Heat Sink Too Small for Mounting

So I'm running into a problem with building my electrical enclosure. I'm following Kal's build but I decided to use the smaller heatsinks that came with my SSRs. I bought the SSRs from ebay and they just like the small heatsink/ssr combo below (middle picture).

The problem is that where the heatsink and SSR attach to each other is almost exactly the same size. This leaves me no room to mount the heatsink to the enclosure like Kal did (first picture). Looking at the heatsink that Auberins provides it shows to have a much larger mounting surface which eliminates this problem (third picture below).

Has anyone run into this for their build? I'm not sure how to overcome it without buying a new large heatsink.

Firstly the owner of Auber is going to tell you that you need the larger heatsink if you are running 40 amp SSR's, so I took his advice when I bought. I assume that is what you have. If you're dead set on using the smaller (undersized?) sinks, how about a smaller opening and mounting the sink with the first level of plates inside your panel. I'd cut a piece of cardboard or wood and play around with the hole size, making sure you can slip the sink in at an angle.

samc said:

Firstly the owner of Auber is going to tell you that you need the larger heatsink if you are running 40 amp SSR's, so I took his advice when I bought. I assume that is what you have. If you're dead set on using the smaller (undersized?) sinks, how about a smaller opening and mounting the sink with the first level of plates inside your panel. I'd cut a piece of cardboard or wood and play around with the hole size, making sure you can slip the sink in at an angle.

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I thought about mounting it with the first level of plates inside. That's a good suggestion to use a piece of wood for practice. I'll probably give this a shot before I put more money towards new parts. The auber instrument sinks are bigger but they don't seem to be that much bigger. I'm also running an SSR that is oversized (40amps capacity) for my application so I don't forsee the heatsink being undersized for my build. However, I'm a novice.

Are you using a metal enlosure? If so why not drill the mounting holes only in the enclosure and sandwich it between the heatsink and SSR. Heat will transfer to the enclosure, then directly to the heatsink.

Navy_Brewer said:

Are you using a metal enlosure? If so why not drill the mounting holes only in the enclosure and sandwich it between the heatsink and SSR. Heat will transfer to the enclosure, then directly to the heatsink.

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It is a metal enclosure but I don't think the heat transfer would be very good from the SSR through textured paint. It's an interesting idea but if this was acceptable why would anyone cut a hole in the panel simply to mount the SSRs to the heatsink? As of now the surfaces of the SSR and heatsink are very smooth allowing good heat transfer. To place both the heatsink and SSR onto the textured paint with unknown heat conductivity isn't something I'm crazy about.

I'm in the same boat. Since I'm using a metal enclosure, I also thought about sandwiching SSR/enclosure/heat sink, but first would sand the paint off the enclosure to bare metal.

Currently, I have my 40A SSR mounted to my heat sink, both INSIDE my metal enclosure panel. The heat sink is mounted directly to a wall of the metal enclosure. Since I am only running 23 amps max, i'm hoping the SSR doesn't get too hot. When I finally do a test run, I will operate and take temp readings first when panel is open and then closed.

I just now purchased this heatsink. I found it from a thread on Kal's website where others purchased this and had good results. If you click on the link now one will not be listed but this happened to me last night and he/she posts another one quickly. They are currently $20 with $10 shipped. I thought about purchasing the custom built one from Kal's site but this was cheaper and I will get it much quicker. Not discouraging anyone from buying from Kal, this was just why I chose this heatsink.

http://cgi.ebay.com/ws/eBayISAPI.dl...CYHmPZZZ3UxU%2Bdmw%3D&viewitem=#ht_500wt_1129

The thread on Kal's site.
http://www.theelectricbrewery.com/forum/viewtopic.php?t=24587

I ran into the same issue. I tried to make the cuts as close as possible, but I still did not like the fit. I ordered the larger heatsink. I was thinking though, instead of mounting the removable plate. Get a roll of aluminum flashing, cut it to the same size, caulk it and screw it on. Then you can sandwich between the two. If the flashing has any coating, a light sanding will remove it.

milldoggy said:

I ran into the same issue. I tried to make the cuts as close as possible, but I still did not like the fit. I ordered the larger heatsink. I was thinking though, instead of mounting the removable plate. Get a roll of aluminum flashing, cut it to the same size, caulk it and screw it on. Then you can sandwich between the two. If the flashing has any coating, a light sanding will remove it.

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I tried a whole bunch of methods to make it work last night including cutting a surgically sized hole that was just big enough for the SSR but just small enough for the heatsink. Nothing worked and I wondered why they even wasted the money making the heatsinks as they are useless for our application.

I found the larger heatsink from your posts on Kal's discussion forum. Thanks! Are you suggesting not buying a different heat sink but installing what I have onto aluminum flashing? What did you end up doing? I already ordered the larger heatsink and I think I would rather go that route than aluminum flashing. I figure I'm spending all the money on this control panel so an extra $30 for the proper and larger heatsink is fine with me. It will work better anyways and look much better.

