Grant Oil Boiler, Riello RDB1 burner, intermittent lockout

[Onoff]

The value will be written on the side in uF or MFD. Around 3.5 or 4uF I think it'll be. They're plastic so if duff probably won't be obvious if blown as in split or swollen.

You will need a capacitance meter to check it. Shop around and you'll get a cheap multimeter for around a tenner that'll do it.

DT9205A AC DC Voltmeter Ammeter Capacitance Tester Meter LCD Digital Multimeter | eBay

DC current: 2m-20m-200m-20A±1.0%. Resistance: 200-2K-20K-200K-2M-20M-200M±1.0%. Capacity: 20n-200n-2u-20u-200uF±4.0%. 3-digit LCD, maximum display value 1999. Alternating current: 2m-20m-200m-20A±1.5%.

www.ebay.co.uk

Capacitor something like this:

Riello MECTRON 40 4uF Capacitor 20087025 3005798 - Polish made - NEW - free post | eBay

Is your burner buzzing and not starting?. or locking out in the mornings?. or is it sounding slow to start?. These are made in the biggest capacitor factory on Poland - not the Chinese types.

www.ebay.co.uk

Worst case you might have to add some crimps on to the new wires or just join new wires to old with some inline crimps.

 

[dobbslc]

Have you bleed the pump? You,probably have but you didn't mention it in the first post, that can take quite a long time to get the air out. Theres a thermal cut out on the flow pipe on mine, I had air in the system that meant it cut out a few times, worth checking.
You could try rigging up a bottle of fuel to eliminate a problem with the supply side of things, like this.

 

[angellonewolf]

i dont know any thing about boilers stuff

but capactors need to have the right uf value but the voltage can be higher but not lower

im sure some one will comfirm this

 

[Onoff]

Check the fire valve too, they can get mucky and stick / clog as they can be the first port of call for the oil coming from the tank. Similarly the capillary tube that goes to it (the fire valve) for crush damage.

Thinking back...there's a little plastic coupling between pump and motor that can break. Also a tiny metal key on the pump.

Tbh my set up is now like Trigger's Broom.

 

[reb78]

Check the fire valve too, they can get mucky and stick / clog as they can be the first port of call for the oil coming from the tank. Similarly the capillary tube that goes to it (the fire valve) for crush damage.

Thinking back...there's a little plastic coupling between pump and motor that can break. Also a tiny metal key on the pump.

Tbh my set up is now like Trigger's Broom.

Re the fire valve - done. When we blew the pipe through we disconnected prior to the valve and blew the line through. Then blew back from the pump flexi through the fire valve. All clear. Good flow.

Key and coupling are on my mind. But would it run fine for a period and then stop if they were to blame?

 

[Onoff]

Part 24 is the plastic coupling:

To do the bearings in the motor I had to split it apart.

Pretty sure the key is under the pump cover plate accessed by the 4 screws.

If you take the pump off the motor you might see some rust in there from the bearing. You can clean that out and give a squirt of some WD etc. It won't get to the bearing the other end of the motor though.

What are your symptoms. Mine would buzz where the motor was stuck, try to fire up, then lock out.

 

[reb78]

Ive never been there when it locks out. So the most I can say is it runs and may run again and again fine and either locks out at the end/midway of a burn or at the start of the next one. Its weird as its run over 24h before locking out this evening.

 

[dobbslc]

Similar symptoms to mine when the photo cell failed, it's an easy test with a multimeter. I could be teaching you to suck eggs here but worth a check

 

[daedalusminos]

Yes, it will fire up fine when you are stood by it.

It could easily be an intermittent fault with the igniter (or the controller - or anything). I'd swap igniter for a known good one.

 

[Misterg]

Same as above. How do I test it?

Just change it, or you could use the capacitance range on your multimeter (if you/it has one).

This is the one that was in ours (Riello burner in a Firebird boiler - 4.5uF). I believe that there may be different values, so check the uF value against what you have first.

Riello Burner Capacitor, 4.5uF, 3002837, 20071576 | Buy at H.P.W.

