Does relocated Profitec Pro 500 SSR require thermal paste? - Page 2

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

As an electrical engineer I have done some work with thermal design. Most parts that pass large amounts of current will have a metal tab attached to the outer case. If you look at any metal surface under a microscope, it is not smooth. Connecting the metal tab to a larger metal heatsink sometimes is worse than nothing, because if it makes a bad thermal bond (especially if you are in a damp environment and moisture gets at the metal surface and you get a bit of oxide), the heatsink can act as a blanket. In the old days I would have students heatsink the older AMD athlon CPUs which were notorious for burning themselves up (before they had thermal shutdown). Some would forget heatsink compound and it was a "campfire". We never used pads. I can't really talk about pads today, but back then paste was best.

Although one can use thermal pads, good heatsink compound, like arctic silver, or equiv works very well. Its the same premise as adding a thin layer of cooking grease to a pan, and the rosin inside solder.. it acts as a heat bridge to evenly distribute the heat into or out of devices.

If using heatsink compound, the thinner the layer the better. Too much and you get a weak sheer bond and a worse transfer to the heatsink.

Having a Pro500 PID myself, you may have read posts of my issues with it; and Profitec's seemingly ambivalence to issues I had with my unit. Their manuals also are not accurate for their HX in order to get the best performance from their machine. The SSR failure I and others had was with 2018 units and although they still mount in the same place, it might be a different part now that can handle more current.. I haven't checked.

To do proper thermal design you need to know the operating ambient temp at the mounting point, and the thermal resistance of the heatsink and other thermal properties of the SSR itself. Not terribly hard to do, but not something the user should have to get into. The higher the ambient temp, the larger heatsink required. If the ambient is too high, no amount of heatsink will cool. But the thermal resistance of the joint between the heatsink and the part is part of the equation as well. You always want this to be as low as possible.

I suspect (and only suspect) that Profitec did not do a great job designing their original PID system (that first used the SSR) for 110v vs 220v systems. In the 220v world, the current is 1/2 of what runs in a 110v system. This is because the power (P = V*I) of the heater must be the same. Less voltage (110 vs 220) and more current is required to get the same power. So the current flowing through the wires and SSR is double and maybe Profitec did the design of its SSR based only on a 220v system.. Just a guess. I'm sure they read these forums so unsure why they haven't made that part of the design more robust. Based on my machine they should also increase their restrictor size.. but another story. Edit: Now maybe the have put a heavier duty SSR into newer machines, but used the same mounting location..

I have also heard some stories of failures of other manufacturer's machines because wires were too thin for the amount of current going through them.. so if a company designs for 220v and uses the same wires and connectors for 110v, this can also be an issue as the wires and/or crimps can heat up causing hot spots, which increases their resistance, which heats up faster.. heat = I * I * R.. and you get a "runaway" melt down event. In a recent thread on this topic you see pics of a user whose terminals on their heater basically melted.. Now that can come from bad crimps or water.. but also can be caused from improper size of wires and quality of crimps (crimps are rated for current passed).

But short comment..If I was going to relocate.. I'd use paste .. and relocate to bottom and back of unit.. other companies use this location for their SSR. Slight chance water could pool there if you get a bad leak.. but likely you'll have lots more to fix in that case. You could also add a heatsink (any is better than none) and elevate it a bit in the back. You'll need to add longer wires and crimps so ensure they can handle the current.I would not trust the adhesive of pads.. they can dry and weaken.. and as mentioned.. this joint is critical for good thermal transfer.. .. A good bolt down is something I'd trust more.

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cafeIKE
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#12: Post by cafeIKE »

Heat kills electronics.

Since the chassis painted, it likely not stainless, so relatively easy to work and better thermal conductivity.

Ideally, the rear of the machine and mount the heatsink so there is a vertical air flow through it. Mark the location of the SSR and remove the paint on both sides. You can score the paint through to the metal and make a perfect footprint.

Mount the SSR and heatsink with thermal paste [only a thin even film is required] and secure with nuts and bolts. DO NOT over tighten!
civ wrote:I have not had to even look at it in 10+ years.
One of mine is going on 16 years and the other 14. Properly sized and installed, they will outlive me.

rbax238 (original poster)
Posts: 47
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#13: Post by rbax238 (original poster) »

Bluenoser wrote:As an electrical engineer I have done some work with thermal design... Having a Pro500 PID myself, you may have read posts of my issues with it
Hey "hi", yes I've read (and reread) your posts on your temperature adventure. I read them when I first got my machine and I couldn't follow the issue. Over time, however, and with other study, I went back and read them again after I could understand what a "restrictor" was and WTH was going on. I still think your specific machine runs cooler than mine, but I would claim the same surprise as you over what I was sold in sales/marketing copy versus the reality. TBH my two biggest influences on choice of machine were my wallet and years-long sales advice to move up from my Breville Oracle to an E61 HX "big boiler" machine in order to get stronger steaming. Over all, however, I know that I got the best I could afford that offers a Flow Control facility, something that I absolutely insist upon having (thus there is no better machine for me that I can afford). I'm having a hellava lot of fun and enjoying some great coffee.

SSR

I was an Electrical/electronics tech too many decades ago. I did return to school to get my elec eng degree but I didn't work in it long. "Personal Computers" were becoming a thing and I jumped over to spend my career in software. Here's what years in electronics repair and a university degree plus brief work in the field taught me: "don't confuse the science with the practice." It's also said as "in theory, Theory and Practice are the same; in practice they are not."

I could go and measure temperature fields around the device, review spec sheets, etc. and design a solution from first principles. However, this would be silly (and a lot of work). Alternatively, I could throw a bigger current carrying SSR onto a bigass heatsink, and with a little paste, bolt it to the case back in the cooler parts of the machine. This would be easier, quicker, cheaper, and probably give less headache and problems in the future.

