Gas Fire External Flue Pump - Can you identify?

[GadgetUK]

Hi, I have a magiglo gas fire that today started tripping the mains and blowing mains fuse each time it was switched on.

I believe I have traced the short to the exhaust fan outside the house, not sure what it's called but it's located in a metal shielded casing that fits on the exhaust part of the fire outside the back of the house.

The white sticker had a model number on it but it was really dirty and unreadable. I just 'touched' the area to remove the dirt and the ink just 'fell off'....

Please take a look and see if you can advise on what may be a suitable replacement:-

 

[giblets]

The picture shows a safety device which, I'm afraid, you will need an RGI to fix.

 

[ChrisR]

Yes, Corgi oiks know exactly what the part is, what it does, why it blows the fuse and what to do about it.
We also know that if you go in there not quite knowing what you're doing, you kill the people in the house, so I don'rt expect anyone will give you the answer so you can DIY. Or should that be DIE.
I expect the part is about £30.

Hope you don't find that an unreasonable answer!

 

[GadgetUK]

Yes, Corgi oiks know exactly what the part is, what it does, why it blows the fuse and what to do about it.
We also know that if you go in there not quite knowing what you're doing, you kill the people in the house, so I don'rt expect anyone will give you the answer so you can DIY. Or should that be DIE.
I expect the part is about £30.

Hope you don't find that an unreasonable answer!

That's fine and I very much appreciate the reply!! I at least now know it's not going to cost me £500+ for a new fire. I am an electronic engineer by trade and felt comfortable checking the electrical side of this out and tracing the short to this 'safety device'. EDIT: It's an air pressure switch, found reference to it in the service manual. I am speculating that the short is caused by a failed bridge inside, either bridge rectifier package or diodes forming a bridge.

I will call out a Corgi guy =) Thanks ever so much for the reply!

EDIT: Assuming it is the bridge, I wouldn't dream of trying to fix it since it's a safety device, it's not worth the risk as you already stated.

 

[WDIK]

Posted: Wed May 28, 2008 7:28 pm Post Subject:



--------------------------------------------------------------------------------

ChrisR wrote:
Yes, Corgi oiks know exactly what the part is, what it does, why it blows the fuse and what to do about it.
We also know that if you go in there not quite knowing what you're doing, you kill the people in the house, so I don'rt expect anyone will give you the answer so you can DIY. Or should that be DIE.
I expect the part is about £30.

Hope you don't find that an unreasonable answer!


That's fine and I very much appreciate the reply!! I at least now know it's not going to cost me £500+ for a new fire. I am an electronic engineer by trade and felt comfortable checking the electrical side of this out and tracing the short to this 'safety device'. EDIT: It's an air pressure switch, found reference to it in the service manual. I am speculating that the short is caused by a failed bridge inside, either bridge rectifier package or diodes forming a bridge.

I will call out a Corgi guy =) Thanks ever so much for the reply!

EDIT: Assuming it is the bridge, I wouldn't dream of trying to fix it since it's a safety device, it's not worth the risk as you already stated.

total spherical objects

 

[GadgetUK]

Posted: Wed May 28, 2008 7:28 pm Post Subject:



--------------------------------------------------------------------------------

ChrisR wrote:
Yes, Corgi oiks know exactly what the part is, what it does, why it blows the fuse and what to do about it.
We also know that if you go in there not quite knowing what you're doing, you kill the people in the house, so I don'rt expect anyone will give you the answer so you can DIY. Or should that be DIE.
I expect the part is about £30.

Hope you don't find that an unreasonable answer!


That's fine and I very much appreciate the reply!! I at least now know it's not going to cost me £500+ for a new fire. I am an electronic engineer by trade and felt comfortable checking the electrical side of this out and tracing the short to this 'safety device'. EDIT: It's an air pressure switch, found reference to it in the service manual. I am speculating that the short is caused by a failed bridge inside, either bridge rectifier package or diodes forming a bridge.

I will call out a Corgi guy =) Thanks ever so much for the reply!

EDIT: Assuming it is the bridge, I wouldn't dream of trying to fix it since it's a safety device, it's not worth the risk as you already stated.

total spherical objects

What???

 

[scatmanjohn]

Are you sure its that?

I have had one or two of them blowing the fuse.

It was that little gold coloured resitor than you can see in the corner of the picture.

I believe you have to buy the pcb and that part comes with it.(or was that a kinder fire..can't remember for sure) worth a check though.

 

[GadgetUK]

Are you sure its that?

I have had one or two of them blowing the fuse.

