# Gaggia Classic Thermofuse, no direction home.



## Norvin (Sep 10, 2014)

After blowing the thermo fuse on my Classic while setting up a PID, I replaced it with a spare from my box of bits. After fitting it and looking for a replacement for the spare I noticed that a lot of commercial sellers state that it is directional, and to take note of the orientation of the original and fit the replacement the same way.

Well guess who didn't.

Ok I'm not an electrical engineer but I can't see how it makes any difference, the power is a/c and cycles 50 per second. Other instructions that I have found on the web state to fit it any way round, so thats helpful.

What happens if you connect it the wrong way, does it simply not work - hard to see as I assume a heat sensitve part blows if overheated, or does it blow a hole in the space/time continuum?

Is this an instance of people blindly cutting and pasting instructions even though they are wrong and prepetuating a myth, or are there good reasons for fitting one way only?

If there are good reasons and it is directional, and believe it or not I'm not always right, can someone please check their Classic and let me know the correct way - there is a 50/50 chance that its Ok at the moment, but then there's also sod's law...


----------



## froggystyle (Oct 30, 2013)

Does checking my gaggia mean i have to strip it down?


----------



## Norvin (Sep 10, 2014)

Hi, thanks.

You just have to take the top warming plate off. The thermofuse is hiding in a clear plastic sheath clamped to the top of the boiler. It is cylindrical with a taper at one end. You may need to undo the philips screw holding the clamp to remove it to see the fuse.


----------



## froggystyle (Oct 30, 2013)

Ok, ill have a look after 6pm.

Ill post a pic.


----------



## hotmetal (Oct 31, 2013)

I can't think of any good reason why a thermal cutoff should be directional. They seem to usually have a 'pointy' design but I don't think it's significant. It's not a diode AFAIK, I would have thought it's just something that melts if the ambient temperature reaches a level beyond the cutoff value. It could also get hot due to excessive current. Oh, and soldering&#8230; so if it's soldered in, make sure you have a heat sink between the iron and the fuse body.


----------



## El carajillo (Mar 16, 2013)

Norvin , just checked there is no indication that the fuse is "directional", there are no markings on the fuse to indicate that it should go in a particular orientation and if it were required I am sure it would say /indicate. FWIW the tapered end sealing is connected to the single brow feed wire.


----------



## Norvin (Sep 10, 2014)

El carajillo said:


> FWIW the tapered end sealing is connected to the single brow feed wire.


Thats the way I fitted it! What a relief, I'll be able to sleep tonight.

If there's no difference, why do most commercial sellers say that it is directional?


----------



## El carajillo (Mar 16, 2013)

Norvin said:


> Thats the way I fitted it! What a relief, I'll be able to sleep tonight.
> 
> If there's no difference, why do most commercial sellers say that it is directional?


Possibly they do not know OR just B/ S


----------



## grumpydaddy (Oct 20, 2014)

I think of a thermal fuse as being a pair of contacts held together by a ball of material that melts at a given temperature. ball melts, no more tension holding contacts, no more circuit. I would not expect it to be polarity conscious however I would think it is important to mount in the same, north, south, east, west direction.

I guess this could be done in a semi conductor package if it were low voltage


----------



## 5am (Oct 16, 2018)

Stumbled upon this post whilst looking for similar issues with a sage coffee machine - I know this is an old thread but posting in case someone else does the same. [Is that ok, admins?]

FYI the orientation of the thermal fuse does not matter, these fuses are used with AC application so the direction of current is constantly changing anyway.


----------

