Oil fired boiler. What do you think the problem is.

[Michael Chare]

I have an oil fired boiler, which when switched on will run normally for up to 3 minutes. It then stops, after a few seconds it starts to run again, the solenoid on the oil pump does not open, so the boiler does not light but locks out. The process can be repeated by pressing the reset button

The photocell is good and I have tried a replacement. The resistance of the solenoid is 2100 ohns or so and is thus within spec.

The boiler has a facility to monitor the oil pressure just before it goes into the burner jet. When the boiler is running normally the oil pressure is static at slightly over 100 psi. The jet is new.

The oil level in the tank maybe a few inches below the level of the burner pump, but was 4 inches lower last year before I filled it up.

The Control box is a Honeywell Satronic DKO 972-N

What do you think the fault is? Which component would you replace.

[Graeme]

In message , Michael Chare writes

Does this fault occur every time, or is it random/occasional?

[Brian Gaff]

The question is, why does it stop. The reason why the solenoid is not operated is to stop repeated attempts at a start which obviously shows an issue with the burner or oil etc, I'd imagine. a reset does just that resets the solenoid time to first start.

I unfortunately have never fiddled with oil burners but the problem has to be that the mixture it gets will not burn. Could there be water or some other pollutant in the oil? Is there an airflow issue? Brian

[Michael Chare]

Every Time

[Dave Liquorice]

Fuel starvation?

Filters cleaned and/or paper elements replaced? Possibly cack in the pipe work that drifts up with the flow to a constriction (fire valve?) when the boiler is running then settles away when it's not.

[Adam White]

[Michael Chare]

Really just by chance I watched a Utube video, which said that one boiler problem was that the coil on the oil pump can go open circuit when it warms up after being on for a few minutes. So when the boiler stopped I removed the coil as quickly as possible and it was open circuit. A few minutes later it as back to 2.2k ohms. Managed to cancel order for new control box and order new coil.

Yesterday I rang Worcester Bosch, the technical people told me that they were not allowed to speak to me after I said I was a household rather than an engineer. I did describe the fault and they did not mention that the above was a possibility.