Thus I really wanted to ask the question of people who had dealt with this before. What did they do? What do they recommend? Thermal Pad not recommended? Check. ".. A good bolt down is something I'd trust more...". Bolt down, sure. Gonna do that.

I look at the metal panel the SSR is bolted to - it's "heat sink" if you will, and I think "oh, this doesn't really require much of a heatsink at all" (because they didn't give it much of one). BTW I too looked at the size of the current carrying wires. Boy those are none too big. If I didn't know better I'd say they were designed for 220v (ie. half the current). But this is "German designed". They wouldn't do that!

Aside from a great sale price (with the Flow Control thrown in and installed) I wanted "Profitec" because I wanted something well-made and easy to work on myself. After transporting my old Breville Oracle (the first) four times to repair, I wanted something that doesn't have to be sent in for repair. I'll do it myself, but I won't have to because this is so well made that it'll never break and I need to will it to my children. <mmm... grumble>
Now maybe the have put a heavier duty SSR into newer machines, but used the same mounting location..
Yeah, I'm going back inside to get the SSR ID numbers/specs off of it (hopefully). I thought I could get that info online but I cannot find any details. I certainly HOPE the SSR is rated for more than 10A (that seems to be a popular SSR size) for this machine on 120V. Lessee... 1400W boiler on 120V is ~12A. From the charts here in a previous post you can see that the capacity is halfed in an environment of 40C. So that SSR should be 25A minimum.

Non-SSR
Having a Pro500 PID myself, you may have read posts of my issues with it; and Profitec's seemingly ambivalence to issues I had with my unit. Their manuals also are not accurate for their HX in order to get the best performance from their machine.
Frankly, I am rather underwhelmed by their "User Manual." I think the manufacturer leaves "user issues" with the retailers. (Still, their apparent lack of interest in the end customer was unnerving). Their answer of "get a P700" told me everything, though. To me, the big disconnect here is with simultaneously promoting the machine as "great for entertaining, with strong temperature control via PID" and encumbering it with a restrictor which can (almost) offer a "no-flush" single shot pull (why?) while crippling its multi-shot performance. I suppose they found that most users really only ever pull one or two shots with this machine. I do. I don't suffer any low-temperature issues.

After reading your experience I would have gone out the next day and slapped a brewhead thermometer on it, except I'm having too much fun with the FC and its brewhead manometer. Sigh. Why can't someone make a Temp/Pressure combo meter for this machine?

I do think the machine materials are good (with the exception of the sizing/location of the SSR) and it is easy to work on (compared to other machines). I may not know "the number" of the temperature of water hitting the puck, but I can easily, consistently reproduce the same workflow to get consistent results that I like and it's flexible enough for me to experiment with all kinds of things. Would I now consider upgrading to a P700? No, that would get me very little for the money. It would have to be a good profiling machine like a Crem One R-LFPP or Decent. Oh and the grinder would have to be one of those telescope-looking things designed by the likes of Apple.

rbax238 (original poster)
Posts: 47
Joined: 2 years ago

#14: Post by rbax238 (original poster) »

civ wrote:I have not had to even look at it in 10+ years.
Well that is certainly encouraging.
====

Ok, dumb question, how do you upload a jpg to insert an image? When I click on the image button all it gives me is the "img" html tags. If I put a imgur url inside of the tags I cannot submit. What am I doing wrong?

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civ
Posts: 1148
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#15: Post by civ »

Hello:
rbax238 wrote: ... certainly encouraging.
It is, if it is done right.

There is not too much $$ difference between a 15A SSR and a 40A SSR and the peace of mind is well worth it.
The graphs I uploaded for you and tell the whole story are for a Caho SRA2540 which should be a perfect drop-in repacement if you need one.
rbax238 wrote: ... dumb question ...
No such thing.
rbax238 wrote: ... how do you upload a jpg to insert an image?
What am I doing wrong?
You read the FAQs?
Go to the the FAQs page, then to the Read me: tips on site usage and then scroll down to [new members] Posting images on HB.

Easy Peasy ... 8^D

Cheers,

CIV

rbax238 (original poster)
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#16: Post by rbax238 (original poster) »

Okay, so it is a 20A (240V) SSR.


rbax238 (original poster)
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#17: Post by rbax238 (original poster) »

vv

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rbax238 (original poster)
Posts: 47
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#18: Post by rbax238 (original poster) »

civ wrote:You read the FAQs? Go to the the FAQs page, then to the Read me: tips on site usage and then scroll down to [new members] Posting images on HB.

Easy Peasy ... 8^D
LOL. Dunno what that Image button is for at the TOP, but it prevented me from seeing the GREYED OUT "image" tab AT THE BOTTOM.

Thx muchly!

BTW I was able to add the pic either by using the FAQ method with the Image tab or else by just dragging&dropping the file onto the msg itself. The FAQ/Image method left a 3.5M file whereas the drag&drop left a 555k file (although both are still way too high a resolution).

rbax238 (original poster)
Posts: 47
Joined: 2 years ago

#19: Post by rbax238 (original poster) »

BTW, I forgot to mention that "after the experimental relocation", I thought it best to return it to it's original position until I can get some thermal grease and some nuts&bolts and start drilling holes. Wasn't very confident with the thermal conductivity of zip-tying it to the painted chassis.

PS. It's amazing what passes for a "heat sink" these days.


rbax238 (original poster)
Posts: 47
Joined: 2 years ago

#20: Post by rbax238 (original poster) »

While I was working on the machine my dear wife walked up behind me to give me a hug and whisper in my ear. She's enamoured by my technical prowness. She said:

"You just couldn't leave it alone, could you? Had to open it up. Please don't break it just yet."

Yeah. I'm kind of a hero to her. She adores me.