I am sure you(Caravel owners) have seen this - the water bubbles forming in the shape of heating element inside kettle. Stainless steel kettle has its advantage of being non-toxic and keep the heat well once it's up to temp. However, it is also known for poor heat conductivity, so that's why the heat is focused where the element is touching the kettle.



Let me know what you think about this - Is it a good idea to sandwich an aluminium sheet between the heating element and the kettle? I've done this with aluminium foil(layers of them pressed together) for a few session and it does distribute the heat better. However, I am not sure if that's going to have unwanted effect in the long run, eg corosion or other unknown effect. I am not sure too what material is the heating element made of, but aluminium seems to be quite low on the anodic index http://en.wikipedia.org/wiki/Galvanic_corrosion. If anything, it's more likely that the aluminium will corrode itself and protect the heating element. Is that the right way?

The main purpose of this exercise is to protect/prolong the element. My Caravel(soon to a new owner) is working perfectly, but I just want to do my best protecting this vintage - prevention is better than cure! I supposed some of the older Caravels are prone to damaged heating element is due to this reason (the heater is too hot itself because heat is transferred insufficiently to the kettle).

Will this work? Or am I overthinking it?

Glad to hear the aluminum foil works! I've been considering a copper sheet (though aluminum might be wiser!) with a thermally conductive pad on the side facing the boiler. I have the pad already, but I haven't played with the copper yet :/

Hi Will,
Please do try the copper sheet out, glad to know you've been thinking the same also! I've used aluminium only because it's the easiest thing to find in a kitchen, nothing more than that. It does give off some odor the first burn in, but after that it does just fine.

Prior to the aluminium foil, if I remove the kettle (plugged off of course) 20 seconds immediately after the water is boiling, I can see some red spot on the element (particularly in the front center). Now I don't. So I guess & hope this is doing some good and not bad to the element.

Got my doubts. Yes aluminum or copper are good conductors of heat but by placing a sheet between the element and the tank you may in fact slow down heating which means the element may stay on longer and remain hotter than normal. I guess you could try it and time it. If the thermostat cuts in more quickly then the modification has worked and the element is doing less work.

I would approach the idea of conserving the element from a different perspective. I think introducing bits of aluminium foil etc is more likely to cause a problem especially if a piece got torn off and fell across a live terminal.
The first point is that a Caravel heats up reasonably quickly, (assuming similar times across the pond on 110VAC), so I do not consider it to be a machine that needs to be left on all day and as such the element does not need to be left cycling on / off for hours on end. Turn it on when you want to use it and maybe leave it on for a shot or two in the short term but after that shut it down.
In order to reduce the time the element is on pre boil your water and then fill the Caravel from your boiling jug. If you do that the element is only heating up the water a few degrees. When I load the boiling water into a cold Caravel it may drop to the low 90's but then the element is only on long enough to heat up an additonal 2-5 Degrees. I could go and fire it up to get more precise numbers but you get the general idea.

Seacoffee wrote:Got my doubts. Yes aluminum or copper are good conductors of heat but by placing a sheet between the element and the tank you may in fact slow down heating which means the element may stay on longer and remain hotter than normal. I guess you could try it and time it. If the thermostat cuts in more quickly then the modification has worked and the element is doing less work.

That's a great idea there! I will test it out and report back after the weekend.

Beanz wrote:I would approach the idea of conserving the element from a different perspective. I think introducing bits of aluminium foil etc is more likely to cause a problem especially if a piece got torn off and fell across a live terminal.

You have a point there but if the thermal distributor idea works, definitely it's better to use a sheet instead of foil. The foil was just for testing the idea.

Beanz wrote:The first point is that a Caravel heats up reasonably quickly, (assuming similar times across the pond on 110VAC), so I do not consider it to be a machine that needs to be left on all day and as such the element does not need to be left cycling on / off for hours on end. Turn it on when you want to use it and maybe leave it on for a shot or two in the short term but after that shut it down.

Yuppies, for me room temp to boiling is about <10min with 3/4 kettle. And that's exactly what I do. I take care of my machine like my baby so I don't really leave them on for more than 5 minute - except for the first heat up. May be some of the Caravels that have burnt out heating elements were due to being left on boiling for extended period?

Preboil idea sounds reasonable but may be a little over the top for the lazy me. Too many steps - I need to buy a reasonable-sized kettle, cook it on stove, wait, pour, turn on the machine, wait.

Seacoffee wrote:Got my doubts. Yes aluminum or copper are good conductors of heat but by placing a sheet between the element and the tank you may in fact slow down heating which means the element may stay on longer and remain hotter than normal.

The reason I was thinking about this was for a replacement for the element. On my VAM, I get up to temp in about 15 min with a "full" boiler. On a Caravel 1.1, it takes almost 25 min (yay 110v). I'm gifting the 1.1 and I had wanted to upgrade it to work more quickly before I sent it off, and I was thinking about using a cartridge heater or something similar (but I lack CNC capabilities , so I was looking at how I could encourage thermal transfer (a la a CPU heat sink).

Seacoffee wrote: If the thermostat cuts in more quickly then the modification has worked and the element is doing less work.

I'll see if the heat-up time on the 1.1 is faster once I trim my spare copper to size!

Slight tangent:

In response about heat-up times, I recently acquired a 220v VAM that I operate on a step-up transformer and already have a VAM with a replacement 110v element. I was curious to see if one was quicker than another. The 220v goes from room temp to basically boiling slightly faster. The difference is about a minute. But the total time is about 13-14 minutes for each. I will time it because I am going by memory from a while ago when I timed the 110v.

Pete

Just for the record, in case I forgot it With the aluminium on, heating from 29 Celsius to 100 Celsius (Boiling) took roughly 8:30 for 600g (weighted) of water. Will do this again tomorrow without the foil on.

Alright. I have removed the foil and heated up another 600g of filtered water. Without the foil, the time from room temp (around 29 Celsius) to boiling was..............................*drum rolling* 8:55 minutes

So, either the foil has resulted in 30 seconds quicker boiling, or it's just the fluctuation in the ambient temperature. Regardless, it isn't as significant as I thought. Weighing against the possible unknown long-term effect, it's probably better to do without the foil and let the stock Caravel does its magic, just like Julian has suggested.