I am building an espresso machine using a La Pavoni Europiccola group. I have a 1.5 liter copper tank, 97 mm (c. 4 inches) in diameter. I am fitting it with a PID, probably from Auberins, and a frame welded up not unlike that of an Olympia Cremina. While there are a number of easy to install boiler elements to use such as the Microcasa, Starbucks Barista, Venus, or Domobar SUPER (I saw these at espressocare's web site), I haven't found any reports on watt density ratings and reliability. I suppose some brands are better than others. Or perhaps not.

Does anyone have such ratings or personal experience on the reliability and continued availability of elements?
I am not much interested in using a hot water heater element because of their length and size. I would like to keep the element in the bottom third (or lower) of the c. 20 cm tall tank.

Thanks for the warning. (All joints and materials exceed engineering standards for pressure tanks, including pressure release valve.)

It will be a thermo-siphon mostly identical to the Gaggia Factory.

1.5 L boiler, a cylinder 10cm across, guessing vertical orientation so you are looking at just under 20cm tall.

Figure that you will never go more than 70% full or lower than 30% on the water level in the boiler.

At the lowest water level you would have just over 6cm of water in the boiler.

You are going to need a short stubby coiled heater to keep the element from melting itself down.

Also figure in that range your water volume that is usable will be about 600ml. A double shot will be about 30-40ml. Flushing shots may be about 20-30ml. So lets call a pull of the lever about 30ml. That means shutting down, and filling up every 20 pulls of the handle. Or you could add some type of filling system.

Does that sound about like what you are looking at?

Thanks for the read! Finding acceptable tube stock wasn't easy. So I am trying to go with what I have been able to get (a free 'drop' as a sample, as it were, from a copper tube manufacturer!). Twenty pulls would be enough as there are just two of us - four for the occasional dinner party and cappuccinos.

I can make the boiler taller. The length of tubing I have is 30 cm. As to the height of the element, it sounds like you suggest that it might be better to have more residual water left in the boiler, ie, below the bottom of the sight glass, to avoid over-heating a partially exposed element. The only restriction, given I have enough tubing, is aesthetic, ie, how a tall machine would look. Maybe a Leaning Tower of Pisa motif? I could go to a 2 liter tank, I suppose.

As to a filling system, I like the idea, but haven't looked into the one way pressure valve requirements yet.

Any idea how the change from 1.5L to 2.0L might change the element wattage requirements?

I appreciate your interest and suggestions.

cas99 wrote:I can make the boiler taller. The length of tubing I have is 30 cm. As to the height of the element, it sounds like you suggest that it might be better to have more residual water left in the boiler, ie, below the bottom of the sight glass, to avoid over-heating a partially exposed element. The only restriction, given I have enough tubing, is aesthetic, ie, how a tall machine would look. Maybe a Leaning Tower of Pisa motif? I could go to a 2 liter tank, I suppose.

The big factor in changing the height is where you will bolt up the head and handle. If you scale up the boiler and then lift the height of the group you will front balance the machine more. Therefore you will need a bigger footprint and weight on the base to counteract the torque forward from the group handle. Since the volume is adjusted by the V=2ЛR²H rule then if you wish to have a shorter boiler then the R² property is where you want to adjust.

And yes more residual water in the bottom will save your element, but even then a second cutout temp sensor there would be wise. Also remember the greater volume of water you have superheated under pressure the better your steam time/volume will be with a given element wattage. But it will also take longer to recover with a smaller heater. In this size I would suggest you go and talk with the OE people and find out what sizes of coiled heaters they have in the 800-1000W range.

-Cecil

Thanks Cecil for the info. I do need to take into consideration the leverage problem. The 4" diameter tubing was free. I may have to extend the machine's base out a bit in front to compensate for the height.
I have found there are any number of elements available in the 800-1200 watt range available through espressoparts and espressocare, etc. that aren't too tall. i am looking at the microcasa element; and the SAECO element. Anyone know how tall they are?
I have available a Europiccola element, but it would be more cumbersome to machine a plate to attach it to the tube's bottom compared to those that require only 2 holes and gaskets.

Info is appreciated!

There may be one thing just as important as the element itself. You will need to check on the insulator and fittings for sealing the heater into the base of your boiler.

There is no point in specifying a heater element that will not have the support hardware readily on hand. There are a lot of older elements that you would have a hard time installing just because the mounting hardware is just plain hard to get.

So when you look at this try on ordering the element and the mounting hardware as a set. And if you need to repair it in the future the more common the installation set is the better chance you will have of doing a rebuild.

Is there such a thing as to big of a heating element for a volume?

-Cecil