Oil Boiler Cutting Out

[slog51]

Hi all, having some problems with my oil fired boiler. I realise there are a million and one of these threads already but can't find anything with the same symptoms so hope someone can help...

Boiler is a Grant Vortex Pro (external) with Riello RDB1 burner. The boiler fires ok when the heating is switched on, but only stays on for 30 minutes to an hour before cutting out. Lock-out / reset button does not switch on. Heating and hot water etc. circulate fine whilst the boiler is working.

Oil level is fine, and the tigerloop appears to be functioning. I've checked the solenoid and resistance seems to be in the correct range.

Any ideas of where else to check? My next thoughts were the thermostats but i'm not sure of the best way to verify that these are working correctly.

 

[oilboffin]

No the lock out says there's a prob with burner chech the pump pressure first and check the flow of
oil.if ok check the voltage on the White wire from the motor to the control box it should be 50volts,
if not motors goosed even though it runs.Bob

 

[Terrywookfit]

No the lock out says there's a prob with burner chech the pump pressure first and check the flow of
oil.if ok check the voltage on the White wire from the motor to the control box it should be 50volts,
if not motors goosed even though it runs.Bob

Rather a sweeping diagnosis Bob!!

 

[oilboffin]

Not really mate had a job motor gave30volts on White wire then could only get 80psi on pump then found that after 15mins the oil was droping so had to blow out pipe and fit new filter and before anyone says anything there wasn't a 2 bar wash pressure on the riello pump all in all a pig of a job
so you have to look at a big picture.Bob

 

[slog51]

Thanks for the responses. I can't see a wiring diagram anywhere in the manual but i see the motor connector has 3 wires - black, white and blue. Do i measure between white and black? Not a whizz when it comes to electronics i'm afraid and it's been a while since i dusted of my DMM. For what it's worth, I think the motor is running ok - i.e. i can hear it, and it switches off when i remove the connector from the control box.

What's the best way to check the pump pressure?

 

[Terrywookfit]

Yes black and white wires.

Would you believe a pressure gauge!?

 

[slog51]

Of course

Gauge into the gauge connector would make perfect sense. Sure i have one somewhere...

Seems to be 64V across the wires.

 

[oilboffin]

Or White and earth

 

[oilboffin]

Oh oh Terry ha ha nice.Bob

 

[oilboffin]

A lot of people don't believe you when you say motors gone when it's still running but the 50 volts is to drive the control box.Bob

 

[oilhead]

Sounds more like an external controls problem if burner and pump are stopping.

 

[oilboffin]

When you press the reset button does the burner run or just hum.Bob

 

[slog51]

Just hums away. The reset button never seems to light up despite the burner not working.

Control box was my other idea. Waiting to get a pressure gauge from a friend this evening so I can check the pump.

 

[Burnerman]

If the motor is just humming rather than spinning, either its goosed or maybe the start capacitor has called it a day?
John

 

[Malc]

When you say the lock out does not light up why do you think the boiler is at fault? Are you sure that the CH pump is running and running at the right speed? I've had what might be a similar problem. Boiler wasn't running, power light was on, lockout light off, no response to pressing reset button. What had happened was boiler had fired when I'd not been looking. CH pump was seized so boiler just heated water inside boiler then cut out due to the thermostat like it should do. Since boiler was well insulated it took about 20min before it cooled enough to restart for a couple of minutes. Solution was to change the CH pump.

I would suggest turning down the boiler thermostat then letting it run. When it stops working after 30 mins try turning up the boiler thermostat. If it then fires and runs for a minute or 2 then boiler is working fine it is you CH pump that is getting tired, or something else stopping the pump.