Riello Burner Capacitor, 4.5uF, 3002837, 20071576 available to buy online, with fast tracked delivery. Heating Parts Warehouse the specialists in plumbing and heating parts and spares.

heatingpartswarehouse.co.uk

A generic replacement would probably be cheaper, but this has the fixing stud on the end, the correct connections and will fit into the space available.

There was nothing visibly wrong with ours, but it had partially failed so it was random whether the motor would start or not. It would sometimes go days between lockouts. From your description, I think it's quite likely to be the cause.

 

[reb78]

Have you bleed the pump? You,probably have but you didn't mention it in the first post, that can take quite a long time to get the air out. Theres a thermal cut out on the flow pipe on mine, I had air in the system that meant it cut out a few times, worth checking.
You could try rigging up a bottle of fuel to eliminate a problem with the supply side of things, like this.
View attachment 426645

We did bleed it. It ran for 24h or so after so assume air isnt the problem. I think as long as they start and arent airlocked they can cope with tiny bits of air?

 

[reb78]

Similar symptoms to mine when the photo cell failed, it's an easy test with a multimeter. I could be teaching you to suck eggs here but worth a check

We didnt test it, just replaced it. The plumber gets a fairly good price but it looks like I have a working spare now! And i will.test it to double check

 

[reb78]

It could easily be an intermittent fault with the igniter (or the controller - or anything). I'd swap igniter for a known good one.

Just change it, or you could use the capacitance range on your multimeter (if you/it has one).

This is the one that was in ours (Riello burner in a Firebird boiler - 4.5uF). I believe that there may be different values, so check the uF value against what you have first.

Riello Burner Capacitor, 4.5uF, 3002837, 20071576 | Buy at H.P.W.

Riello Burner Capacitor, 4.5uF, 3002837, 20071576 available to buy online, with fast tracked delivery. Heating Parts Warehouse the specialists in plumbing and heating parts and spares.

heatingpartswarehouse.co.uk

A generic replacement would probably be cheaper, but this has the fixing stud on the end, the correct connections and will fit into the space available.

There was nothing visibly wrong with ours, but it had partially failed so it was random whether the motor would start or not. It would sometimes go days between lockouts. From your description, I think it's quite likely to be the cause.

So I think, barring a weird fuel problem these two are next. I have a butner from a scrapped boiler that was working so will try capacitor first from that and then the whole control box.

@daedalusminos I assume you mean the ignition control module that I think is in the control box rather than another part downstream?

 

[jenki]

I agree with Onoff change the drive coupling and the capacitor, less than £20 delivered. These are the only things that have given trouble on my near 20 year boiler. As an aside I was suprised how stiff to turn the pump was I don't know if they are all like that.

 

[Onoff]

I agree with Onoff change the drive coupling

I had to buy 10 drive couplings, still dirt cheap (£5 ish?). If you get really stuck I'll post you one (if I can find them). The plastic breaks up. Like little wings that engage. Probably 3D printable as a stop gap.

Check any old fridges & freezers as you might get a capacitor off that.

 

[daedalusminos]

So I think, barring a weird fuel problem these two are next. I have a butner from a scrapped boiler that was working so will try capacitor first from that and then the whole control box.

@daedalusminos I assume you mean the ignition control module that I think is in the control box rather than another part downstream?

The module actually creating the high voltage (identifiable by the fact it'll have a car style HV connection) - on my sterling burner it's located on the butner itself

 

[reb78]

The module actually creating the high voltage (identifiable by the fact it'll have a car style HV connection) - on my sterling burner it's located on the butner itself

Cool. We are talking about the same part.

Have changed the vapacitor first as thats quick so will see how that does. Interestingly the one on it was a 4uF and the spare is a 4.5uF not sure that matters as it looks like both are sold for these burners.

 

[dobbslc]

As long as the voltage rating on the spare is the same or higher I don't think 0.5 of a farad will make much difference.

 

[Seadog]

I think that half a Farad would make a huge difference

 

[reb78]

I think that half a Farad would make a huge difference

I literally have no idea. It may do nothing, it may cause it to explode. Hence asking! It didnt explode btw.