SSR and heatsink inside enclosure?

[WI_Wino]

I'm in the (slow) process of building a simple control panel for my setup (15 gallon BIAB). I have some large industrial grade all metal enclosures laying around and I intend to use one. Dimensions are 18" X 28" X 8". Panel would live in my basement, ambient temps range from 50F-72F.

Panel overview:

30A 240V GFI protected 4 wire service

1 - 40A Fotek SSR (I am ok replacing this if a different SSR generates less heat)
1 - 5500 W SS element
1 - myPin TD4 PID
1 - 15 A outlet and switch for pump
4 - LED panel lights (main power, pump light, element light, alarm LED/buzzer)

Power disconnect will be probably handled outside the panel, maybe i'll add a switch and contactor. I might have one for the pump circuit as well, depends if I want to use a panel switch rated at 10 A vs. a light switch at 15-20 A.

Questions:
- With that much open volume in the panel, can I mount the SSR and heat sink inside the enclosure rather than cutting a hole?

- Can I skip cutting a big hole and mount the SSR on the inside and the heat sink directly on the other side of the enclosure?

- (probably the worst idea) can I direct mount the SSR to the enclosure since it is all metal and not use a heat sink?

 

[golfindia]

At 1-1.5 Watts per amp, that ssr will be putting out around 30w-ish.

I'd put it on the outside.

 

[-CHRIS-]

I tried mounting my Fotek SSRs inside my cabinet and kept melting them. I then bought a massive heatsink from eBay and mounted it to the outside of the cabinet and haven't had a problem since. The included heatsinks could probably work if you can get a fan to blow cooling air across them.

Chris

 

[doug293cz]

You could probably get by with mounting the SSR to the inside of the box, and the heatsink immediately opposite on the outside of the box. Any paint on the box would need to be removed from both the inside and outside mounting points. Place heatsink thermal compound between the SSR and box, and the HS and box. SSR should be cool enough to hold on to while in operation. Best to measure the SSR temp with an infrared thermometer.

Mounting everything inside the box is not a good idea unless you have forced airflow (fan) thru the box (not just recirc inside the box.)

Brew on

 

[FuzzeWuzze]

Doug got most of it, but you'll definately want a main power kill switch and pump switches to turn them on off. The amp rating of the switch shouldnt really matter because you shouldnt be letting that much current through there anyways, its a safety hazard, they should be used to control contactors that have very small current draw to open/close them.

 

[doug293cz]

Doug got most of it, but you'll definately want a main power kill switch and pump switches to turn them on off. The amp rating of the switch shouldnt really matter because you shouldnt be letting that much current through there anyways, its a safety hazard, they should be used to control contactors that have very small current draw to open/close them.

I agree a panel needs to have proper isolation switching to provide positive shut off for any circuits with dangerous voltage levels. I was just addressing the thermal management in my earlier reply.

Brew on

 

[WI_Wino]

Saying a contactor is required for pumps pulling at most 15 amps at startup seems like overkill. Every day you turn on lights and run appliances such as garbage disposals via switches and no one dies.

 

[FuzzeWuzze]

Saying a contactor is required for pumps pulling at most 15 amps at startup seems like overkill. Every day you turn on lights and run appliances such as garbage disposals via switches and no one dies.

I only meant for the 2 primary hot legs, which would also kill the pumps if needed. His build has no mention of a primary contactor/switches which leads me to believe hes just powering it on/off by plugging/unplugging the entire box from the wall..which isn't really a safe solution.

 

[WI_Wino]

I only meant for the 2 primary hot legs, which would also kill the pumps if needed. His build has no mention of a primary contactor/switches which leads me to believe hes just powering it on/off by plugging/unplugging the entire box from the wall..which isn't really a safe solution.

That's not what I meant in my original post. There will be a disconnect of some sort, definitely not relying on the plug. I'm not sure if it'll be in the panel itself or outside of it though.

