Russell Hobbs Ceramic Coffee Percolator c. 1975

[Nick Odell]

I know, nothing seems to last any more, does it?

This percolator (Model CP2) stopped working yesterday and I have traced the fault to the thermal cutout which seems to have stuck in the cut-out mode. The markings on the device are 430-671 STEMCO L205 but the maker and part number are so ancient that I don't even get a Googlewhack so could anybody suggest a modern day replacement? This one is about 18mm diameter although since it is clipped to a flat surface anything about that size will do. I'm guessing that the temperature at which it switches off will be around 90-95deg C since it's a coffee percolator not a kettle but any advice about a suitable replacement would be gratefully received.

Many thanks,

Nick

[Theo]

Hard to say without a picture, but does anything here look like it fits the bill:

You'll probably have to filter by temperature.

Is it being used to switch mains directly or as part of a circuit? Many of those aren't mains rated.

There is also:

of which look more mains friendly.

Theo

[Matthias Czech]

Am 15.03.2024 um 15:20 schrieb Nick Odell:

18mm? Hm. Search for 'ksd 301' resp. 'ksd301' Does it look anway near that? If size and shape fit, choose one with the correct

-Voltage

-Amperage

-Switching Temperature

-Switching mode: Normally on vs. Normally on

They are cheap, approx. 1Pound + shipping Even available on Amazon (but more expensive there)

[The Nomad]

Nick

I found this ...

Wrong temp but ...

Avpx

p.s. 'ow's tricks?

[Matthias Czech]

Am 15.03.2024 um 16:36 schrieb Matthias Czech:

Normally on vs. Normally off. Sorry.

[mm0fmf]

There's a 1975 CP2 on eBay for £30 if you want to buy it for spares.

[Rod Speed]

Nick Odell [e-mail]> wrote

My stainless steel cutlery and stainless other stuff does.

[Nick Odell]

Yes, that's the type of thing - thanks.

Thinking about it, I wonder if the cut-off temperate might be rather lower than 90? There are two heating coils at the base of the jug, one which goes through the cut off switch and one that doesn't so I presume one is the equivalent of the hotplate on a filter machine and the other is the main heater. So if the cut off temperature were to be about 90deg, every time the stored coffee droped below 90 the main heater would kick in, wouldn't it? But if the thermostat were to be set lower then the steady temperature of the stored coffee would be maintained by the second coil. The trick must be to know what is the optimum switch-off temperature which allows the coffee to brew but doesn't keep switching on the main heater when the coffee is waiting in the pot. I have no idea what that optimum temperature should be - any ideas?

Nick

[Nick Odell]

Yes, I saw that too. I'm very tempted because it looks nicer than mine which is just a plain colour ceramic jug. But I already have too much coffee-making equipment both ancient and modern. And while I hate to throw things away, I don't want to hang on to broken and unusable stuff.

Nick

[Tim+]

My parents had one. Made horrible coffee. Is it worth preserving? They must have all disappeared for a reason….

Tim

[Nick Odell]

Correlation is not necessarily causation :-)

IMO the coffee I make/made in it is no worse than that I make in my filter > jug coffee maker though the simple camping cloth filter-on-a-ring probably beats both of them but a)requires human attention during the process and b)is messier to clean up afterwards.

For something nicer I can choose one of two different types of espresso maker or a French press but what I choose to use depends on the mood I'm in and which variety of coffee I have or haven't run out of.

Superceded by flashier kitchen gadgets, I suppose. If I can cheaply and easily make it work again it's worth it to me.

Any thoughts about the temperature setting for the thermal cut out? Does anybody know what temperatures are set by other, more modern coffee makers?

Nick

[Tim+]

I can’t see how it can function unless it gets up to at least the boiling point of water but I could be wrong. I suspect the thermal cut out is just there in case it boils dry or gets turned on with no water in it, in which case a replacement that works at 150°C should probably be safe enough. This might be bollocks though. ;-)

You could always try putting the “guts” of the percolator into a pan of water on your stove and see what temperature it needs to achieve to start bubbling over.

