pressure jet heater (Bubble)

[pete macson]

Hi all, my presssure jet heater is playing up - in short, it won't fire up unless i hit the reset button or reset by turning it off altogether - then it either fires and runs once or it runs fine for several cycles (until radiator/room temp reached) but then when needed again will only hum and not attempt to fire (unless i reset again) I previously replaced the transformer and capacitor as was struggling and has since been good but now this - any thoughts as i'm at a loss (thermostat, controller etc???) the red button flashes a lot and either locks out or stays red for 20 seconds or so before flashing again )or locking out) between cycles. When it does run it runs really well. Any help really appreciated.

 

[oilhead]

Burner motor humming is:
Faulty capacitor
Faulty motor
seized/sticking oil pump

 

[pete macson]

sorry, when i say humming it it coming from the valve 'switch' on the side that opens for hot water or radiators, The boiler itself is silent as such it just doesnt trry to fire even if it has just done a perfect cycle ( the thermostat in the room works perfectly and is still on (flame image showing so to speak. I.m at a loss. PCB board perhaps????

 

[oilhead]

Maybe the valve is not opening. Do you have details of this valve/switch?

 

[pete macson]

It's a Danfoss motorised zone valve - I'm not sure if it is relevant to the problem but when it is inbetween firing (when it no longer tries to fire up) the valve makes a humming noise and gets quite hot ? If this could be relevant to it not trying to fire I'll change it out, or would it do this if the boiler just didn't fire due to some other reason?

 

[oilhead]

An electrical test across the microswitch would confirm or eliminate the valve.

 

[pete macson]

OK, thank you for your help.

 

[pete macson]

One final thing Oilhead, on closer inspection the boiler does a perfect burn but on shutting down the burner stops and the fan/motor continues briefly but then there is a little click from the boiler which stops it followed by a louder click from the control box which seems to lock it out, hence it won't restart. Any thoughts as it cycles perfectly once until it clicks off at the end and then no more unless it gets reset?? I won't trouble you again, you've been very helpful. Pete.

 

[oilhead]

These symptoms you describe indicate loss of flame before the thermostat switches off. The control box is trying to recycle, but establishes no flame so locks out. I would suspect a faulty solenoid coil on the oil pump. What burner is this? The flashing red light will have a code analysis to aid fault finding.
If you have the patience, and a multimeter, then run it through a sequence, and when it stops, meter the coil terminals. If it is open circuit, then the coil is your problem.

 

[pete macson]

It's a PJ bubble pressure jet boiler (fitted onto a boat) so not a common household type - the red light is basic with no fault codes (satronic dko 992 pcb board). I'll try and look in to the solenoid if i get a chance at the weekend - would it still fire up after reset if it was faulty?? Thanks again.

 

[pete macson]

this is the solonoid and lead - will try to work out how to test it.

https://heatingpartswarehouse.co.uk/product/danfoss-bfp-oil-pump-coil-230v-071n0051/

https://heatingpartswarehouse.co.uk...ad-071g0204/?gclid=CKiGzd2R2OICFdX2UQodGJ8POQ

https://heatingpartswarehouse.co.uk...em-071n0050/?gclid=CKGD-4SS2OICFYhB0wodXOELGg

 

[pete macson]

Ok, have narrowed it down (I think) - when burner does first cycle then stops it either locks out or on it will fire up a second time but only for about 5 seconds then stall and lock out ( or try a third time for 5 seconds then lock out) - if i reset at the wall socket the burner turns over and locks out, then push the button for reset and it'll then fire up as described above. Solenoid or fuel delivery. Might have to bite the bullet and get someone in, was just hoping to fix it myself as normally very good at all DIY but this is a can of worms I'm failing to unravel! Final thoughts would be appreciated. Pete

 

[oilhead]

The boat installation puts a different complexion on your problem.
I think you will find the flashing sequence on the DKO control box relates to a status indicator.Bubble do not put this in their literature as they consider it 'too confusing for the end user'. (their words eight years ago!) I commissioned one of these for a customer on a boat and found it very fussy. Whilst the boiler is a bubble, you should find the burner will be a propriety item, either Bentone, Monoflame or EOGB.
Some more questions; Is it running on 12volt, 240 mains or 240 from an inverter? If 12 volt, then are your batteries in a good charge state? If 240 volt from an inverter, the control box may not like the sine wave it produces. Are you running on 28 sec (kerosene) or 35 sec (red diesel) ? If running on 35 sec, assuming the nozzle is a low throughput for a low output boiler, then it may be that the incoming fuel is to cold to atomise properly. Many domestic boilers that run on 35 sec have a nozzle pre heater to assist starting. I also found that the burner had a long post purge sequence, and that because the heat output was on the large side for the heating load, the firing cycle was little and often. This constant on/off plays havoc with the combustion, and the burner blast tube and diffuser quickly became carboned up, and clouded the photo cell. If the photo cell does not see the flame, it will run to lockout. Also, which photo cell is fitted? The regular MZ is not fully compatible with the DKO box.

 

[pete macson]

Wow, you really know your stuff - for the record its 240v from shore power. Anyway, good news, I took your earlier advice about the solenoid and fitted it today, wehe, it worked from the off. Ran it an hour for hot water then left it a couple of hours before running it again for the radiators and again ran like a dream, Thank you for your help, I wasn't looking at the fuel supply area as it was getting fuel - I was going to buy a new actuator until your advice so you've saved my both time and money and made my other half very happy (she came back from work and soaked in a hot bath!). Thanks again, Pete.

 

[oilhead]

It' great when a plan comes together! Happy to help, and thanks for letting us know the outcome.