Pairing heatsink and ssr

[JONNYROTTEN]

I keep hearing "get a big heatsink" for SSR. Do they have to match for any reason? Like fins being to thick designed for something bigger and losing efficiency. Most 40a ssr's come with the pyramid type heatsinks. Can I just buy a macdaddy heatsink,drill some holes and screw the ssr to it. Saw some big used ones cheap

 

[Owly055]

Of course you can........ Just remember to use thermal grease where they come into contact for good heat transfer.


H.W.

 

[augiedoggy]

the cheap ones work fine too as long as you have ventilation to the heat sink... some mount the heatsink on the outside of the box and some use a fan to blow thru them...

 

[Ozarks Mountain Brewery]

think of a ssr like a computer processor, you really need a fan/heatsink combo, lots of thermal grease and it will never get hot, I went through 5 before I used a pc heatsink and fan now I won't use anything else

 

[augiedoggy]

think of a ssr like a computer processor, you really need a fan/heatsink combo, lots of thermal grease and it will never get hot, I went through 5 before I used a pc heatsink and fan now I won't use anything else

That may explain why my cheap ssrs work flawlessly even with the $3 heat sinks...I do use thermal grease and a fan.

 

[Owly055]

I have a rectifier I built nearly 30 years ago for a 300 amp AC welder, made entirely from GM alternator diodes in parallel. The huge aluminum heat sinks and fan have kept it alive all those years. Lots of tiny little diodes thermally bonded to big heat sinks.... they handle hundreds of amps. The thermal bond and heatsinks / fan make a HUGE difference.


H.W.

 

[JONNYROTTEN]

http://i.ebayimg.com/00/s/NTAwWDM3NQ==/z/Qm4AAMXQatBSbsV~/$T2eC16F,!)8FJiSFwTMfBSbsV+I2QQ~~60_35.JPG I bought this.For a couple extra bucks Im covered

 

[JONNYROTTEN]

I give up trying to post a pic. Time for a beer 7"L x 2 1/2" w $14

 

[haeffnkr]

think of a ssr like a computer processor, you really need a fan/heatsink combo, lots of thermal grease and it will never get hot, I went through 5 before I used a pc heatsink and fan now I won't use anything else

+1
Went screwed up one SSR before I had to replace it and THEN added a fan.

Make sure you run a fan or you will end up screwed some day in the middle of a brew session.

 

[JONNYROTTEN]

+1
Went screwed up one SSR before I had to replace it and THEN added a fan.

Make sure you run a fan or you will end up screwed some day in the middle of a brew session.

Even if the heatsink is oversized and on the outside of the box?

 

[Ozarks Mountain Brewery]

it really depends on your set up but I had that and still kept over heating now if you use the one like the electric brewery sure I think that will work, here is mine

 

[haeffnkr]

Even if the heatsink is oversized and on the outside of the box?

I would recommend it.

I did not at first.. my heatsink never got really hot but it was hot enough to screw up my SSR after 8 batches or so. So if you dont over time your SSR may go out.

So now I have a USB fan on top of the heatsink, not the big fan in the picture any more, and I have had no issues since.


https://www.homebrewtalk.com/f170/stuck-ssr-scr-system-will-not-stop-458824/

 

[doug293cz]

Direction of airflow over the heatsink is also critical. You want the air to flow parallel to the fins, and the ribs that anchor the fins. This is especially important if you don't have a fan blowing over the heat sink, and are depending on natural convection for air flow. Natural convection flows vertically, from low to high. Thus, you do not want the fins or ribs to be parallel to the floor in the operating position of the controller. I have seen pictures of heatsinks on the tops of controllers, with the fins parallel to the floor. This is the worst possible mounting choice for the heatsink.

Brew on

Edit: haeffnkr, I was writing this as you posted, and hadn't seen your pic before I posted. So, I'm not intentionally picking on just your configuration. Fan is a big improvement with that heatsink orientation.

 

[ChocolateMaltyBalls]

Direction of airflow over the heatsink is also critical. You want the air to flow parallel to the fins, and the ribs that anchor the fins. This is especially important if you don't have a fan blowing over the heat sink, and are depending on natural convection for air flow. Natural convection flows vertically, from low to high. Thus, you do not want the fins or ribs to be parallel to the floor in the operating position of the controller. I have seen pictures of heatsinks on the tops of controllers, with the fins parallel to the floor. This is the worst possible mounting choice for the heatsink.

Brew on

Edit: haeffnkr, I was writing this as you posted, and hadn't seen your pic before I posted. So, I'm not intentionally picking on just your configuration. Fan is a big improvement with that heatsink orientation.

That would be optimal but part of getting an oversized heat sink is negating the need for a fan (exterior mounted) or optimizing the fin direction for air flow. In my own experience a big chunk of aluminum and lots of thermal paste gets the job done.

 

[augiedoggy]

That would be optimal but part of getting an oversized heat sink is negating the need for a fan (exterior mounted) or optimizing the fin direction for air flow. In my own experience a big chunk of aluminum and lots of thermal paste gets the job done.

Yes I agree it does.... It all depends on your budget and setup though... if you have a small controll box and dont want the heat sinks mounted externally for some reason you can always use the cheaper $3 heatsinks with a $2-3 dc fan blowing aire through your control panel which also can aid in keeping everything cool in your control panel... this is the route I took and it made it easy to mount and add another ssr. plus it mmust work well because my heatsinks dont get hot and I have the cheap fotek knockoffs from ebay.

You could also drill holes and modify a heavier pc cpu heatsink (I have a box of those floating around myself) but then things become messy with multiple ssr configurations...

 

[stickyfinger]

Is there a safe way to paint a heatsink such that heat dissipation ability is not reduced excessively?

 

[doug293cz]

Is there a safe way to paint a heatsink such that heat dissipation ability is not reduced excessively?

The paint will be an insulator between the heatsink and the air to which it is trying transfer the heat. If you must paint, then keep the paint as thin as possible. The thicker the paint the worse the heat transfer will be.

Brew on

 

[Ozarks Mountain Brewery]

I agree the surface of the heat sink dissipates the heat so if you paint over your adding insulation

 

[stickyfinger]

Do anodic films not decrease the heat dissipation? it's not a big deal, just though black would look cooler than silver. maybe i can find something online that would dissipate heat well.

 

[doug293cz]

Do anodic films not decrease the heat dissipation? it's not a big deal, just though black would look cooler than silver. maybe i can find something online that would dissipate heat well.

Anodic films are much thinner than paint, so have a correspondingly lower effect on heat sink thermal transfer to air. The thinner the coating, the less the insulating properties. Also, anodic coatings are dense aluminum oxide which has higher thermal conductivity than the organics in paint. Just buy a black anodized HS rather than painting a silver one.

Brew on

 

[stickyfinger]

ok, sounds good