Potterton Netaheat 16-22

[pixey]

Hi. I have an intermittent problem with the above boiler, only it is getting worst.

My system is fully pumped y-plan. Pump is ok.

When the boiler is switched on, the fan starts up and after a few seconds, the pilot lights. The problem is that the main burner will not light. It doesn't come on and then go out, it does not light.

The fan remains on and so does the pilot. I think you can hear a faint clicking noise, sounds like a an ignition spark, but that is all.

The boiler will remain in this state for hours if not turned off.

Usually you can get it to work by turning it off and back on, but it is getting harder to get the main burner to light.

Any help greatly appreciated.

Paul

 

[ChrisR]

Haven't we seen this question recently?
Answer is to get a corgi though, definitely.

 

[pixey]

Thanks chrisr, not the answer I was looking for.

Anyone with anything more constructive would be appreciated.

 

[ollski]

Go on then what answer were you looking for?....this boiler is called the widowmaker and is generally corgi territory. There are some checks you can through with a multimeter though to pinpoint it to maybe the air pressure switch or the gas valve......do you have one?

 

[pixey]

Following the flow chart in the back of the install manual, it says there should be 240v across T1 & T3 on electronic control. I do not have 240v here and it says " suspect control box". Anything inside that I can check - I have a B-Tec in electrical engineering.

Thanks

 

[ChrisR]

OK as long as you don't take the cover off the boiler.

Power off, remove wires from t1 and t3 and check there's a resistance between those wires. Something like 500 - 1500 ohms, can't remember exactly. If there is, then the control box looks dud.

 

[pixey]

ChrisR, testing away from t1 & t3 (the wire) tests 4.3k and into the board tests 155k.
I powered up the boiler with the bottom panel off and after the pilot is lit there is a faint clicking sound coming from under the black protective cover on the cct board. When I lifted the cover there is a glass component labled SG1 that "lights up" like a bulb each time there is a faint click.

It doesn't look normal to me but I don't know what the component is.
Do you know if this is normal and what the part is??

Anyone else know what the component could be??

 

[ollski]

Is that the one with the big replaceable relay?, sounds like it.

 

[pixey]

Is that the one with the big replaceable relay?, sounds like it.

Do you mean the cct board with the big replaceable relay? I don't know, I suppose so, there is only one cct board isn't there?

 

[Agile]

You have an electrical qualification and you dont recognise the component? Even with the clue SG1 ??

Its a spark gap !!! It remains non conductive until the voltage across it is sufficient to ionise the gas in it and then it conducts as if with a resistance of about 20 ohms.

Its used to discharge a capacitor into the EHT transformer and generate the spark!

The fault is caused because the boiler is not recognising that the flame has lit. Either the flame is not illuminating the electrode or the circuit is faulty, probably the latter!

Tony Glazier

 

[ChrisR]

No it's not the one with the relay. As our friend hasn't told us which of the 5 or so 16-22's it is I checked for a fault finding chart. Only one I found which gets to look for 230v on t1 and t3 (GV conns) is an Electronic, AFTER the spark has stopped sparking.

SO, pixey, does the spark stop sparking? If not, you misread your FF chart (?), and the next stage means taking the case off unless you can see a dodgy wire outside it, which we do not advise you do.

 

[Agile]

His first posting said:-

"""The fan remains on and so does the pilot. I think you can hear a faint clicking noise, sounds like a an ignition spark, but that is all.

The boiler will remain in this state for hours if not turned off. """

So it continues sparking and evidently does not think the pilot has lit!

Presumable one of the later models with proper pcb ???

Has the lady in Kingston contacted you about a replacement for her Neta ???

Tony Glazier

 

[ollski]

Just had a quick look at the mk2 16/22, that one has definitely got a honking great relay on it.
Edit: I've looked at all the 16/22's they all have a relay except the electronic mk1

 

[ChrisR]

OIlski yes I know but it the 2F doesn't give the fault finding chart he's using!
Also the spark generator is a separate pcb/module on the pre-electronics, you can't see the flashy spark gap, it's on the one board (same board as Profile etc, different connectors)
The "Electronics" don't have the relay.
SO it's perfectly clear, er, isn't it?

Tony no she hasn't.
And yes I know that's why I suggested he'd misread his fault finding chart, he would only have got where he said if it had stopped sparking, so it couldn't have stopped sparking, which tied up with what he said, which is why I said what I did!

All perfectly clear - the thing probably needs a service!

 

[pixey]

You have an electrical qualification and you dont recognise the component? Even with the clue SG1 ??

Its a spark gap !!! It remains non conductive until the voltage across it is sufficient to ionise the gas in it and then it conducts as if with a resistance of about 20 ohms.

Its used to discharge a capacitor into the EHT transformer and generate the spark!

The fault is caused because the boiler is not recognising that the flame has lit. Either the flame is not illuminating the electrode or the circuit is faulty, probably the latter!

Tony Glazier

No Tony I don't recognise the component, but boiler electronics are not my thing, that is why I asked.
I take it that the "spark gap" is behaving normally then?
The pilot is lit. Is it the job of the spark gap to light the pilot not the main burner?

ChrisR, "I know that's why I suggested he'd misread his fault finding chart, he would only have got where he said if it had stopped sparking, so it couldn't have stopped sparking, which tied up with what he said, which is why I said what I did! "

The ff chart says if there is no 240v across t1 & t3 suspect control box and replace, so how can I have misread it?
Oh I see, if I answer the question "does spark stop" - no, it asks " does pilot flame engulf electrode?"

So I assume SG1 must be the trigger to light the pilot??

Are there any other electrical checks that I can do to or anything at all without removing the cover (which I don't want to do)?

If I answer the above question yes, the flame does engulf the electrode, it then says,"check polarity on input terminal" . Input terminal where? Can this be done with the cover on?

Thanks for your help so far, and btw, it is an electronic.

pixey