Tim

[Nick Odell]

I think it's down to the relative positions of the two heating coils and of the thermal cutout. I think one heater is there to keep the coffee warm and works like the hotplate on filter machines; the other is a more powerful heater, closer to the centre, and the water at the base of the stem is made to boil and the steam created by this action forces increasingly warmer water up through the tube and down through the grounds until the whole reservoir of water reaches a temperature that switches the main coil off. Having released the old thermal cutout, I can see that it's not fixed directly to the hot metal parts but to a thin, springy metal tab which IS attached to the hot metal parts. So there's a temperature gradient between the mass of the heater and the sensor.

It's a very clever and carefully engineered piece of kit which brings me back to your earlier point about why they stopped making it? Perhaps because it needed to be carefully engineered and the trend has been towards mass production by less skilled or unskilled workers.

It reminds me of the Sunbeam Radiant Control Toaster which has no timers and no levers but - thanks to clever application of science and engineering - lowers the bread into the machine by itself, produces toast regardless of the size, shape or starting temperature of that bread and raises the toast up again when it's done. Some have said that it was the perfect toaster but they stopped making it years ago. There's no way you could build that with unskilled labour nowadays - although with robots and AI, maybe they actually could? I wonder???

Nick

[Thomas Prufer]

Okay, since you had no luck on searching for the part number...

I had no luck in a quick search of spare parts for other percolators - I'd hoped to get a temp spec form on of those, assuming the temp is a function of water and coffee and not the specific model. (My percolator has a spirit lamp, and makes fascinating coffee that tasted pretty bad.)

Is the part borked, or can it be unstuck for one last drop into hot water, to see at which temperature it clicks?

Would you be comfortable bridging it, percolating, and then seeing at which temperature you'd say "okay, this is hotter than it's ever, been, it's shouldn't be spewing a geyser of coffee", and reading off the liquid temp and going a bit lower?

Or maybe assume "205" is 205 °F which 96.1 °C -- which seems a little high if it's there to stop the coffee being percolated. (Water boils at a lower temperature in some leftpondian mountain states; possibly irrelevant to a UK percolator...) And the stick in an 85 °C model and see what happens. A KSD 301 is about 0,7 Euros here, not a big loss if too low a temp.

Thomas Prufer

[alan_m]

It all depends by what you mean by unskilled. The assembly worker may not have the skill to design the item nor have the skill to design the engineer process to manufacture individual parts. He only needs the skill to assemble that item, and often only a small part of the final product.

Probably before the time of Henry Ford and his production lines "unskilled" workers have been used to mass produce fairly sophisticated consumer items.

[The Natural Philosopher]

The rise in mass media has led to the phenomenon of spending all the money on marketing, and none whatsoever on the actual product.

Unskilled labour today means a robot. Or china.

[Nick Odell]

I've knocked it about a bit but I can't persuade its contacts to close again

I think we are heading along the same track here: although I had earlier bypassed the thermostat just to check that the heater coil was working I thought that the holding temperature of the coffee is probably key to the operation so I filled the jug with hot water, plugged it in so that the warming coil could do its stuff on its own and waited for the temperature to normalise. Which, according to my temperature probe, happened at just under 70°C. A quick dash to empty the jug and measure the temperature on the thermostat tag and that came in at just under 65°C.

From the data sheets I've unearthed from different makers of the KSD

301 types, the reset temperature is typically 10-15°C lower than the opening temperature so I'm thinking something with an opening temperature of around 70°C ought to do it. But since they are so cheap, I'm going to buy one higher and one lower, just in case.

Thanks

Nick

[Tim+]

I still don’t see how it’s ever gonna percolate if it doesn’t go up to boiling point. If the stat opens at anything less than 100°C you’re gonna be watching a percolator full of warm water forever.

Tim

[Sam Plusnet]

Not consumer items, but the Royal Navy and the manufacture of pulley blocks is the usual example.

[alan_m]

The boiling water only needs to be localised at the bottom of the central tube. This boiling water immediately travels up the tube into the coffee grounds. It then filters back to gradually warm the bulk of the water. By the time the average temperature of this bulk has reached, say, 70C enough boiling water has travelled up the narrow central tube to brew the coffee.