's definitely not reading the temps correctly. I have a thermometer in that room and it can be 20c in the room with the stat on 15c and the boiler will still be burning away. I'm not sure how it all works to be honest, just trying to make sense of it all.

Thanks guys

jimf

faulty room stats/ timer would not be causing your high limit stat to be tripping these would only be controlling the heat demand to the boiler

shunney

It all confuses me, i'm just trying to think logically, but not quite grasping it.

I'm thinking that if the stat inside is at 15c then shouldn't the boiler only come on if the temp in the room drops to 15c ?

and if there's a stat inside and one on the boiler, which one is controlling the temps

jimf

with the boiler running turn your room stat to the lowest setting and see if the boiler cuts out if it doesnt then you have 2 problems the stat at the boiler is governed by the water temp in the boiler only

TPM

The stat inside is to control the room temperature, like you say if it is set to 15 and the temperature drops below 15 it will turn on the heating system, both the boiler and the circulating pump.
The stat on the boiler controls the temperature the boiler heat to once it reaches the set temp it turns of the burner but not the circulating pump.

So if the room stat is set to 15 and the boiler stat is set to 65
the room temperature drops to 14
this turns on the boiler(burner) and circulating pump
The burner heats the water and the circulating pump circulates it through the rads
when the boiler reaches 65 the stat turns off the burner but the circulating pump keeps circulating the water
when the boiler drops below 65(there is a few degrees differential) the burner fires up again
this keeps repeating untill the temperature in the room reaches 15 and turns off the boiler and the pump.

shunney

I see I think I got it now, thanks guys.

So the indoor stat is definitely not reading the temps correctly. The lowest setting is 15c, if I turn it more then it clicks off, which also then switches the boiler off, but the temperature side of it doesn't switch it off, because like I said my thermometer is reading 20c and above and it still burns away.

The stat on the boiler only has a line on the dial for reference and no actual numbers, so no idea what temp it's at, but i'll turn it right down for now, at the moment it's about a quarter way up.

If i'm now correct in thinking, the boiler will just keep burning until it reaches the temp of the boiler stat, switching off and re-firing on a loop until it reaches the temp of the indoor stat, which it can't because the indoor stats not sensing the temps properly.

So basically it will just keep burning on and off via the boiler stat until the program timer cuts it off.... No wonder it's tripping the switch then, after 5 hours it's probably ready to explode !

Billy Bunting

I may of missed it but do you have a secondary heat source ?

shunney

Billy Bunting wrote: »

I may of missed it but do you have a secondary heat source ?

No mate, other than an open fire (no back boiler) and the immersion switch (which is never used), just the main boiler in question.