Heat sink - wall mount vs offset for better heat dissipation

[Stewfish]

So I have a new 100 amp solar charge controller and it's the epever with a huge heat sink on the back. if I use the mounting holes then the heat sink will be about a half inch off the wood board. I'm just wondering if I offset that and say put a 2x4 in there between the wall and the mounting bracket and have 1.5" away from the wall will I get better heat dissipation. If I.am off the wall more than a PC fan would fit better on top. Is it engineered to be close to the wall and that creates more air flow as the heat rises? I'm just debating how I should Mount this even though they clearly have it mounted close to the wall. just wondering if there's engineering involved if I mount it on some 2x4s then I will probably have enough room to put a computer fan or two on top to pull air upwards. Let me know your thoughts, pardon my voice to text grammar

 

[Q-Dog]

I would assUme the heat sink is engineered for the mounting space that is built into the inverter. Given that assumption, I have thought about mounting the controller to a metal sheet and spacing the sheet from the wall to give the sheet some cooling space away from the wall. Kinda like a heat shield on a muffler or exhaust pipe on a car.

It is also possible I am giving the inverter designers more credit than they deserve.

 

[cinergi]

If your ambient temperatures are going to be less than, say, 85F I wouldn't give it a second thought (including not employing a fan). Will you be maxing it out (all 100 amps)?

 

[snoobler]

No harm in anything you're proposing. The heat sink is presumably designed to be sufficient with the installed clearance, and the maximum recommended operating temperature of the unit. Improving convective and radiant heat transfer characteristics will do no harm. Most important is to follow any installation clearance requirements.

I would personally not consider sheet metal as a backing as that's a potential radiant barrier and could easily reflect heat back at the unit rather than dissipate it.

If I was pursuing your goals, I would consider:

1. Ensure nothing is heating the "intake" air below the unit.
2. Install the pan to push air up. Sucking hot air vs blowing cool air would reduce the life of the fan.

 

[Stewfish]

I would assUme the heat sink is engineered for the mounting space that is built into the inverter. Given that assumption, I have thought about mounting the controller to a metal sheet and spacing the sheet from the wall to give the sheet some cooling space away from the wall. Kinda like a heat shield on a muffler or exhaust pipe on a car.

It is also possible I am giving the inverter designers more credit than they deserve.

True, I was also wondering if I was giving the engineers too much credit. It was probably just easier to combine the mount and heat sink like they did vs putting the heat sink on the front away from the wall.

 

[Stewfish]

No harm in anything you're proposing. The heat sink is presumably designed to be sufficient with the installed clearance, and the maximum recommended operating temperature of the unit. Improving convective and radiant heat transfer characteristics will do no harm. Most important is to follow any installation clearance requirements.

I would personally not consider sheet metal as a backing as that's a potential radiant barrier and could easily reflect heat back at the unit rather than dissipate it.

If I was pursuing your goals, I would consider:

1. Ensure nothing is heating the "intake" air below the unit.
2. Install the pan to push air up. Sucking hot air vs blowing cool air would reduce the life of the fan.

Good points

 

[Q-Dog]

No harm in anything you're proposing. The heat sink is presumably designed to be sufficient with the installed clearance, and the maximum recommended operating temperature of the unit. Improving convective and radiant heat transfer characteristics will do no harm. Most important is to follow any installation clearance requirements.

I would personally not consider sheet metal as a backing as that's a potential radiant barrier and could easily reflect heat back at the unit rather than dissipate it.

If I was pursuing your goals, I would consider:

1. Ensure nothing is heating the "intake" air below the unit.
2. Install the pan to push air up. Sucking hot air vs blowing cool air would reduce the life of the fan.

I don't really want the wood backing to absorb any heat. A light coat of flat black on the metal sheet, the side facing the heat source, should reduce potential to radiate any heat back to the inverter. The space behind the sheet should give a path to dissipate more heat rather than letting the wood absorb it.

Yes, I am somewhat concerned with mounting these things directly to a wood backing. I recall a conversation about one unit that says not to mount to a flammable surface. I can't find that right now, but it did make me think.

 

[Stewfish]

Aluminum

I don't really want the wood backing to absorb any heat. A light coat of flat black on the metal sheet, the side facing the heat source, should reduce potential to radiate any heat back to the inverter. The space behind the sheet should give a path to dissipate more heat rather than letting the wood absorb it.

Yes, I am somewhat concerned with mounting these things directly to a wood backing. I recall a conversation about one unit that says not to mount to a flammable surface. I can't find that right now, but it did make me think.

Aluminum sheeting would probably work good for heat dissipation

 

[snoobler]

True, I was also wondering if I was giving the engineers too much credit. It was probably just easier to combine the mount and heat sink like they did vs putting the heat sink on the front away from the wall.

It's possible to give engineers too much credit, but one has to assume it was designed to meet the specifications. No harm in trying to enhance performance with a sensible approach.

I don't really want the wood backing to absorb any heat. A light coat of flat black on the metal sheet, the side facing the heat source, should reduce potential to radiate any heat back to the inverter. The space behind the sheet should give a path to dissipate more heat rather than letting the wood absorb it.

Yes, I am somewhat concerned with mounting these things directly to a wood backing. I recall a conversation about one unit that says not to mount to a flammable surface. I can't find that right now, but it did make me think.

