civ wrote:Hello:

I am now in the process of setting up my PID/Pt100 rig to control the boiler. I will keep the Sirai working at a higher temperature (ie: pressure) to act as a back up. I'd be very obliged if you'd let me know which of the heater coil wires you intercepted to connect the SSR ie: the one before the coil (coming from the Sirai) or the one after the coil (to the On/Off rotary switch in the box under the drip tray).

In a few days I will also be changing that rotary switch for a three position model: 1/0/2 instead of 0/1.
Position 0 will remain at centre as 'Off', Position 1 (left) will power everything 'but' the heating element and Position 2 (right) will power everything, like Position 1 with the old switch.

I was really not very comfortable doing maintenance (eg: boiler cleaning, emptying and re-filling) knowing the heater coil was on.

Bonjour from CDG Airport in Paris

I missed my connecting flight to Lyon so I logged on and found your post. I am obviously not home and have no access to my machines, and will not be back home for a month. Everything I'm writing below is from memory.

I have two Cimbali Juniors, neither of which are the same model as yours, so what I did with my machines' wiring may not be the most reasonable thing for you to try to adapt to your machine.

My D/1 rotary machine does not have a Sirai, rather it has a Cimbali branded Pstat located in the far back of the machine. This Pstat is microswitched through a relay, and I don't remember exactly were the relay is located. What I did with that machine was to leave the Cimbali Pstat in the circuit and all of my control was after that point in the wiring. I set the stock Pstat to a high temperature that was below the red line on the front panel gauge. I forget exactly where I set it but I think it was around 1.4 bar to 1.5 bar. As long as the installed Pstat has the circuit on, the actual boiler temperature is controlled by the PID, and the Pstat serves only as a safety in the circumstance, for example, of a broken PID or SSR stuck in the "on" position. I believe that the wiring of your D/1 machine is so different than mine that this approach may not be workable, but I'm not familiar enough with your machine to know. The actual wire that I control with the PID is one of the two wires going into the element itself, switching that wire through the high voltage side of the SSR.

My S Vibe pourover machine, circa 1995, had a Sirai Pstat, but I removed it as there was no other easy place to insert a probe for the PID, than the port connecting the boiler to the Sirai. In this machine there is therefore no remaining Pstat nor is there the potential safety factor of having the backup Pstat to stop the boiler temperature from rising high enough to blow the boiler ("pop") safety valve. I don't think that this is a significant risk, given the presence of the "pop" valve, but it is something to be aware of. If my memory serves, I used the wires that went originally to the Sirai, with booted connectors, for the outputs from the SSR controlling the boiler element, and I got power for the PID itself from the power cord coming into the machine in the undertray electrical compartment.

So, there are in actuality two issues. One issue is the wiring, and the other issue is where do you put the PID thermocouple probe into the boiler. I don't know what your boiler looks like or how many free ports it might have for putting in a probe.

Hello Ken:

Ken Fox wrote: Bonjour from CDG Airport in Paris

Niiiice ....

Ken Fox wrote: I missed my connecting flight to Lyon so I logged on and found your post.

Thanks for taking that time to post, I really appreciate the gesture.
I would have probably been checking out the chicks ...

Ken Fox wrote: I have two Cimbali Juniors, neither of which are the same model as yours ...

Yes, I'm aware of that.
But your S1 is more or less of the same vintage as mine (2000), and from what I have seen it seems that those Junior models had (?) the same boiler and Sirai, which is why I asked. I think that up to the time the 100% electro-mechanical models (rotary switches, relays and Sirai volume/level control under the drip tray) were discontinued, all Juniors had the same boiler and a Sirai.

I have seen that the new Cimbali Junior models have, as you point out, a new Cimbali issue pstat (apparently not a well finished piece of hardware) and a totally different boiler, made in SS.

Ken Fox wrote: My S Vibe pourover machine, circa 1995, had a Sirai Pstat, but I removed it as there was no other easy place to insert a probe for the PID, than the port connecting the boiler to the Sirai.

Indeed ...
I have seen that the new models have extra ports (OEM boiler manufacturer's compliment) so it would be an easy enough affaire. I came across the same problem as you but at the time I was not too clear as to the addition of a PID to the Junior being permanent, so I attempted to devise a way to make it removable.

I came up with this design, which seems to work well.

First I went through my stash of brass fittings and found a 1/8" BSP thread female 'T' and purchased three bits of 1/8" BSP brass threaded pipe. 1/8" BSP thread is the same thread as the the Serto connectors used all around the Cimbali.



Then, using the 1/8" BSP theaded brass pipe, I changed the gender of the 'T' to 'M', cutting each piece of pipe to the length required to keep the piece on the same pair of axis of the original 90° 1/8" x 1/8" F Serto fitting. ie: one axis coming straight out of the boiler and another one perpendicular to it going down to the Serto connector on the end of the 5.0 mm tubing that goes back to the Sirai.