It was that little gold coloured resitor than you can see in the corner of the picture.

I believe you have to buy the pcb and that part comes with it.(or was that a kinder fire..can't remember for sure) worth a check though.

Thanks, will check the resistor again tomorrow, I think it measured 220ohm, but I didn't disconnect it to see what the can was marked underneath, if it is the resistor that would save me a load of hastle and money. The short measured across live and neutral, 0.35 ohms. When I disconnected 1 wire that came from the air pressure sensor to the neutral input the short vanished from the live and neutral feed, I also found the same with the relay or whatever it is that sits inbetween. ie. short over neutral and live when its connected, when the relay is disconnected the relay measures ok.

EDIT: What would help if someone could explain why it fails, is it a common fault, is it the bridge within the air presure switch? I know there's a lot of resistance for safey and legallity reasons, but I honestly don't intend on replacing this myself, I just want to understand what has happened and why. It's almost like the thought policy are heavily involved in anything Corgi related, and I find it very frustrating. I am sure there are loads of idiots out there who do try to fix their own problems and either blow themselves to kingdom come, or gas their entire family, but these kind of things can happen because people aren't forthcomign with information, ie. how it works, what goes wrong, what the actual risks are. I just read a post identical to this one on another forum, the idiot over there bypassed the sensor to get his heating working, because no one would explain what it did and why it failed - that's my point!

 

[Corgigrouch]

Forgive me if I'm wrong, but I can't see how it can be the air pressure switch, it only switches from normally closed to normally open, unless it is giving a dead short to the casing

Having said that I have had fun and games with air pressure switches in the past, one of which suggested that it was perfect when testing with my meter but would be quite intermittent.. I always carry an APS in my van that I use for testing by substitution

 

[GadgetUK]

Are you sure its that?

I have had one or two of them blowing the fuse.

It was that little gold coloured resitor than you can see in the corner of the picture.

I believe you have to buy the pcb and that part comes with it.(or was that a kinder fire..can't remember for sure) worth a check though.

Hi,

British Gas came out to check the fire today. The engineer thinks it's the resistor and has ordered one - although they aren't sure it's the right part and whether it's even available, which seems madness to me. It's just a 220ohm RS resistor, probably 2 watt or something.

Has anyone had experience with this resistor causing the mains to trip?? It still measures 220ohm, so unless it's leaking to the can and earth under load I cannot understand it... I get the distinct feeling the engineer will return on Friday and say it cannot be fixed.

 

[ChrisR]

The danger of working on tings like fans isn't the individual component, it's recognising that the part you knock with your elbow, or fail to notice altogether, is important.
Most of us can do a bit of cutting and sewing but having a go at neutering the dog might get us into trouble.
A doctor might just give you a pill and if private charge you a lot of dosh, but that's for the myriad other things he's considered.

etc.

The reason those nasty Dungs aps's blow fuses is because of the way they fail and the circuit they're in. They tend to get welds, water or whiskers between the NO and NC contacts inside.
This circuit snippet is from a lowish tech appliance with a Dungs aps. Look at what's connected to the NO and NC contacts of the "Pressure Switch".....
See???

View media item 1622

 

[scatmanjohn]

Can you get someone to switch it on whilst you stand outside and look at the resistor.

The ones i had were shorting on to the resistor body and could be seen arcing for a split second just as power was applied.

 

[ChrisR]

Maybe they get damp?

 

[GadgetUK]

Thanks for the good help and advice guys!

I just thought I would post the final update on the outcome. The British Gas guy came with the replacement resistor and fitted it, it solved the mains tripping but the fire still wouldn't light. The APS had some blockage, he cleared the blockage with a bit of air and all sorted.

I wouldn't have supsected a blockage in the APS and to be honest I believe there would have been a risk in me attempting to clear the blockage myself as I would have had to disconnect one of the tubes and there's always that possibility that it's not completely air tight.

It's a little frustrating that the resistor probably cost all of about £2 yet the bill was £168. I guess £168 is worth it knowing that the job was done properly and my family is not at risk from CO poisoning.

Going to get a CO detector as well as recommended by the engineer.

I found it interesting that the resistor measured 220 ohm as marked on the package / heatsink, I can only assume that it must have had a leak to the can and in turn to earth. I guess if I had tested for leakage to earth from either end of the resistor all would have become clear but I still wouldn't have been able to start the fire because the APS was blocked.

I don't think it's possible that the APS blockage had anything to do with the resistor fault, I suspect the APS became blocked just because the engineer was messing around checking all of the connections, fan rotation etc.

Thanks for the advice!!