Black objects radiate more heat. Most radiant fins are black for this reason. Painting the sheet metal black would enhance the tendency to reflect the heat back to the unit.

NFPA code compliance prohibits mounting to a flammable surface, thus it makes sense the manufacturer would instruct you to not mount to a flammable surface. This is often addressed by a $75 gallon of fire resistant paint from Home Depot/Lowes applied to the plywood. That's what I'm doing.

 

[Stewfish]

It's possible to give engineers too much credit, but one has to assume it was designed to meet the specifications. No harm in trying to enhance performance with a sensible approach.



Black objects radiate more heat. Most radiant fins are black for this reason. Painting the sheet metal black would enhance the tendency to reflect the heat back to the unit.

NFPA code compliance prohibits mounting to a flammable surface, thus it makes sense the manufacturer would instruct you to not mount to a flammable surface. This is often addressed by a $75 gallon of fire resistant paint from Home Depot/Lowes applied to the plywood. That's what I'm doing.

Hardy board or cement board would be good too.

 

[Hedges]

It's possible to give engineers too much credit, but one has to assume it was designed to meet the specifications. No harm in trying to enhance performance with a sensible approach.

Black objects radiate more heat. Most radiant fins are black for this reason. Painting the sheet metal black would enhance the tendency to reflect the heat back to the unit.

As is the case in all fields, some engineers are incompetent, and some are astute.
There are stories of unfortunate technical decisions being deliberately maintained for decades, due to business considerations.
Not uncommon for one out of thousands/millions of consumers to outthink the handful of company engineers and find a better way.
The least we hope for is a product that meets specifications. Quite often it does not.

Black radiates more, but it also absorbs more.
A black heated object nearby would shine more IR on your heatsink.
A black sheet of metal nearby would absorb more IR from your heatsink. It would then radiate back only some of that heat, and would also conduct away some of the energy.
A shiny metal sheet would reflect most IR back at the source.

So my money is on a black aluminum sheet being a better neighbor than a shiny aluminum sheet.

For long wavelengths of IR, a shiny metal surface will have specular reflection. If you made a 90 degree "V" of reflective metal and mounted it between heatsink and wall, then any IR that landed on it would be reflected away at same angle as incidence but in opposite direction (mirrored across an orthogonal line.) That should deflect IR away from the heatsink. (depending on spacing, because IR coming from surface of heatsink will radiate in all directions.)

I would consider playing with convection. Mount a chimney above the heatsink, so rising hot air holds together and makes a higher velocity draft. Consider how an oil lamp behaves when the glass is placed over it.

 

[MattiFin]

Convection cooling is dominating at low temps so I woudn’t worry too much about adjacent object emissivity or color.

 

[HRTKD]

Hardy board or cement board would be good too.

While that type of material is very good at managing heat, I would be reluctant to install my components on it due to the dust. All the Hardie Backer Board I've ever used was installed behind something else, like tile. Their MSDS says that all the health warnings apply to manipulation of the product. A sheet of Hardie Board mounted on a wall shouldn't produce much dust.

 

[Stewfish]

As is the case in all fields, some engineers are incompetent, and some are astute.
There are stories of unfortunate technical decisions being deliberately maintained for decades, due to business considerations.
Not uncommon for one out of thousands/millions of consumers to outthink the handful of company engineers and find a better way.
The least we hope for is a product that meets specifications. Quite often it does not.

Black radiates more, but it also absorbs more.
A black heated object nearby would shine more IR on your heatsink.
A black sheet of metal nearby would absorb more IR from your heatsink. It would then radiate back only some of that heat, and would also conduct away some of the energy.
A shiny metal sheet would reflect most IR back at the source.

So my money is on a black aluminum sheet being a better neighbor than a shiny aluminum sheet.

For long wavelengths of IR, a shiny metal surface will have specular reflection. If you made a 90 degree "V" of reflective metal and mounted it between heatsink and wall, then any IR that landed on it would be reflected away at same angle as incidence but in opposite direction (mirrored across an orthogonal line.) That should deflect IR away from the heatsink. (depending on spacing, because IR coming from surface of heatsink will radiate in all directions.)

I would consider playing with convection. Mount a chimney above the heatsink, so rising hot air holds together and makes a higher velocity draft. Consider how an oil lamp behaves when the glass is placed over it.

I also thought aluminum would be great. Turns out I had some 1.5" x 1.5" square aluminum tubing lying right next to the battery compartment that gave me an idea. I cut, drilled and bolted the tubing to the unit. I then drilled and screwed the tubing to the wall in my 5th wheels' battery compartment/ basement which is steel over plywood. Its not a good as aluminum sheet but will work fine. Now I can add fans if I want.

 

[Whinny]

If the controller is mounted closer to the wall the "chimney effect" would probably create greater airflow over the heatsink

 

[evilroy]

If you want to check air flow just do a simple smoke test, 1/2 inch from the wall should create good draft and further from the wall you move from moving the air to radiating, an aluminum back panel will help reduce heat penetration into the surrounding area, even aluminum foil works good but chances are you already have a 1/2 inch thick sheetrock which should be plenty in itself, if wood yes you want a barrier all depends on how hot your heat sink is getting, regardless will be fun to find out.

 

[mmtech]

I have two of these controllers mounted about a inch from the surface with spacers you can get at home depot and a computer fan hooked to the load output. In the summer if i see the output is high i turn the fan on remotely. controller actually runs cold.