All this was for easy assembly while avoiding the possibility of introducing stress to the existing piping, something that I don't think would have been possible with a female 'T'. And this sample was at hand.

I must mention that having wreaked havoc trying to braze another sample (and ruining it in the process), the 'T's different parts are held (very) firmly in place with the red Loctite used for loose threads (cannot recall which number it is). I have read that this stuff could be toxic if it came into contact with boiler water, but that should not happen.

On one hand, it is well above water level, immersed in steam and not actually entering the boiler volume.
On the other, I was very carefull when applying it (only at the end of the threads) and then to clean all visible residues with a 'Q' tip and medicinal alcohol before it had set and then with a thin scrawl once it was hard so as to leave no trace of it in sight. Of course, I have been monitoring the taste and smell of boiler water (once cooled) and for the moment I can smell/taste nothing strange.

In any case, I am not at all sure that the silver braze I had at hand was cadmium free either. =-o!



I have a certain dislike for Serto connectors basically because they seal flat against flat and require force to tighten, just like BSPT fittings. Happens that I have a very poor track record with respect to tightening threads and such. Please don't ask.

Besides that, they are not available locally.

Owing to this, I had to take special care so that the end of the 1/8" BSP threaded pipe (blue ring) where the Serto fitting had to mate had a flat surface and also that it was perpendicular to the fitting's axis. Fortunately, I managed to get it done and it's been working quite well, remaining watertight ever since it was put in place.

As I don't have a torque wrench, I was rather nervous while I tightened it.

The new port had a 1/8" BSP 'M' plug (red ring) in place while I got the Pt100 probe ready and recalibrated the PID. It was then drilled out and a blind piece of SS tubing (from the digital thermometer that monitors the brew-head temperature) was brazed in to hold the Pt100 probe, which is in turn inside another, thinner length of tubing.



It slides in with a just wee bit of play and I use a good amount of thermal grease to assure good contact between the probe and the port tubings.

Ken Fox wrote: ... potential safety factor of having the backup Pstat to stop the boiler temperature from rising ...
... a significant risk, given the presence of the "pop" valve, but it is something to be aware of.

I agree ...

Ken Fox wrote: ... used the wires that went originally to the Sirai, with booted connectors ...

Makes perfect sense.
You replaced one relay (pstat) with another (SSR).

Ken Fox wrote: ... power for the PID itself from the power cord coming into the machine in the undertray ...

Yes, I will also get power for the PID from the 'On/Off' rotary switch in the box under the drip tray (btw: that is one lousy drip tray, I have seen how you fixed a broken one.)

Ken Fox wrote: ... in actuality two issues. One issue is the wiring ...

I am thinking that the best thing would be to intercept the cable that goes from one of the lugs of the heater coil to one of the lugs of the thermal safety switch. The SSR would then be after the pstat and before the thermal safety switch. This seems (to me, corrections welcome please) rather counter-intuitive as it would be logical that that the back-up controls be at the end of the boiler temperature control chain ie: 1) PID 2) pstat and 3) thermal safety switch, instead of 1) pstat 2) PID and 3) thermal safety switch.

But then, both the pstat and the thermal safety switch are auto-reset, as they come back on when the temperature drops below the set threshold on these devices and that short piece of cable between the lugs I have mentioned above is of very easy access, can be removed / put back in place in a minute in case of a PID malfunction or replacement and doing it in this manner requires no modification of the original cabling.

Ken Fox wrote: ... other issue is where do you put the PID thermocouple probe ...

I think that one is solved, unless some adverse situation comes to hand.
Murphy is always around.

What is still under study is the location of the PID unit, as it has to be in a cool place but I am rather reluctant to put it outside the box, so to speak. I do think I have solved the location of the 40A SSR along with a computer issue heat-sink and will post photos when it's done.

Once again, thank you for taking the time to post.
Enjoy you trip thoroughly, mon ami.

Cheers,

CIV

Well, in case you run into trouble, there is a Swagelok distributor for Argentina - http://www.aadeca.org/aadeca_2008/catal ... usitec.php that has all the fittings you need with no brazing, soldering, or sealant required. Fittings especially designed for thermocouples and RTD's would be designated "BT" for bored through in the size you desire whether it be fractional inches or mm's.

