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Alde 2928 continually sparking


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Hi

 

Been refitting our NB, and in the process of putting things back.


Reconnected the electric to the Alde 2928, which hasn’t been used for probably 2 years, it is sparking every second or so like it would when I want to light it. Turning the dial to off, I can hear the mechanical switch click, however it still continues to keep sparking. There is no gas switched on at this time, so don’t know if it would stop when lit. 
 

Only way to stop it sparking is to cut the 12v feed.

 

Anyone have any ideas what the problem could be?

 

Thanks

 

 

 

 

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There's a cam on the bottom of the control knob which moves a lever which in turn operates a microswitch which switches power on to the spark transformer when the knob is moved from the off position. Once the flame has been detected the system cuts the power to the transformer. So if your spark runs with the knob in the off position it's most likely the microswitch needs adjusting. It's mounting bolts run in slotted holes to facilitate the adjustment. It's fiddly to get it right, but not difficult, although you might have to try it 2 or 3 times to get it behaving properly.

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1 minute ago, MtB said:

Is there not a thermostatic temperature control on the gas valve too?

 

Yes, it's the knob that has the cam under it David Mack explained. It has a ring of numbers around it plus a star and lightening flas if I remember correctly.

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2 hours ago, Nemysys said:

Thank you, very much appreciated.
 

Since asking, I have found online a technical manual and one of the troubleshooting articles says exactly the same. 

Hope that is all it is.

 

Could you put up a link for this please.

 

Bod

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19 hours ago, Nemysys said:

Hi

 

Been refitting our NB, and in the process of putting things back.


Reconnected the electric to the Alde 2928, which hasn’t been used for probably 2 years, it is sparking every second or so like it would when I want to light it. Turning the dial to off, I can hear the mechanical switch click, however it still continues to keep sparking. There is no gas switched on at this time, so don’t know if it would stop when lit. 
 

Only way to stop it sparking is to cut the 12v feed.

 

Anyone have any ideas what the problem could be?

 

Thanks

 

 

 

 

Mine also continues sparking even after its lit.  I'd be interested to know if and how you manage to fix it.

 

Ta

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13 minutes ago, Tony Brooks said:

When mine did it, it was the igniter. It senses the resistance to the spark, so when the spark is in a flame the resistance drops, so the igniter turns itself off - or something like that. It senses the resistance of a flame.

Nearly.  The flame is ionised gas which conducts, continually discharges the capacitor in the igniter box so that it never builds up sufficient charge to discharge across the gap. I'm a bit of a pedant these days! :offtopic:

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4 minutes ago, Tracy D'arth said:

Nearly.  The flame is ionised gas which conducts, continually discharges the capacitor in the igniter box so that it never builds up sufficient charge to discharge across the gap. I'm a bit of a pedant these days! :offtopic:

 

There are at least two completely different flame detection technologies used in boilers (neither of which I fully understand!) This method has fallen into disuse because soot, debris or a short circuit on the spark electrode can lead to the flame detection being satisfied and the spark stopping, despite the flame having gone out. The other method (known as 'flame rectification') can tell the difference between absence of a flame, and a short circuit. 

 

But whichever method is used in the Alde, if the pilot flame is too small (common with lack of servicing) or in the wrong place, then the spark will continue to spark even when the flame is alight.

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13 minutes ago, MtB said:

But whichever method is used in the Alde, if the pilot flame is too small (common with lack of servicing) or in the wrong place, then the spark will continue to spark even when the flame is alight.

Until I cleaned the burner I sometimes had the situation where the igniter would continue clicking with just the pilot alight, but stop when the main burner fired.

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As commented elsewhere, ignition of the Alde is very dependent upon the correct adjustment and operation of the microswitch. If you've tried to adjust it you will know how to get at it.

So, why not cheat? Many of us have.

Bypass the microswitch and install a handy 12v manual switch. Then you just need two hands for the ignition sequence rather than one. Turn the control knob to the 'spark' position - operate your switch - wait for ignition (you should be able to hear it) - turn off your switch - hold the control knob until the thermocouple is warmed up - turn the control knob to the desired setting - switch on pump. A pilot lamp in circuit can be handy just to confirm you are getting a good far spark.

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3 minutes ago, Opener said:

As commented elsewhere, ignition of the Alde is very dependent upon the correct adjustment and operation of the microswitch. If you've tried to adjust it you will know how to get at it.

So, why not cheat? Many of us have.

