Hi Max,

I understand that not all HXs are equal, but I don't understand why you're saying that at 1bar you machine is no good for one/two shots? Is it too hot? not stable enough? If it's a HX it should be reasonably stable after a cooling flush and during actual extraction. I know that the group on the S26s is pretty similar to the one on the Silvia, but still with the whole thing properly heated up it should be possible to pour a decent shot without having to drop the pressure to 0.5bar. I currently own an Elektra and it can get bloody hot after sitting for 45min. Think 105*C or sometimes higher, but that's normal and you have to flush to get to a reasonable temperature range.

I'm not saying here that you don't know how to use a HX (I'm sure you know best how your machine behaves), but I'm simply curious why you would want to run the machine in conditions which are against it's nature (low boiler pressure) and than make up for it by modifying the machine?

Regards,
dsc.

Thanks for the additional tips, Ian. Why a relay?

Tom, all comments are welcome, and appreciated too . Yeah, at 1 bar it's both too hot and unstable. With no thermosyphon and a small hanging group, the difference between the group and boiler temps is huge. Multiple group-warming flushes, followed by a HX cooling flush, or three, doesn't cut it. Even with such a procedure, the brew temp (measured with a TC under the shower screen) varies by as much as 10F from start to finish of shot (@1.1 bar or so). At 0.5 bar the dynamic is completely different, I still need to warm the group (a tiny bit) but after a quick flush the brew temp is almost constant.

I can't think of something easier, or cheaper, to implement. A 2-point PID would be ideal; but requires a PID, an SSR, a TC and a new hole in the boiler....my "oomph paddle" sounds very attractive in comparison

A relay to have very short thick wires to the element. If you have a 10 foot cord to a foot switch, you have 20 feet of additional wire dropping voltage to the element.

In a situation like this I would use a multiple pole relay with contacts rated at double the maximum CONTINUOUS current. Paralleling 2 or more sets of contacts gives you a robust, low resistance solution.