How to connect pressurestat thru SSR to reduce load?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
maki
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#1: Post by maki »

espresso machine: La Marzocco Linea Classic, 1 group.
my current pressurestat is on its last miles so i bought a replacement.
instead of a XP110 i got a CEME one, for the possibility to adjust the deadband and honestly it was the only one available at the moment.

now, i read somewhere that it wouldnt handle large currents and it would be better to connect it thru a SSR.
okay, no prob, i have one at home too, a 40A DA.

now how do i connect it? cant figure it out.

here's the electrical schema:
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boost
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#2: Post by boost »

If I recall correctly CEME pstat are rated for 10A and a Linea 1 group only have 1300 element so it is well within the spec.
On 2/3 group Linea the pstat would actually control a contactor but some Sirai pstat can directly handle it as well.

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Jake_G
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#3: Post by Jake_G »

What's written below isn't particularly useful since this is a steam boiler. But I've kept it anyway since it doesn't cause anyone any harm to see that I am often times dumb...


Fair point, as documented here. But maki has shown interest in adding a PID to his linea in the near future. Since he has the SSR on hand, I think this would be a logical step in the right direction for him. Some rewiring will be necessary anyway since his old pstat is a 4 wire, so adding the SSR should be a minor addition. The SSR should also pretty much guarantee that he will never need to change a pressurestat again...
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erics
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#4: Post by erics »

now how do i connect it? cant figure it out.
You could start by posting the correct wiring diagram for YOUR particular machine. The wiring diagram you posted depicts a double contact pressurestat which would typically be a Sirai. Even though the amperage draw for your steam boiler is within the design range of either of those pressurestats, I'm THINKING that LM installed a relay to energize the heating element.

The MA-TER and the CEME are comparable but I sure wouldn't try adjusting the deadband on the CEME. That small screw is not intended to be user adjustable.

Your "DA" SSR has low voltage control input so it is most definitely not suitable for this application unless you want to PID the steam boiler. That would not be beneficial on your machine.

Multiple pics of your machine's internals would be beneficial.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

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Jake_G
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#5: Post by Jake_G »

Good call, Eric. Should have paid attention to what was being asked before showing him how to do what he asked :wink:

In all seriousness, I very much dislike misinformation floating about, particularly when it has my name on it. I'm going to wipe my suggested schematic since it's a) terrible, b) not suitable to the SSR in question and c) putting the steam boiler on a PID is not really a helpful thing to do...

Sorry maki!

- Jake
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JohnB.
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#6: Post by JohnB. »

erics wrote: Your "DA" SSR has low voltage control input so it is most definitely not suitable for this application unless you want to PID the steam boiler. That would not be beneficial on your machine.
When I swapped out the steam boiler electronic controller in my Speedster for a p'stat I had to replace the old low voltage Comus SSR with a different Comus model that has a transformer.
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Nunas
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#7: Post by Nunas »

Notice if you trace the two white wires from the heater back to the incoming mains plug, one goes to black and the other goes to white. On 120-Volt appliances in NA, we only need to switch the black (hot) wire. On 240-volt appliances, we need to switch both (actually, on 240-volt appliances a W-R-G mains cable is incorrect usage). If your machine is a 120-volt version, you can easily and safely convert it to single pole switching. If it is a 240-volt version, you must use double pole switching. I won't go any further in this regard until I know if your machine is 120 or 240 Volts, for safety sake. Is your SSR a DPST or the much more common single pole; if it is SPST and the machine is 240-volts then it's the wrong one. Also what is its allowable range of control voltage (usually 3 to 30 volts or thereabouts). If you don't have an appropriate DC source in your machine (probably not), then you'll need to install a small power supply to run the SSR; the easiest way to do this is to scavenge a 5-volt USB charger board (or just put in the entire charger if you have the room).