The only thing I can add at this point is that the SSR can be mounted directly onto the bottom of the machine's case; the metal in the case will serve as a more than adequate heat sink, especially if you sand off any paint in the area of contact, and use thermal paste between the SSR and the case. I have tested this with a thermocouple (next to the SSR; to monitor the heat produced by the SSR in operation) before and posted my results in a long ago thread. I did this after talking with an engineer working for the company that manufactured the SSR. It would be a very good idea to buy and install one of those cheap plastic SSR covers to protect the electrical contacts were you to do this. They are available from companies like mouser.com

As to where to mount the PID itself, I have done that on the front bottom of the machine with the PID installed in a small metal project box. There are quite a few pictures of my machines which I have posted on prior threads and can be found by searching this website.

ken

Hi guys,

just a note, a metal plate is not a great heatsink and usually they work well only because the element that gets hot doesn't get too hot. If you have something that will definitely get hot and stay hot (an SSR that switches huge loads for example, not a overspec'd SSR in an espresso machine which passes current during the first 10min only and then only comes on for a second or so every few seconds) use a proper fin heatsink with the right thermal resistance and some thermal conducting paste/pad.

Regards,
dsc.

Hello Erics:

erics wrote: ... there is a Swagelok distributor for Argentina ...

Yes, thanks for the data.
I heard about them a few days ago.

erics wrote: ... no brazing, soldering, or sealant required.

Indeed ...
I'll have a look and give them a call.

Cheers,

CIV

Hello:

Ken Fox wrote: ... SSR can be mounted directly onto the bottom of the machine's case ...

Yes, it will work well, especially as it is over-rated in it's spec (40A), but I am not too keen on mounting it on the outside of the box, even if it is under it.

Ken Fox wrote: ... very good idea to buy and install one of those cheap plastic SSR covers ...

Quite so. I am currently on the look-out for a suitable one as this one came without one.

dsc wrote: ... overspec'd SSR in an espresso machine which passes current during the first 10min only and then only comes on for a second or so every few seconds ...
dsc.

Indeed.
As you can see above, that would be the case with the SSR I will be using with my Cimbali.
It's a Caho SR-D2540 rated at 40A.

My Cimbali D/1 runs 1800W @ 220V which would set it at 8.18A, a bit more should line voltage should drop by less than 9.5%. ie: 1800W @ 200V = 9.00A.

Here's a graph from the Caho site:


Source: www.caho.com.tw

My interpretation (corrections welcome) of the graph is that if 'free air mounted' ie: with no heatsink, it will handle a 9A load at ~30° C ambient temperature; and if mounted on a heatsink, it will handle a 15A load at it's max. ambient temperature of 80° C.

I think it will work with no problems, more so if under the operating conditions you describe in your post.

The passive heatsink I will probably use comes from an old Intel P200 MMX rig which had a dissipation of ~16.0W and a max. operating temperature of ~70.0° C.

Thanks a lot to both for your input.

Cheers,

CIV

Hi CIV,

I forgot you are running at 220VAC, thought it's 110VAC for some reason which of course doubles the current.

From my own experience I can add that running a 40A SSR with the Elektra (2400W I think), with the relay stuck to the frame, with some thermal paste on it, I could definitely feel the frame getting very warm to the touch. Still it's only for a couple of minutes, so the SSR should be fine even without a heatsink, suspended in mid air.

Regards,
dsc.

My original idea when I planned out the PID installations in my Juniors was to use a proper heatsink. It was only after calling tech support for the SSR Mfr. that the tech I spoke with suggested mounting directly without a heatsink. He had no question that it would work in this application without undue heat production, but suggested that if I was concerned I could test the theory by temporarily taping a TC in the vicinity to see the actual heat production. I don't remember the maximum temperature that I measured, but it was not of any concern the several times I monitored the setup from a cold startup, and in actual operation.

ken

Hello again:

Ken Fox wrote: ... original idea ... ... was to use a proper heatsink.

Same here.
As a matter of fact, this same 40A SSR was in service in another brewer (800W) bolted on to a large piece of sheet metal inside the box and it did get quite warm to the touch. In any case, my limited experience with electronic components tells me that heat, excessive or not, is not too good for them.

Ken Fox wrote: ... only after calling tech support for the SSR Mfr. the tech I spoke with suggested mounting directly without a heatsink.

And I'm sure he's right.
But should it fail, I wonder if the people at tech support won't ask you whether it was mounted on a heatsink or not, as their brochure most probably indicates.

As I'd rather mount it inside the box and not under it, the surroundings are bound to be warmer. Just in case, I'll be using an old P200 MMX processor heatsink from an IBM desktop machine and use one of the existing unused holes on the frame to mount the heatsink to it.



Once I have it mounted in place I'll add another photo.

Here's a photo of how the SSR with it's heatsink is mounted inside the D/1, right behind the 'L' shaped plate covering the rear of the boiler.



It is held on to a 'U' shaped piece of 10 mm. aluminium stock with holes at each end which is in turn bolted on to the frame through unused holes by means of self threading screws.

The first photo is taken from above with the top cover off and the back cover on. The second photo is taken from behind with the top cover on and the back cover off.

Cheers,

CIV

Edit: 29/04/10 - Added photos of how the heatsink/SSR combo is mounted inside the Cimbali D/1.