Worcester Bosch Heatslave 15/19 Intermittent Lockout

[stevecook]

Worcester Bosch Heatslave 15/19 Intermittent Lockout
First started mid Nov 2008. Any time of day but commonly first thing am. OFTEC boilerman serviced it and told me whilst ever it restarted on the reset button it would be like trying to find needle in the proverbial. He said he could try changing parts one by one, some cheap, some not so, eventually find problem but a lot of cost involved and was trying to save me money so advised to bear with the problem, hopefully break down properly then easier to find what's at fault. If he couldn't find problem then would at least be able for him to use WB technical helpline to faultfind. I reluctantly accepted advice but when it became so regular, about 10 times a day, he suggested that I might try changing Satronic controller as this was within my novice scope. I duly did with no success but he'd mentioned the coil/solenoid in passing and I'd read an old post talking about coil probs with Electro Oil burners so I changed the coil and Hey Presto no problems for 2 months until last week when it's started again!
A couple of times a day at the moment, first thing in morning for last 3 days and once or twice later on in day. THe only other things of note

1. Oil running quite low last week when it restarted but still 100cms above sight gauge. Refilled tank, still happening so could feed be a problem (air or dirt)?
2. When I've been around on lockout there is strong and hot fuel smell from boiler. Normally little or no smell.
3. Photocell seems clean
4. Whole system is 15 years old. 2 oil pumps in that time last one 2004. New burner motor 2004
5. Danfoss 0.50 80EH nozzle

Sorry about the long description. Hope somone can point me in right direction if you've not fallen asleep already

Steve

 

[OilLecky]

Eliminate Oil supply first. Making sure that you have a container underneath, if you have paper fuel filter elements, renew them, if you have plastic ones clean them. Check that there is no water in the filter bowl. Turn the oil off in the boiler & remove the filter from the fuel pump on the burner. Some pumps you have to remove the end cap with an Allen key, others have a filter with a picture showing where it is. Clean it and refit. With the oil off , remove the fuel inlet pipe from the pump, crack the oil valve open and make sure that you have a good oil flow.
Get that done and then we'll get on to the more technical bits. Do you have or can you get an electrical multimeter?

 

[oilman]

It seems like it is getting oil, so it could be electrical. If it is locking out when cold, it suggests the pump solenoid coil is ok. If it locks out at totally random intervals, it suggests the ignition "transformer" is faulty, but you would need to confirm the electrodes are not sooty.

 

[stevecook]

Thanks OilLecky and Oilman for quick reply. Forgive my stupidity but I can't see any obvious fuel filter. The copper piping enters the house at floor level within the boiler to a brass thumbwheel and thereafter continues as reinforced flexible hose into side of oil pump which incidentally is a Danfoss BFP21L3 and, you guessed it, I can't see where the filter is situated in that either. Sorry! On the multimeter, no I haven't got one but can surely get one in, either borrow or buy.
Since I first posted I've noticed several occasions when the boiler goes to reignite the normal whirring noise of the fan/pump is absent, the only noise a faint electrical buzz which ends with the lockout. Gave me impression of something sticking so the next time it happened whilst I was standing over it I tapped the end of oil pump with my knuckles and it fired. I'm sure that is not an advisable procedure and subsequent ignition was probably a coincidence. Does any of this mean anything to anyone?

 

[oilman]

Oil filter may be near the oil tank.

Buzzing may be the spark, or it may be a worn coupling behind the oil pump. You need to remove the connection to the thin nozzle pipe, then 3 allen screws hold the pump to the motor. Undo these and withdraw the pump. The coupling is on the end of the shaft.

 

[stevecook]

I did check back along the line towards the oil tank but still no sign of any filter system, not that I know exactly what it will look like but just copper tubing seems to be all there is!
As for removing oil pump I'll have to leave it till tomorrow pm but I think I see what I have to do. I need to isolate oil and mains I assume? Will wear be obvious to the untrained eye?

 

[oilman]

As long as you don't touch the inlet pipe, there won't be a problem. As for wear well.......

 

[stevecook]

Thanks, I'll let you know what happens.

 

[OilLecky]

Steve. Oilman is correct it did seem as though you were getting oil. I wanted to make sure that the oil was was clean and flowing well before we moved on. ( I've had a good few lock-outs during the cold spell caused by water in the fuel.)
Now that you have heard the noise, probably of ignition, but the pump /fan wasn't turning, it narrows things down a bit. I doubt that it is any of the drive dogs worn as then the motor would run on its own. Either it's a partly seized pump, partly seized motor or the motor capacitor faulty. The motor capacitor is the little tube thing on the side of the motor with two wires going to it. I vote for the capacitor first, a) because it's job is to start the motor turning and b) its cheap!
( I did find one once where the wires were wrapped around the capacitor terminals instead of soldered!) Make sure that you electrically isolate the boiler and short circuit the capacitor terminals by using a shorting link or a couple of screwdrivers before you touch or disconnect it!! Also make sure that all the electrical connections in the control box are OK.

 

[OilLecky]

Steve, I've been thinking that Oilman could (yet again!) be quite correct. If the coupling between the motor and the pump has distorted rather than sheared, then it could be stalling the motor. Your judicial tap got it going again. Normally to get a motor going with a duff capacitor you have to spin the fan by hand. ( not recommended for those with slow reactions.)
Do as he says first and take the pump off to check the coupling for wear. also check the motor drive shaft. You may need to clean any distortion / burrs up with a small hand file.

 

[stevecook]

Thanks OilLecky for your replies. Unfortunately work has kept me from getting my hands dirty this evening and doing what Oilman suggested but will get to it first thing Wed am. Still can't find an oil filter between tank and oil pump. Surely I need to put one in at some point?

 

[Tipper]

The filter could be at the bottom of the level tube if you have one of the combined tube/valve/filter gizmos.

 

[Burnerman]

The BFP21 pump has a metal gauze filter underneath its end cap, accessed by removing 4 allen screws. I think I would run the motor on the bench - it should freely rotate by hand, and start to spin immediately when switched on. If it doesn't want to turn, try turning the spindle by hand and switching it on at the same time.....if the start windings have failed, this will get it spinning. An AC motor needs the start windings to get it going...if they have failed, the motor tends to pulse at 50hz and doesn't have the impulse to go in the correct direction of rotation. Cheers John

 

[stevecook]

Have removed oil pump and oh dear! Forgive my ignorance of the correct terms but this what I see. Full of powdery oxidised crud. A 1 inch shaft coming out of pump with two keys diametrically opposite which are the source of said crud because they're almost totally worn away. This shaft turns reasonably easily by hand. Within the motor end I think is a bushing with two matching keyways which have also sustained considerable wear.
This part turns the motor very freely by hand. Obviously parts need replacing but does that mean both pump and motor or can these worn bits be replaced separately?

Steve

 

[stevecook]

On further investigation I find the eroded keyed shaft on the oil pump is a removable plastic 'top hat' not metal as I thought (you all knew that already I'm sure) and I assume a replaceable 'weak link' of the motor assembly. That still leaves the eroded metal keyway bushing within the motor that the 'top hat' mates with. The pump spindle has a flat section which has worn/rounded on the leading rotating edge but threequarters of the flat section remains intact.