Worcester heatslave 15/19 issues

oilhead said:
If the cell sees light during prepurge, surely it won't light as the solenoid is not opened. What is the number on the White square Danfoss control box? Is it a BHO11 or 12 , 57H1, or a BHO61?
I can't recall ever seeing anything other than Satronic boxes on Heatslaves, and if someone has substituted along the way, this may be a mismatched cell and box.
Click to expand...
If the Cb sees light during purge it will fire and lock out.
If you have worked on older burners with no solenoid, ZLO etc The motor is wired to the sol coil terminal to prevent this when a new box is fitted.
 
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I'm not near the boiler at the moment to check the control box number but it certainly looks contemporary with the burner and boiler.
This set up has been working for the last however many years with no significant problems so unlikely to be a mismatch of components?
 
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oilhead said:
If the cell sees light during prepurge, surely it won't light as the solenoid is not opened. What is the number on the White square Danfoss control box? Is it a BHO11 or 12 , 57H1, or a BHO61?
I can't recall ever seeing anything other than Satronic boxes on Heatslaves, and if someone has substituted along the way, this may be a mismatched cell and box.
Click to expand...

Terrywookfit said:
If the Cb sees light during purge it will fire and lock out.
If you have worked on older burners with no solenoid, ZLO etc The motor is wired to the sol coil terminal to prevent this when a new box is fitted.
Click to expand...

I don't think I've understood you 2 correctly:(

If the cell sees light during pre-purge will it still continue through the rest of the normal start sequence, fan, solenoid, ignition, injection and then burn, followed by lockout?

This is the sequence that's happening regardless of whether the cell is in the housing or out which suggests to me that it's either the cell or the ability of the control box to interpret the cell that's the problem.

Hope this makes sense lads :sneaky:
 
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Terrywookfit said:
If the Cb sees light during purge it will fire and lock out.
If you have worked on older burners with no solenoid, ZLO etc The motor is wired to the sol coil terminal to prevent this when a new box is fitted.
Click to expand...

Just had another thought!!

How much light is too much light for the cell prior to start up?

This cell has a hard plastic flange to hold it in place but there's not a seal behind the flange. The hole in the burner is larger than the cell with a recess which under other circumstances I'd expect to see an o ring or similar. So some light will get through to the chamber the cell sits in.
 
Terrywookfit said:
A photo of the burner would be good.
Click to expand...

It's on my growing list to do as soon as I get there (y)

I've also got to find the control box part number as danfoss list a few variations of the modern equivalent with different functions included.
I haven't seen part number on the cell up to now which won't help me.

I will re-do the torch test as it should be done if the resistance readings are in the ball park. If that works well I'll seal the gaps around the cell to try again. Just in case :)
 
At 18 years old, the 15/19 would have had a B9 or B11burner and both of these would have had Satronic boxes. I think it would also have been too late for the TF801 series box which would have had the FZ cell referred to by Terry. If the photocell is loose in the hole, then if an FZ has been replaced with an MZ, then this can produce the fault the OP has. I recently attended a burner with the TF801 series box and the FZ cell which had failed, and the MZcell was very hit and miss. After changing for a TF830, then no problem. When we get the numbers, we may be better advised.
Sorry Terry, yes, the burner will light on these boxes then lock out. I know there are other burners ( Riello) where they stay in prepurge for a long time before locking out.
Reading the original sequence again, it is not clear if the burner fires immediately or whether it prepurges first.
 
IMG_20210406_151711.jpg IMG_20210406_151447.jpg IMG_20210406_151314.jpg IMG_20210406_151743.jpg

To confirm the sequence, at 1st reset after lockout it pre-purges ? (just fan running) for apx 4 seconds then burner lights. Apx 8 seconds later lockout again. If it's reset after the 2 minute wait sometimes it just lights straightaway with no pre-purge?

I torch tested the cell with it fisted until burner lit. No different to any other sequence.

Took resistance reading through cell and it's as follows. My multimeter has a range of resistance settings and I tried them all both dark & light. The only 2 ranges that read anything other than open circuit were 2M & 200K.
Readings were never very steady at all.

2M dark .600, light .084
200K dark open circuit, light 80.0

I spoke to a supplier who then spoke to danfoss this afternoon, expecting you to tell me the cell is dead, and the news is that both CB & cell were superceded a long time ago and there's an update kit available.
 
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Terrywookfit said:
https://www.google.co.uk/url?sa=i&url=https://www.electronics-tutorials.ws/io/io_4.html&psig=AOvVaw1bOg7gRykht52imcKIHc_Y&ust=1617872938237000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCKDVmMDk6-8CFQAAAAAdAAAAABAD
Click to expand...

Thanks for the link, I had read a similar page previously.

Unfortunately I didn't have an autoranging meter with me so I'm left a bit in the dark with the results.

Would you say that 0.6M is high enough for a dark reading and 80K low enough for light reading?
 
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