Pstat dead band is about 1.15 to 1.35 bar. I think I'd like to install a PID eventually, mostly so I can have a timer to lower boiler temp at night and raise it in the day. I'm not sure how to get a temp probe into the boiler, but I would guess a temp probe on the outside of the boiler will read close enough to the internal temp. I measured the external temp at 222F when the boiler pressure gauge read 1.3 bar, and the boiling point of water at 1.3 bar is 225F. My understanding is that with a HX machine, precisely controlling the boiler temp during operation isn't that critical?

I still think the brew water seems not hot enough. When pulling a shot with no portafilter, the water isn't flash steaming or anything similar. I'm curious how best to measure brew temperature, beyond sticking my instant read thermometer into the portafilter spout. Maybe a probe into the group connected to a display mounted somewhere not too unsightly?

I did pull a few experimental shots but - don't laugh - I don't have a tamper so it was hard to prepare the coffee in the basket. Anyway, the shots were drinkable. Better, to my taste, than I often get at cafes. I have lots of experimentation ahead. Random beans, but freshly ground. The shots seemed a little lukewarm. One had about 1/4" of crema.

Looking into the PID idea more. I'm reading about $100 SSRs failing in the "closed" position prematurely due to heat and moisture. I'm thinking about simply using a $18 "normally open" relay from the autoparts store. Auto components are designed to operate in hot/wet environments and the standard parts are cheap.

A standard pressurestat set slightly higher than the PID inline with the SSR should remove all the concerns about the SSR failing. A mechanical relay connected to a PID will likely fail in very short time because of the constant cycling the PID will cause.

Ira

Thank you, ira.

One quick Q - what's the best way to test that auto-fill is working? Is there supposed to be voltage at the lead that connects to the water level probe?

I don't think there is anything at the probe you can measure without an oscilloscope. Usually you test them by pulling the wire from the probe to make sure the pump turns on and shorting it and making sure the pump turns off. I'm sure there are better ways, but I've never come across a bad one so I've never had to pull out the oscilloscope to see how it works.

Ira

jyl wrote:Looking into the PID idea more. I'm reading about $100 SSRs failing in the "closed" position prematurely due to heat and moisture. I'm thinking about simply using a $18 "normally open" relay from the autoparts store. Auto components are designed to operate in hot/wet environments and the standard parts are cheap.

Using an automotive relay may work but automotive relays operate with a 12 volt coil and may not have contacts able to carry the load you need. Relays are rated by the maximum voltage and current they can handle. There are plenty of choices for good 110 volt relays on eBay or buy new on Mouser Electronics or similar. However, an SSR is a much better choice. There are no contacts to wear out. A good SSR can switch a heavy load when the AC voltage crosses zero putting much less stress on the circuit. If you close the contacts on a relay when the AC is at a peak you will get arcing and burning of the contacts over time. Not sure who told you SSR fail from their environment but I would doubt it. They do fail like all components but not very often. I don't recall having one fail closed. Mostly something just breaks and it quits switching. SSRs are pretty much the standard for heavy loads like motors and heaters. If you do use devices that can fail closed it is standard to include fusible links or thermal fuses to avoid a melt down. You can pick up Crydom SSR on ebay used for $20 to $30. They are plentiful and widely used for industrial applications.

Thank you. That all sounds pretty convincing. I had thought SSRs were more expensive.

Here is a video of the third shot pulled with this machine. http://www.youtube.com/watch?v=p89pNB0alFk

I have no idea what I'm doing wrt grind, tamping, doses, temps, etc but at least it seems like the machine is more or less functioning. The only new problem I've found is that the middle button on the left group keypad is not responding, but whatever . . .

Making progress. The Elektra has a new heating element and pstat, the steam valves are no longer leaking, it is fully functional. Well, I still need a new programming switch. Cosmetics - side panels, polishing - remain to be completed. The PID/SSR modification remains in the plans. Also a heating element safety switch is to be added. I'm still missing the hot water valve but, until a used one turns up, will operate without. Turning now to preparing the "coffee station" in the dining room.