Heatsink question

awarner322 · Jun 1, 2013

Hey guys, I am struggling with the idea of a heat sink. I am having an electrical engineer buddy put together my control panel for me. It is a 50a 2 element 2 PID system (basically this PJ wiring diagram).

My question now is...what type/size of heat sink do you suggest I get? Do I also need a fan? Does the heat sink need to be mounted internally? or a hole cut in box?

Thanks in advance!

jeffmeh · Jun 1, 2013

I favor externally mounted heat sinks. You would need to cut the panel and mate the SSRs to the heat sink(s) with thermal compound. If you oversize the SSRs for the elements (e.g., use 40a instead of 25a for a 5500w element), and go with a heat sink to match, you shouldn't have any problems.

You could go with this one: http://www.theelectricbrewery.com/custom-heat-sink

Also, take a look at http://www.heatsinkusa.com/

awarner322 · Jun 1, 2013

Ok, so excuse my ignorance....but the sink needs to be attached to the SSRs?

danb35 · Jun 1, 2013

Yes. The purpose of the heat sink is to dissipate heat from the SSRs.

Dawai · Jun 2, 2013

"this I can help with", I'm a old electrician.

Mass of finned aluminum for a heat sink, anodized so it will not corrode, Milled flat AND heat sink grease to conduct the heat. You still need air circulated around it.

OTHERWISE you have a bumpy surface that does not make contact, and no true heat exchange. Most heat sinks are for show and "false" confidence. A piece of copper sheet helps with transfer also, but is rarely done. (do you really need it?)

You can mill a item flat by taking a piece of glass and sandpaper, glass is normally flat, hit the high spots, I've done numerous gasket surfaces over the years like this.

you can anodize in a 5 gallon bucket with dc electricity. I've done it with a dc welder here.

You can purchase heat sinks off ebay, or any good electronic supply. I've mounted Gecko drives on heatsinks with fans.

jeffmeh · Jun 2, 2013

Dawai said:
"this I can help with", I'm a old electrician.

Mass of finned aluminum for a heat sink, anodized so it will not corrode, Milled flat AND heat sink grease to conduct the heat. You still need air circulated around it.

There are many control panel builds with external heat sinks that rely on ambient air for cooling, with no fans, and no problems.