Scut_Monkey said:

I tried a whole bunch of methods to make it work last night including cutting a surgically sized hole that was just big enough for the SSR but just small enough for the heatsink. Nothing worked and I wondered why they even wasted the money making the heatsinks as they are useless for our application.

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Those heat sinks are made to be installed inside the enclosure. They have tabs on them so that they fit a DIN rail if desired. It is not necessary to cut a hole through the enclosure. I remember Kal saying that his heat sink doesn't even get warm.

I have a plastic enclosure, and didn't want the heatsinks on the inside because I didn't want to deal with ventilating the thing. My solution was to cut an oversize hole and bolt on a piece of aluminium as milldoggy suggested. Then I bolted the SSR's to the heatsinks through the aluminum plate. I spread thermal grease on both the heatsink back and the SSR mating surface. Here's a picture of what I'm talking about:





You could use this same thing now that you've cut holes. The aluminum has great thermal conductivity, so it'll transfer the heat to the heatsink quite well. For the thermal grease I used this from RadioShack.

I also went with 40A SSR's to switch <30A. What I have found is that the heatsinks get warm but not hot without any forced air cooling. I wouldn't recommend using them without heatsinks, though, and I would also be very wary of running them inside the enclosure without the use of a fan to move air across them. My enclosure gets up above 30 C inside when the ambient temperature is around 15 C. This isn't too bad, but I would be concerned during the summer months if the heatsinks were internal.

trigger said:

I have a plastic enclosure, and didn't want the heatsinks on the inside because I didn't want to deal with ventilating the thing. My solution was to cut an oversize hole and bolt on a piece of aluminium as milldoggy suggested. Then I bolted the SSR's to the heatsinks through the aluminum plate. I spread thermal grease on both the heatsink back and the SSR mating surface. Here's a picture of what I'm talking about:



You could use this same thing now that you've cut holes. The aluminum has great thermal conductivity, so it'll transfer the heat to the heatsink quite well. For the thermal grease I used this from RadioShack.

I also went with 40A SSR's to switch <30A. What I have found is that the heatsinks get warm but not hot without any forced air cooling. I wouldn't recommend using them without heatsinks, though, and I would also be very wary of running them inside the enclosure without the use of a fan to move air across them. My enclosure gets up above 30 C inside when the ambient temperature is around 15 C. This isn't too bad, but I would be concerned during the summer months if the heatsinks were internal.

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Thanks for the pictures and detailed response. I already ordered the larger heatsink so I'm going to go this route. However, the aluminum divider seems to be a good method based on your pictures and both of you describing the exact same thing. Yeah I would not want the heatsinks internal. Perhaps it's safe, perhaps not. I just don't have enough experience with electronics like this to stray from what's proven to work well.

I'm in the middle of cutting all the holes for my control panel now. It's a bit of work. I'll be glad to be done with all the metal work. I was getting quite tired of working on the keggles by the time I finished them.

Here was my solution... 1/8" aluminum plate with 7 heat sinks on the outside and 7 corresponding SSRs on the inside. I used thermal paste on both sides of the plate.

Wow that some intense SSR action. Beautiful wiring inside.

Well I just finished punching and cutting all the holes for the control panel. I'm waiting for some JB weld to dry on it for the repositioned ground post. Tomorrow I'll be sanding, painting and priming the enclosure. I'm so tired of working with metal with the enclosure, keggles, HERMS coil. Argh! I'm glad I'm almost done with that and onto wiring.

Wow, that ebay seller is getting greedy. I purchased that same heatsink from them a couple months back for the stated $10 + $10 shipping. The seller raised to 15 + 10, 20 + 10, and now currently 25 + 10. Why can't sellers not screw over customers just because they can? Obviously they were making money selling them for $10 + $10. Why raise the price 250%?

As Quaffer said, they are made to fit inside the enclosure. There's really no reason to mount them outside honestly. If you were really worried about heat in that situation you could just cut a hole in the enclosure as a vent or install a small computer fan in the box to vent it and you'd be set.

I used the larger sink. It looks nice and I bought it. The next time I build one, I am going to mount an aluminum plate instead of the removable plate.

Looks like you got some great answers from other people.

Tested my control panel last night, with a 40A SSR and heat sink mounted INSIDE a metal spa panel. While running a 5500 watt element, I was very surprised how hot the rear of the spa panel got. It wasn't hot enough to burn my fingers, but was uncomfortable. My temp gauge wasn't working, but it was equivalent to holding a hot cup of coffee.

TheZer said:

Tested my control panel last night, with a 40A SSR and heat sink mounted INSIDE a metal spa panel. While running a 5500 watt element, I was very surprised how hot the rear of the spa panel got. It wasn't hot enough to burn my fingers, but was uncomfortable. My temp gauge wasn't working, but it was equivalent to holding a hot cup of coffee.

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Interesting. Was this during the boil, mash, temp ramp? I did purchase the larger heatsink and installed it this weekend. It looks great and much more professional than the heatsinks that come with the SSRs. I mounted it externally. I have seen multiple threads this weekend about failing SSRs so I'm glad heat will be less of a concern with me.

