Then the manufacturers are at fault. Agile seems to be better informed.
As to the "bodge" of concealling a bridge rectifier in the lead and "forgetting" to mention it. Beggars believe, but then people who make boilers seem to lack some basic electronic knowledge.
How does the DC coil in the gas valve like being fed raw DC ?
The DC output from a bridge rectifier fed with 50 Hz AC is raw DC, that is DC but pulsed at 100 pulses per second.
Hence the magnetic field in the gas valve solenoid is pulsing at 100 pulses per second. Mechanical inertia of the mechanism seems to prevent the gas valve opening and closing 100 times a second.
If the solenoid in the gas valve is not designed to withstand continuous pulsing by raw DC then the effect of the pulsing on the winding of the coil may be significant and may lead to premature failure of the gas valve solenoid.
That said it might be just a single diode and the gas valve is being fed 50 pulses and 50 gaps per second. Even worse.
This applies to any coil designed to be operated by smooth DC coil but fed with raw DC.[/QUOTE
So tell me what good is that information when you still have to replace the lead anyway , you've got to know it's in there first of which a lot of manufacturers dont tell pertinent info ( or wrong info )@anyway and people wonder why we tell them to leave it to an engineer and they get shirty about it
Vaillant thermo compact 615e
- Thread starter S_cambo
- Start date
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How did agile add that diagram after quite a while after writing it ,when it shows it hasn't been edited .
Hey agile
Hey agile
agas said:So tell me what good is that information when you still have to replace the lead anyway , you've got to know it's in there first of which a lot of manufacturers dont tell pertinent info ( or wrong info )@anyway and people wonder why we tell them to leave it to an engineer and they get shirty about it
Explain how, if the manufacturers do not mention it, that an engineer will know that changing the gas valve will require the lead to be changed as well. If the old lead plugs into the new gas valve what is there to suggest to the engineer that the old lead has to be replaced as well as the valve.
Possibly the engineer will get the information but only by discussing with other engineers why a simple gas valve swap did not repair the boiler.
( there is a ] missing from your post hence the quote didn't work )
How did agile add that diagram after quite a while after writing it ,when it shows it hasn't been edited .
Hey agile
That was because I had to look for a suitable circuit diagram.
If you have written and then edit the LAST post in a thread, then the system does not indicate an edit.
An edit only shows if there has been another reply!
Tony
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The gas valve is fed with raw DC from a full wave rectifier.
The current taken is quite small and is smoothed by the inductance of the gas valve solenoid. So it is not necessary to smooth the raw DC.
Most boilers have the bridge rectifier supplying the gas valve fitted on the boiler's PCB. A very few have it encapsulated in the lead, only Vaillant and Baxi/Potterton, have some of those models as far as I know.
I am sure that all Vaillant staff engineers are well trained on this topic. It has been covered several times in the closed CC section of this forum.
Don't know why Bunnyman, who should be well aware of it, has made those odd comments above!
Not necessary only if the coil is designed to accept raw DC. The problem with coils fed with raw DC ( or AC ) is the motor effect on any loose turns in the windings. Changing magnetic flux and current in the wire creates a force trying to push the turns apart. This results in vibration of loose turns windings and subsequent abrasion of insulation and creation of shorted turns inside the winding
None of those effects will occur.
Those effects are only caused by a changing magnetic flux.
In the case of gas valve solenoids fed from raw DC their inductance results in a virtually pure DC current.
The high inductance is a byproduct of their construction. But a useful one as it avoids the need for a smoothing capacitor!
Those effects are only caused by a changing magnetic flux.
In the case of gas valve solenoids fed from raw DC their inductance results in a virtually pure DC current.
The high inductance is a byproduct of their construction. But a useful one as it avoids the need for a smoothing capacitor!
,
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Are you sure it's pure DC current ?
And the magnetic flux will vary as the coil's inductance generate back EMF changes to oppose the changing DC voltage applied to the coil.
An inductor ( in choke coil mode ) together with the necessary capacitors can create a filter that converts raw DC into a smoothed DC supply.
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