Bypass the microswitch and install a handy 12v manual switch. Then you just need two hands for the ignition sequence rather than one. Turn the control knob to the 'spark' position - operate your switch - wait for ignition (you should be able to hear it) - turn off your switch - hold the control knob until the thermocouple is warmed up - turn the control knob to the desired setting - switch on pump. A pilot lamp in circuit can be handy just to confirm you are getting a good far spark.

 

I don't fully understand what is proposed.

 

The pump and the whole heater is switched via the thermostat switch, not one on the heater, unless perhaps it has the optional mains heater, so I don't understand what the pump switch is unless it is the actual thermostat.

 

By all means replace the switch on the thermostat that controls the whole heater with a separate one, and adding a pilot lamp to know when it is turned on won't do any harm, but I am not sure how it will tell you that you have a good spark.

 

We don't know for sure which tall Alde Opener has. Some earlier ones did, I think, need two hand to light (gas valve and igniter button). I  am sure my 2928 only needed one hand to ignite once the thermostat switch was turned on. Turn the control knob to the star or lightening flash position and push down to open the gas valve.

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"I don't fully understand what is proposed."

 

I know what I mean!! Never was too hot on explaining to other people.........😏

 

"The pump and the whole heater is switched via the thermostat switch" - not strictly true - not on mine at least. Your upright unit has its own power supply which includes powering the igniter which, in turn depends upon the microswitch (or, in my case, a manual switch). So, you can turn the heater on to heat the water but, without the pump, only the water in the unit will be heated - not good!!  I have a room stat remote from the Alde itself. Once the boiler is ignited and the water temperature is set via the black knob I have to go to the room stat. That has a temperature setting and a switch. The switch turns on power to the pump in the top of the boiler / in the header tank. But the pump will only work if the stat is turned up above room temperature. A bit like your system at home (??) Set the room stat at the desired temp. The pump will work until the set room temp is reached then stop pumping. Temp within boiler unit rises because no demand for water being pumped until boiler thermostat turns gas off. Room temp drops - pump switches on - hot water pumped out of boiler - replaced by cool - boiler stat kicks in - boiler relights. Repeat ad nauseam.

Thus a common complaint with Alde Comfort - it doesn't work. Pump does not come on. Step one - check the temperature set on the room stat. If it is set low it thinks the pump is not required to pump hot water around the heating system. Pump will only work once Winter comes around.

So does your room stat include a switch. If 'yes' switch that on once the boiler is working but set the temp pretty high - I always use the max cos my 'heating system' is useless.

I agree with your sequence for the 2928 - one hand IF your microswitch is operating to spec - mine doesn't. So one hand for the knob and one for my jumper switch which bypasses the microswitch.

If I read this right, you turn on at the room stat first before operating the ignition - had not thought of that or tried that. Nothing wrong with that sequence but my pump is a bit noisy so I prefer to light boiler unit in silence - listen for the whump!! - then turn the pump on via the switch in the room stat.

 

 

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My 2928 installed in accordance with the Alde diagrams and instructions use three wires between the boiler and thermostat. One is a positive from the batteries, one is the switched supply back to the boiler, and one is the thermostatic switched supply to the pump. It is true that the battery positive supply goes to the multiplug on the boiler, but that is only used as a bus bar as far as can see.

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Hmm!! My system is configured as I inherited it so don't shoot the messenger! Sounds like you have to switch power to the boiler only via the room stat with switch ON and thermostat saying TOO LOW ie power the boiler and light the gas (presuming the pilot is already lit). If only at startup you still have to power from the room stat end then go through the boiler/pilot light up sequence.

I've never compared my setup to the 'official' wiring diagram - sounds like it is set up in a non-standard config. As previously, I can light the boiler/pilot then main burner with the switch on the room stat off (although the thermostat will always be set high). Then start the pump using the switch on the (remote) room stat. It still cycles on/off normally although it is only hot water that I am after.

The OP is getting continual sparking. I'm guessing regardless of the position of the control knob or room stat. So, as has been suggested, the microswitch is faulty or out of adjustment. With the control knob OFF the cam on the microswitch should surely pop out (switch off power to the sparky thingy) so it is stuck in or blocked in in some way.

Sounds like step 1 is to examine the microswitch.

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20 minutes ago, Opener said:

Hmm!! My system is configured as I inherited it so don't shoot the messenger! Sounds like you have to switch power to the boiler only via the room stat with switch ON and thermostat saying TOO LOW ie power the boiler and light the gas (presuming the pilot is already lit). If only at startup you still have to power from the room stat end then go through the boiler/pilot light up sequence.

