Hi Folks:

I'm a new member of the Caravel club. Just got this first version (1.0) when they started the Caravel brand but with a lot of the VAM features and build quality. I've browsed lots of old threads and am trying to achieve easy temperature control. I'm running this 220V machine on 110V, having changed out the plug for a U.S. outlet. (I'm planning to have an electrician install a 220v outlet at the end of next week to accommodate European machines like this.) I followed a tip to start with 1/2 inch water in the tank, turn the heater on and let that heat the machine for several minutes and then fill the tank with boiling water to pull a shot. People who have succeeded with that setup have the TSTAT (mechanical temperature switch) running within a nice range, but I've been not so lucky with that. First here's a beauty shot. Vintage drip tray and grate are in transit and I'm getting the Orphan Espresso replacement portafilter handle as a stopgap until I can find an authentic looking handle to complete the restoration. First a beauty shot:



And VAM branding still on the case:



And the shot that's most important, the espresso, is excellent. But now for temperature control. I'm thinking of going to a PID and here's why. As it was the machine wouldn't heat past 79C when the target is 90C. I've read that people have "bent the bar" that helps the TSTAT sense expansion on the boiler to get the TSTAT within range. Here are the relevant parts. The back of the boiler has a bar welded onto it that apparently expands with heat.



It then touches the black tab in the middle of this assembly, which opens the circuit on a microswitch that activates the heating element. If the black switch lever is too close to the bar on the tank, the TSTAT cuts off before the water is fully heated. There's another catch here -- the catch that holds the boiler in place. The button sticking out on the back of the boiler catches the fixture above the switch lever to lock in the boiler, which brings me to part of my problem here.



Looking at the back of the machine, the upper button activates or releases the catch. I've figured out that the lower button turns clockwise to move the TSTAT higher and when pressed it clicks the power on. If the machine is unplugged, plugging it in activates the power.



I've tried bending the part that connects with the upper button so it holds the boiler a touch further away, but I'm still not getting the TSTAT within range and it's now harder to lock the boiler into the case. After two hours of fiddling with this I've just about had it and am thinking that PID is probably the way to go, unless someone can chime in and tell me an easy fix to get the TSTAT within a workable range.

I understand that to connect a PID (proportional integral derivative temperature controller) involves bypassing the TSTAT and using the PID as a control. A PID requires a SSR (solid state relay). I see that this is a commodity device listed on eBay where a PID with SSR and K-type thermocouple can be had for about $20 shipped from China. The typical unit at this price is a Rex C100FK02 PID with the other components, like this:



The specs listed with this unit say it will work on 100v to 240v input. In another thread, TitoM offered a circuit diagram for installing an Auberins PID.



The Auberins units are much more expensive and appear to be repackaged ones like what I see on eBay. I'm thinking of getting the eBay device and connecting it. But I don't know which PID outputs I connect to which SSR inputs and how to wire this up. Yes, I can ask the seller, but what questions should I ask? I'm assuming the PID will train itself using its internal fuzzy logic.

As an afterword, I'm glad I disassembled the three prong Italian plug that came on my Caravel. When taking it apart I discovered that the yahoo who wired it up disabled the grounding cord! This despite the power cord being wired up with ground. I clipped off the end of the power cord and retrieved all three wires to attach an appropriate adaptor. It's worth checking these things rather than just inserting the Italian plug into an adaptor.

Rick:

Can you please show us that kettle controller and how to find one? I read about it in the other thread but when I search for "kettle controller" or "kettle PID" I come up with a variety of confusing items and nothing affordable that's obviously the right thing.

Thanks, guys. I did adjust it both ways to make sure and on my machine clockwise makes it hotter.

Tomorrow morning I'm going to get together with yakster who is kindly lending me the PID controller he uses for his La Peppina. He has another control box for me too. I'll check that out and then see if I want to order the components I showed in the first post. I think setting a PID will be more convenient than a dimmer since I'll need to bypass the TSTAT anyway.

@ Julian: Good idea to push the TSTAT up so you can stay with original wiring. Somehow I can't get it that hot since the mechanical pieces I have couldn't be bent into place.

Hey Gary,

Congrats on your new Caravel. She is a beaut. I am really looking forward to hearing about how you like the shots, especially compared to your other beauts.

I think the PID solution is a good one. But I can't help but think that it would be nice to have the thermostat working as it should. Part of the marvel of this particular machine is the simple elegance and functionality of the mechanical thermostat. My deadband is about 7-9 degrees F, which isn't PID-worthy, but works for me. Jack Peacecup was touting a 2-3 degree deadband, which is phenomenal.

I had another thought of something that you can investigate on yours. Jack (sorrentinacoffee) helped me with another issue that I think may be something to look at. The mechanical thermostat relies on the boiler sitting in exactly the right position as one variable in the system working correctly. The other variables are the things you tried to adjust - the tab on the back of the boiler and messing with the thermostat controls and lever system that press in the switch.

So the spring/element positioning system (SEPS) that Jack is talking about on page 89 of the Caravel thread is key to the boiler making maximum contact with the element and also the boiler being in the optimal position for the thermostat to work correctly. In my case, I had one original spring that was toast and a replacement spring that looked like it was from a Bic pen (pronounced "beek" in Italian). So I went to my local hardware store and bought a couple of springs that were approximately the same size and slightly thicker than the original - just by eyeballing. They work great. The boiler really locks in tightly and the thermostat has become completely reliable and predictable.

One other thing about the SEPS; the place where the tray clips into the thermostat on/off lever needs to be in the right spot, I believe. Assuming yours is the same as mine - there is a grommet-looking thing at the top of the spring on the lever system. You push down the grommet and clip the tray in on top of it.

Hope that helps and I hope Mr. Sorrentinacoffee chimes in with his wisdom on this.

Pete