 

[atoughram]

You could probably get by with mounting the SSR to the inside of the box, and the heatsink immediately opposite on the outside of the box. Any paint on the box would need to be removed from both the inside and outside mounting points. Place heatsink thermal compound between the SSR and box, and the HS and box. SSR should be cool enough to hold on to while in operation. Best to measure the SSR temp with an infrared thermometer.

Mounting everything inside the box is not a good idea unless you have forced airflow (fan) thru the box (not just recirc inside the box.)

Brew on

This works for me - I've got thermal grease inside and out.

 

[MrShake]

I will second that that heatsink needs to be outside the box!! As well, where did you get your SSR? A BUNCH (read most) of the SSRs on Amazon are knock-offs that will NOT handle your 5500watt element well and will produce a ton of heat, even with the sink on the outside. Just something to be aware of.

 

[BrunDog]

I would think that if you put a fan on your heatsink to strip off the heat locally, and the combo were inside a large enough metal box, the box would effectively sink the heat to the atmosphere, assuming it is not exposed to direct sun. The fan becomes a failure point, but the worse thing that happens is the SSR dies during a brew. I don't think it would be a fire hazard.

Anyway, you could try it. It may work just fine. But, at the end of the day the passive solution of the external heatsink that has been in use by many has proven its worth. You may wonder if its worth bucking the trend.

 

[stevehaun]

I have a 20 X 16 X 8 enclosure with a 50 amp system. I have two crydom heat sinks attached directly to the back plate of the enclosure. I have two crydom SSRs (40 amp). I run two 4500 watt elements simultaneously for the entire brewday (2 elements in HLT and 2 elements in BK). I have been brewing for over 9 years on this system and I am still using the original SSRs.

I don't understand why so many electric brewers have problems with their SSRs overheating.
Control panel too small?
Inadequate heat sink?
Crappy SSRs?

To the original poster, with an enclosure that large you should have no problems with your SSR overheating if you use a reasonable heat sink. Attach the heat sink to the back panel which will serve as an additional heat sink.

 

[MrShake]

I have a 20 X 16 X 8 enclosure with a 50 amp system. I have two crydom heat sinks attached directly to the back plate of the enclosure. I have two crydom SSRs (40 amp). I run two 4500 watt elements simultaneously for the entire brewday (2 elements in HLT and 2 elements in BK). I have been brewing for over 9 years on this system and I am still using the original SSRs.

I don't understand why so many electric brewers have problems with their SSRs overheating.
Control panel too small?
Inadequate heat sink?
Crappy SSRs?

To the original poster, with an enclosure that large you should have no problems with your SSR overheating if you use a reasonable heat sink. Attach the heat sink to the back panel which will serve as an additional heat sink.

a LOT of it is knockoff SSRs. As well, lots of guys have used and do us plastic enclosures.. causing issues. Metal is a much better solution!

 

[atoughram]

I've got one ssvr that is mounted inside a box on a heatsink. In that installation, I've got forced ventilation on the box. and it puts out some fairly warm air.

 

[UndeadFred]

It is a little noisy, but compact. I use a 120V "boxer" fan and an e-bay heatsink, and heatsink compound on my SSR, mounted inside the box but with a intake and exhaust port. The PID I mounted outside of the box and just insulated the contacts with a little plastic piece I fabricated up. In my case I used old parts I already had and added a second e-bay heatsink and a SSVR in series so I use both. It was cheaper than a new PID for me... But that "blower" arrangement I can run for hours and the SSR and SSVR in the box don't really get above ambient. I like that I can also hear that the box is on ....

I should add that my SSR is a 40A "Fotek" so likely a knockoff as well.. but it's 100% reliable in the setup run for many hours now.

 

[golfindia]

The 40a SSRs should have a bigger heat sink than 25a. Auber has 2 different sizes. I've bought 40a Fotek SSRs from amazon and they included the small heatsink. This is my guess as to why they fail so often.