Scut_Monkey said:

Interesting. Was this during the boil, mash, temp ramp?

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Both 5500 W elements were 100% on upon reaching 170 in the HLT and 212 in the BK, but not at the same time. As I said, the spa panel got pretty hot.

When 170 was reached in the HLT, the element was throttled back by the PID, and the panel cooled down a bit. Same goes for the BK.

I've decided to sandwich the rear wall of the control panel between the SSR (internal) and the heat sink (external) since it only involves drilling a few holes and some sanding.

TheZer said:

Both 5500 W elements were 100% on upon reaching 170 in the HLT and 212 in the BK, but not at the same time. As I said, the spa panel got pretty hot.

When 170 was reached in the HLT, the element was throttled back by the PID, and the panel cooled down a bit. Same goes for the BK.

I've decided to sandwich the rear wall of the control panel between the SSR (internal) and the heat sink (external) since it only involves drilling a few holes and some sanding.

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The steel box will not have the same thermal transfer capacity as the aluminum heat sink. If you are already concerned about heat, I think "sandwiching" the box wall between the SSR & heatsink will cause more problems.

Ed

Ohio-Ed said:

The steel box will not have the same thermal transfer capacity as the aluminum heat sink. If you are already concerned about heat, I think "sandwiching" the box wall between the SSR & heatsink will cause more problems.

Ed

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Yea, i figured the steel would act as an insulator when compared to the aluminum, but if the steel is thin enough, the aluminum heat sink would pull the heat off pretty quickly. Since this is a 5 minute project, I figured I give it a try before cutting the panel up.

bbognerks said:

Wow, that ebay seller is getting greedy. I purchased that same heatsink from them a couple months back for the stated $10 + $10 shipping. The seller raised to 15 + 10, 20 + 10, and now currently 25 + 10. Why can't sellers not screw over customers just because they can? Obviously they were making money selling them for $10 + $10. Why raise the price 250%?

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no kidding.. I bought it at 20+10, figured it was a better heatsink than 4 of the regular ones and it worked nicely - but yeah, I wish they'd leave the price alone.

bruin_ale said:

no kidding.. I bought it at 20+10, figured it was a better heatsink than 4 of the regular ones and it worked nicely - but yeah, I wish they'd leave the price alone.

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30+10 now. If you don't mine tapping your own holes, HeatsinkUSA has non-anodized ones of a similar size (about one inch wider) for $10 + calculated shipping. Sure that it would be considerably less than the recent markup on the previous link, still.

HeatsinkUSA - 4.23" x 8" Long x .75" Fin Height

jmferris said:

30+10 now. If you don't mine tapping your own holes, HeatsinkUSA has non-anodized ones of a similar size (about one inch wider) for $10 + calculated shipping. Sure that it would be considerably less than the recent markup on the previous link, still.

HeatsinkUSA - 4.23" x 8" Long x .75" Fin Height

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good to know.. I found old cpu heatsinks at the local surplus, but nothing that looked like it'd work as well as the e-bay one. I'll admit, it was nice having everything tapped and ready to go - but not worth $40. $30 was a stretch, but after spending hundreds of dollars on all the other stuff and that being one of the last things I needed, I didn't really care at that point.

bruin_ale said:

$30 was a stretch, but after spending hundreds of dollars on all the other stuff and that being one of the last things I needed, I didn't really care at that point.

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That's where I am at. $30 isn't much by the end of all of this. I figured I should get something that worked well and not compromise the integrity of the enclosure by installing something somewhat makeshift. For $30 it's not bad but $40 is getting up there. Although if they don't sell at $40 the price will lower.

yeah, sorry I gave them positive reinforcement by purchasing at $20+$10 shipping.. wasn't prepared to wait them out until they lowered the price.

bruin_ale said:

yeah, sorry I gave them positive reinforcement by purchasing at $20+$10 shipping.. wasn't prepared to wait them out until they lowered the price.

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Supply and demand is a fickle beast. Kal seems to have created demand for more than a few products with his build.

Ohio-Ed said:

Here was my solution...

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That is crazy! Why all the ssr's for what looks like two elements?
BTW, where did you get the panel?
Really nice!

Rondacker said:

That is crazy! Why all the ssr's for what looks like two elements?
BTW, where did you get the panel?
Really nice!

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Thanks.

Three elements (HLT, BK & RIMs), two pumps for a total of seven hot legs all controlled with SSR's.
I got the box (Console), from a user here on HBT, the back plate is just a piece of 1/8" aluminum.

Ed

I'd love to see a build thread or journal.
I'm in the R&D stage of a system.
Lots of nice work around here..

Rondacker said:

I'd love to see a build thread or journal.
I'm in the R&D stage of a system.
Lots of nice work around here..

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Most of the work in the panel is covered here:
https://www.homebrewtalk.com/f170/electric-question-153310/

Thanks, I'll check it out.