Flame Rectification | How To Test | ACS Gas Learning NGCFE

[@AnthonyFrancisJones]

Excellent and well explained. A couple of comments - firstly I would never dial through the multimeter settings whilst connected to a live circuit - turn off or disconnect the meter. You will usually get away with it but you can blow fuses in some meters (believe me with students I have changed 100s of them!). Secondly there is the usual confusion about voltage (across) and current/amps (through). It does not really affect the understanding here. For the very observant connecting the meter in series and measuring a voltage - you were lucky that things still worked as normally meters will pass almost no current at all at this setting as an 'ideal voltmeter' should be an infinite resistance/break in the circuit, but the currents are so low you get away with it here. Only comments - not a criticism at all. Your explanation was excellent!

[@AllenHart999]

Thanks very much for your comment, please consider subscribing to support the channel 🙂

[@StrixTechnica]

Plus, many multimeters require that you plug the +ve lead into a different jack in order to measure current.

[@AnthonyFrancisJones]

@@StrixTechnica Yes, especially if it is a high current. I have worked a lot with meters that use shunts (I know not true multimeters) and swapping a voltage shunt for a current one in-circuit can be a mistake!!

[@StrixTechnica]

​@@AnthonyFrancisJones Not sure what you mean by 'true' multimeter, but anyway: yes, switching to current measurement when measuring voltage (especially of a low impedance voltage source, which is probably the majority of cases) is definitely a mistake. But it's (usually) safe enough the other way around because all you're doing is inserting a large impedance where there was none before.

[@AnthonyFrancisJones]

@@StrixTechnica Yes, exactly. Sorry, what I meant about a 'true' multimeter is the the ones that I use in the lab to teach with are multi-range but are actually single meters where you have to plug and unplug specific shunts to define what they measure. It enables you to have one type of meter and a range of separate fixed plug in shunts that means you can pre set them up for younger students. Older ones get a 'genuine' multimeter with a rotating dial that does the work for your (and then they blow the fuse!)!

[@adilrashid5283]

Allan Hart how did he set the multi meter probes on the rectification leads

[@niazkhel1839]

Thats measuring “potential difference” and that meter is very good to have only 2 ports to automatically switch between parallel & series circuit. For the older meters you have to take out the probe and slot it into the common and the Amp symbol. The flame converting into DC is science, I love this stuff. Not only will you get burnt but get a shock (if current was right). Would discovered this ? Epic! The video is great in fault finding. Would like to see these readings in manufactures servicing booklets so we don’t have to keep calling them for it.

[@dannymatona3506]

Very helpful. Made more sense to me today, than it did last week. Good insight

[@karlnoonan5597]

Excellent video, thank you both.

[@jockster5525]

Class act here ..many thanks for your efforts lads 👌😎

[@ivanondov8826]

Really good video. Explains it perfectly cheers guys 👏👍

[@vipergas5542]

Great Video Allen / NGCFE 🔥👍🏻

[@markthompson4178]

Really good video. Explains it perfectly cheers

[@AllenHart999]

Glad it helped

[@vishalchain]

great explanation but it would be great to see how he connected probs .. can see the reading but it would be helpful to see how he attached probs too thanks :)

[@JamienM]

Great video! Learned a lot thanks

[@tp65857438]

Can you please explane how to test that same probe on worchester 24i rsf combo? Thanks ahead.

[@luke_the_plumber]

this video is been a missive help in understanding flame rectification for my MLP/ and ACS preparation do you have a video demonstrating the basic principle of gas controls? thank you

[@olitonottero7620]

very helpful thanks

[@sushilkumar-kl4ok]

How to check high efficiency furnace or low ?

[@MrHandymon]

A voltmeter is never used in series with a circuit, as this tells you nothing, other than the volt drop across the meter itself, which will vary from meter to meter depending on its internal resistance (ohms per volt). The only way to properly check this circuit is with the ammeter in series (as shown) or the voltmeter between ground and the ionisation probe, though the voltage shown on the meter may be ambiguous due to it been half wave rectified.

[@johnburns4017]

Correct.

[@michaelhunt848]

Thanks for the feedback guys. Always happy to learn from other engineers. Just a question. If the flame wasn’t present, would you still get a Vdc reading? Totally agree that micro amps is how most manufacturers suggest that this test should be should be carried out. It’s just a shame that only the high end (and priced) multimeters have that setting.

[@MrIsrar626]

Very true, the meter in the video is connected in series and yet set to volts dc, I don’t think the reading shown on the meter is of much value from a diagnostic perspective. Good demo otherwise.

[@johnburns4017]

@@MrIsrar626 Digital meters tend throw up a lot of display garbage at a times, unlike the old analogue meters. For some uses some guys still use analogue meters. The meter in series, as been noted, does read the amps. If you do not know what the AC voltage to the flame rectification probe should be or the DC voltage coming back. Just reading that there is AC going to and DC coming back, gives a ballpark indication that things may be working OK on the probe side. That would mean reading the voltages correctly.

[@AnthonyFrancisJones]

Agreed! Do you think that the internal resistance of the meter was such that it could still pass a few uA when in voltage setting so the circuit (luckily) still worked?

[@CommercialGasEngineerVideos]

Cool. Nice video. Some boilers have the capability of showing you the flame strength.

[@plumbertime]

Like that exact boiler you mean 😂! Coz that one does! It’s in the menus think anything under 35 is suspect but check the book!

[@adamprice6415]

Anything under 400

[@Zaine22]

Would have been nice to see how he set the multi meter up

[@teplotehnikaspb]

👍

[@FLYNN..]

A video on 16.9 would be a good.

[@MichaelATH]

Really to get your electrical terms in line, your mixing things together. you can’t have 100v of ac current . You can’t put a meter in series and check voltage. You can’t have. 63 volts of dc current. I understand where your going with it, but it’s really going to confuse someone who’s unsure.

[@AllenHart999]

Thank You

[@farukadam1696]

Hi Allan Good video Only engineer voice is lowest Regards Faruk

[@johnburns4017]

The test with the multimeter at 6:40 was not the _return_ to the pcb. It was the _supply_ to the flame rectification probe from the pcb. The return is the green wire. Did I get that right?

[@AllenHart999]

You are correct in what you are saying but this is reading the circuit. Thanks.

[@johnburns4017]

@@AllenHart999 It is *AC* current *to* the flame rectification probe from the pcb. The flame changes the electrical voltage from AC to *DC,* as it conducts through the flame, then it returns back to the pcb. The meter is a Fluke 116. The setting _was_ on DC. I can only assume there was a reading of DC as the multimeter was connected in *series* by Michael to read voltage, which is not how you read voltage.

[@dannydobson2675]

Does it rectify with temperature of the flame?

[@johnburns4017]

@@dannydobson2675 Not that I am aware of. The flame acts as a diode. Goes one way not the other. The DC will be pulsating DC not pure DC like out of a battery. The setting on the multimeter indicated pure ( - ) and pulsating (- - -) DC.

[@macpatel7810]

I am a bit confused about that too. I thought he said the probe is AC and the green earth wire carries the DC current back to the board. I too am missing something.

[@gerrycoffey1]

Allen different types of heat exchangers. Japanese Korean and European and American. Positives and drawbacks

[@joemurgatroyd7174]

10 quid says the burner gasket needs changing

[@restaurantjackerofficial3777]

Hi Allen could u just talk us through where the actual multi metre probes went .I know u had a crocodile clip on the red but where did u put the black .its quite hard to see the top of boiler .thanks