worcester bosch heatslave 15/19 oil fired - lockout mode

[cjard]

hi guys

the oil pump is a bfp41s, the contrller unit is a bentone 832.3

i've read a few posts on the topic and gathered a list of things to check.. but here are the symptoms if anyone can give a targeted advice:

i set the heating and hw to On then press the lockout reset button, there's a noise like a fan running, a noise like a motor (like a freezer compressor) and a rapid buzzing which i'd guess is the igniter and a few seconds later a boomph noise as the boiler fires.
it runs and produces hot water for some random amount of time that seems to get shorter the more i press the reset button (something electrical geting hot and failing?)
after this random amount of time there's a rapid clicking like a solenoid or relay opening and closing(though i can't tell whether it's one or several relays) for about half a second and the buzzing (of the igniter?) is heard for an extended period of time (longer than the first time)
the boiler doesnt seem to fire and goes into lockout mode

the boiler owner says it was serviced a few weeks ago, but it hasnt been used much since-this is a holiday rental property

thanks in advance

 

[holty]

i would say a classic solenoid problem gradually breaking down.only way to diagnose is using a multimeter and when it goes into lockout.take the lead off the solenoid and check both upper pins for resistance.p.s switch the boiler off before hand when testing.think you should be reading around 200 ohms.

 

[djsarge1973]

If the boiler runs when everything is cold...then once it gets hot,shuts off then it sounds like the Solenoid is losing it's magentic field, a quite simple fix... all you'll need is a 2.5mm allen key & a "BFP Coil set" should take about 10 mins all in all to change

 

[cjard]

i would say a classic solenoid problem gradually breaking down.only way to diagnose is using a multimeter and when it goes into lockout.take the lead off the solenoid and check both upper pins for resistance.p.s switch the boiler off before hand when testing.think you should be reading around 200 ohms.

I let the boiler sit over night, then in the morning tested the resistance: open circuit
I fired the boiler and waited til it went into lockout mode, then tested the resistance:
open circuit again

Is it likely that things have broken down to such an extent that 240v AC (if that is what is supplied) can flow for a while, but the puny DC voltage from the battery in the multimeter cannot?

 

[Burnerman]

The Danfoss solenoid coil, part number 071N0010, has a 240v AC coil.
Its resistance across the coil is 2k to 2.1k ohms cold.
Measure across the two terminals that are parallel - they could be marked A1.
John

 

[cjard]

hi burnerman

I measured the resistance across all pins (because i wasnt sure, at the time, which to measure) using the continuity mode (beep) of my multimeter because it also does auto range when in that mode.. and all pins were open circuit/infinite resistance.. this had me confused, unsure how the component could work at all?

 

[Burnerman]

2000 ohms is too high for a beep on the multimeter......it needs to be set on a range higher than this. You'll get infinite readings otherwise.
Measure the resistance across the 2 pins that are parallel to eachother, ignore the third one.
Coils are around £30 - a bit steep really considering you can get a complete pump with coil for £70 or thereabouts.
John