I've never compared my setup to the 'official' wiring diagram - sounds like it is set up in a non-standard config. As previously, I can light the boiler/pilot then main burner with the switch on the room stat off (although the thermostat will always be set high). Then start the pump using the switch on the (remote) room stat. It still cycles on/off normally although it is only hot water that I am after.

The OP is getting continual sparking. I'm guessing regardless of the position of the control knob or room stat. So, as has been suggested, the microswitch is faulty or out of adjustment. With the control knob OFF the cam on the microswitch should surely pop out (switch off power to the sparky thingy) so it is stuck in or blocked in in some way.

Sounds like step 1 is to examine the microswitch.

 

True re the micro switch, but I think the knob turns the micro switch OFF when set to the off position and on in all other positions. As said earlier in the topic, the igniter in some way detects when the spark gap is in the flame and the turns itself off until the flame fails. Then is sparks again.

 

A misshaped or small pilot flame is known to cause constant sparking, as is a faulty igniter, so as long as it sparks when the nob is in any position but off  and it stops sparking when it is off we can conclude the microswitch is working.

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12 minutes ago, Tony Brooks said:

 

True re the micro switch, but I think the knob turns the micro switch OFF when set to the off position and on in all other positions. As said earlier in the topic, the igniter in some way detects when the spark gap is in the flame and the turns itself off until the flame fails. Then is sparks again.

 

A misshaped or small pilot flame is known to cause constant sparking, as is a faulty igniter, so as long as it sparks when the nob is in any position but off  and it stops sparking when it is off we can conclude the microswitch is working.

 

It relies on the ionisation in the flame to stop the spark.

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  • 1 month later...

Thanks all, finally got back to the boat and inspected the Alde, it appeared that there was something missing between the control knob cam and the micro switch. I guess some sort of lever. The control knob cam never gets anywhere close to the micro switch, have worked around that, have now installed a momentary push switch on the outside, so press the control knob for gas and the new switch to ignite.

 

Next issue, and I might be answering my own question…..

 

I cannot get the Alde pilot light to ignite. The boiler hasn’t been lit for about 2 years due to boat refit. But…….

There is currently no water in the system, radiators need reconnecting. I was only trying to light the pilot briefly as a test.
is there a pressure switch or something in the boiler, as in ‘no water in system therefore no gas is coming through’ or could there be another issue?

 

I would like to prove the system works, but will when all connected and ready be arranging a boiler service any way. 
 

Thanks again.

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No pressure switches.

 

The pilot assembly is probably fluffed up and damp. The flue tube has a habit of rusting badly and the rubbish drops into the burner and pilot. Cleaned out it will likely work but do make sure that the tube and flue have not rotted out.

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38 minutes ago, Nemysys said:

I was only trying to light the pilot briefly as a test.
is there a pressure switch or something in the boiler, as in ‘no water in system therefore no gas is coming through’ or could there be another issue?

 

This is a common problem with boilers which have a pilot flame, generally. When the boiler is left unused for a month or more, the gas inside the pilot tube percolates away into the atmosphere and gets replaced with fresh air. You may have to hold the gas valve button down for a couple of minutes or so to re-fill the pilot tube with gas before you can re-light the flame.

 

That's provided the pilot jet hasn't self-clogged itself with crud as Tracy suggests above. 

 

Edit to add: 

Something similar sometimes happens to the whole gas pipe back to the regulator in systems left unused for months. The whole system fills itself with air. Do you have a hob in the boat? Does that light first go if you try it? Or is that full of air too? 

Edited by MtB
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Thanks for the replies. Only have the Alde and a gas hob on board, both near each other and the gas bottles. Hob lights, have to purge the air first of course, both are running from the same gas pipe, Alde first then the hob. So have purged all the air apart from where the Alde tee’s off the main pipe. That’s not going to be a long tee pipe, probably <50cm. Always had to purge air for a short while, but this is extra long. 
 

Sounds like it could then be fluffed up or damp. It’s in such an inaccessible place. Is it something I can safely look at, or is it a ‘professional’ job?

 

I have gas detector alarm and CO alarm of course, but wouldn’t want to do anything dangerous. 

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The Alde that came with Belfast was very temperamental to light. The previous owner showed me how he addressed the problem by unscrewing the viewing window glass, then wiping the jet with a pipe cleaner soaked in WD40. It sort of worked but was a real faff. I ended up removing the whole burner assembly (about a million self tappers on the front to undo), having disconnected the gas supply pipe outside the casing. And of course to actually get the burner/front plate assembly completely out I had to cut out a bit of the wardrobe it was housed in. But it did give me the opportunity to clean the whole thing properly. And afterwards it lit like a dream.

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