Should I PID an HX E61?

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#1: Post by Napoli »

Hi everyone.
I know this has been extensively treated as I've read various posts on the forum, but still I can't find an univocal answer to my question.
I am the lucky owner of an original 60's Faema E61 beautifully restored by Enrico Maltoni with a modern pstat.
What will be the real benefit(s) of having a PID controller on a single boiler HX E61 machine?
Would it be worth the hassle and the cost?
The mods will be reversible anyway as I understand.
Thanks in advance.

Team HB

#2: Post by JRising »

There would really be no benefit to it, unless you're able to believe that it matters for steaming some particular milk or something.
It would definitely cost something, so my opinion is "No, it's not worth it", certainly not unless you're in need of replacing the pressostat at which time the pressostat will still be the more affordable solution.

Others' opinions may differ.
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#3: Post by homeburrero »

Congrats on that Faema E61. I've always wanted one, love the way they look, and am comfortable with driving an old school E61 HX.

The pStat on your machine will have perhaps a 0.2 bar deadband, which causes the steam boiler temp to fluctuate regularly over about a 3 ℃ range. But that little fluctuation is dampened by the water in the HX, thermosyphon, and the heavy brass group, so it functionally makes no difference in brew temperature.

Having a PID in a dual boiler with a saturated group is nice because you can easily dial in different brew temps. On an E-61 HX you don't normally fuss with different brew temps for different coffees, but when you want to do that you can do it via longer or shorter cooling flushes.

It's true that manufacturers like Rocket are now putting PIDs in their E61 HX machines but they have multiple reasons for doing so, involving marketability and maintenance issues . (People believe PIDs are better, PIDs and SSRs are probably more reliable than pressurestats, and having the same parts for their DB and their HX machines simplifies things.)
nínádiishʼnahgo gohwééh náshdlį́į́h
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#4: Post by Pressino »

Far more useful than a boiler PID on a HX e61 machine would be installing a thermometer in the "nose" aperture of the E61, which would allow you to measure the temperature of the brew water entering the group's brew chamber. The water temperature in the steam boiler is of no specific concern except as it regards steam pressure (as pointed out in the post above). The brew water comes from a tube that is heated by surrounding steam boiler water, which is going to be much higher than you want to brew espresso. That's why HX machines require an initial "cooling flush" just prior to extraction. Knowing the temperature of the brew water is much more important as regards how your esprersso turns out than knowing the temperature of the water in the steam boiler.

I'm not saying there is no benefit at all from installing a PID to monitor and control boiler temperature in an HX machine. I may help you minimize the need for cooling flushes, depending on how frequently you brew espressos.

Napoli (original poster)

#5: Post by Napoli (original poster) »

Thanks for the fast replies.
I highly appreciate your opinions
To homeburrero: just buy one.
They look stunning and make you feel like a locomotive machinist.
And are a good investment like classic cars and old Vespas

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#6: Post by cafeIKE »

A PID allows walk up shots w no flushing. Add a switch to engage the pstat when you need steam and it's a match made in heaven.
I used mine for about 15 years.

See HX Heaven or 1½ Boiler


#7: Post by Curt-HB »

Hi Napoli

Fun project. I have a VME HX. I got tired of dealing with the poor reliability of the pstat and looked into a pid conversion. In the end, decided to do the intermediate step of keeping the pstat and converting the circuit to low voltage with a SSR. Pstats often fail because of the high current beats up the switch contacts. Since switching over to SSR, reliability problem went away. Also, one can then focus on ideal pstat behavior rather then shopping pstat with sufficient amperage. Of course, the door is open to go PID in the future. If you choose to go pstat+ SSR, you'll need a convenient low voltage source. I found it easiest to use a usb cable run to mini usb wall supply (old iphone cube). When I want to control on time for morning coffee, I plug in USB to a timer switch (doesnt need to be high current) and leave the machine on. Or you can alternatively place main power as well on a timer that manages high current. When adding SSR, pay attention to the SSR heat sinking.

If properly setup, HX Temperature stability, as measured with SCASE equals my single boiler pid.

As you will learn when you peal back more layers to all this, the E61 was originally intended for an HX machine - with pstat. So if you want to retain historical functionality, yet make it more reliable, the pstat/ssr may be a useful option.

More trivia, HX water is fresher then single boiler, but dont offer as much ability to manipulate pressure during shot. Single boilers can act like a capacitor in an electrical circuit. One can pre- build boiler pressure with pump switch, or conversely use boiler pressure only to finish shot. HX just don't have the same give there, as your water source is in a tube. Almost makes vibe pumps seem like rotary pumps because the pressure is direct. Flushing is done for both temp control and to remove vapor in the HX tube caused by static water heated to the high boiler temp. Others have elaborated on all this in other threads.

Hope this helps. Many knowledgeable folks here, home-barista contributors have been of great benefit to me over the years. Thanks to all contributors!


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#8: Post by cafeIKE »

One benefit of a PID is NO CLACK.

Dinner party guests frequently asked "What's that clicking?"

Napoli (original poster)

#9: Post by Napoli (original poster) »

Thanks for the inputs
I will consider pstat/ssr ruote as i want to mess with this beauty the least possible.
Plus flushing doesn't bother me that much.
Anyway these mods would be done by a technician as they exceed my knowledge and abilities.
Another question: do you recommend distilled water for the boiler only to reduce scale?
Thanks again

Team HB

#10: Post by JRising »

Napoli wrote: Another question: do you recommend distilled water for the boiler only to reduce scale?
No, but I strongly suggest testing your water hardness, PH and Chloramine levels and using a decent water softener specifically designed for "steam producing food equipment".