Max ambient temperature for a miner

[cdtbtc]

Is there a maximum recommended ambient temperature for a scrypt miner like the A2? I'm having trouble finding this from any official sources, so I welcome any constructive feedback you may have to offer.

[Borisz]

I found this relating to another bitcoin miner, just for reference.

S3 Specs

Effective Hash Rate: 504 GH/s±5%
Power Consumption: 390 W on wall
Power Supply: 4 +12V DC input, PCI-e connectors
Power Efficiency: 0.77 J/GH on wall
Size: 331 mm x 137 mm x 160 mm (Dual blades assembled inside a box, including the fans)
Fans: Two 14038 fans mounted on both front and back ends.)
Operating Temperature: 0 °C to 35 °C
Complied with: FCC / CE
Network Connection: Ethernet

source

So I'm guessing it is probably the same for most miners.

You can also check out http://www.usbminers.nl/Innosilicon_A2_PG_v120140424.pdf

Also found this more related to your miner,

The three big cooling fans push air inside the case thorough the large aluminum heatsinks and the hottest temperature we’ve measured was just at about 42 degrees Celsius. This is with an ambient temperature of 25 degrees C, so there could be some variance and you should be careful not to place the miner in hot areas without good ventilation.

source

I think there is no strict limit, they maybe haven't tested it. Perhaps you can send an email to enquire or make an experiment and check how hot the miner gets and what has rate it produces.
Don't forget to share the results!

[Grout]

Also, there is a direct correlation between the ambient temperature and temperature of the hardware you are trying to cool:
If your hardware runs at 45°C in a 20°C room, it will be at 55°C in a 30°C room.
Isn't physics cool?

[cdtbtc]

Thanks, Borisz. I did find those posts, but I took that to mean that it's the temperature that the chip itself runs at if the rig is at normal room temperature.

Grout makes a very interesting point about the correlation between the two temperatures, and I guess I suspected as much. One seller was saying "Well, the operating temperature is 40-50C, and even in the summer, garages won't get that hot, so you should be good". But if Grout is correct, and it would makes sense that he/she is, then the seller either doesn't know what they're talking about or they're just blowing smoke up my ass.

Still though others have rigs in garages, right?

[Borisz]

Thanks, Borisz. I did find those posts, but I took that to mean that it's the temperature that the chip itself runs at if the rig is at normal room temperature.

Grout makes a very interesting point about the correlation between the two temperatures, and I guess I suspected as much. One seller was saying "Well, the operating temperature is 40-50C, and even in the summer, garages won't get that hot, so you should be good". But if Grout is correct, and it would makes sense that he/she is, then the seller either doesn't know what they're talking about or they're just blowing smoke up my ass.

Still though others have rigs in garages, right?

Ok, well I guess a lot of seller are just re-sellers and not actual manufacturers of equipment. Hence they don't know the exact specs. I was always wondering why there is no information given about operating conditions, normally it has to be given for every electronic product. Not even manufacturers give this info sometimes, however they were ought to test it! Just to set it clear,

ambient temperature = air temperature of the space where the miner is
operating temperature = temperature to which the miner heats when operated (this can be surface or chip etc. temperatue, depends where the manufacturer measures, if at all)

And of course there is a pretty much direct correlation between ambient and operating temperature, although it depends on other factors as well e.g. airflow, I thought this was clear from the start.

I am not even running my desktop  PC much when temperatures are close to 40C and I would advice against running a miner under such conditions. As per the previously mentioned article says, the miner heats to about 42C if the room is at 25C. This is kind of a normal operating condition for electronics. It is probably safe to go until 35C, just like with an S3, however higher temperatures will lead to failures more likely.

Alternatively you can increase the air flow to cool the miner better. Where are you trying to operate it? Don't you have e.g. a basement or something similar?

[cdtbtc]

By contrast, I run my computer regardless of the temperature in the house, although I rarely let it get hotter than about 27C before turning on the AC.

The plan for this miner is to actually keep it at a friend's house while I am abroad. I plan to monitor it remotely, and my friend is tech savvy in case hands-on maintenance is needed. He doesn't have a basement though, and I'm concerned that if I run an A2 in his spare bedroom, for example, that the noise will be a nuisance. Whereas if it were in the garage, it would be much more separated from the rest of the living space. I supposed I might be able to install a window-mounted AC unit in his garage, although I'd have to run some numbers in terms of how efficient that'd be.

Regarding increased air flow, correct me if I'm wrong, but it seems as though, even if you have the thing in an air tunnel, if the ambient temperature is 38C, the components won't ever get cooler than 38C.

The manual you linked to does give a max junction temperature of 60C, and says "It is advised that the cooling design should be conservative to maintain surface heat sink temperature less than 48 degree under fan cooling for the best chip performance." It doesn't really give any specifics as to the ambient temperature, but that's pretty close.

It goes on to say "Appropriate dissipation through ground vias should be engineered in order to transfer the heat from the bottom pad to the bottom layer of the PCB board where an aluminum heat sink should be placed, " which sure sounds like they want you to engineer your own heat dissipation, which I thought was odd.

Anyway, I'll drop them an email, and see if they can clarify or give any recommendations.

[Borisz]

Regarding increased air flow, correct me if I'm wrong, but it seems as though, even if you have the thing in an air tunnel, if the ambient temperature is 38C, the components won't ever get cooler than 38C.

Yes that is correct, you cannot cool it down further than the temperature of the medium you are cooling it with. However, following your example and assuming that you are cooling it with 38C air with an air flow of X litres/minute. Let's say that the junction temperature goes up to 55C, which is then 7 degrees C higher than the recommended temperature during operation. By using the same ambient temperature air, but doubling the flow rate you could cool it down further, possibly reaching the safe limit of 47C. Hence it is about increasing the rate of heat transfer from the miner to the ambient air.

It goes on to say "Appropriate dissipation through ground vias should be engineered in order to transfer the heat from the bottom pad to the bottom layer of the PCB board where an aluminum heat sink should be placed, " which sure sounds like they want you to engineer your own heat dissipation, which I thought was odd.

If this is the case, then it might be worth looking into a new heatsink with better overall efficiency as opposed to an AC unit. Surely, bilding your own would be a lot of work and hassle, perhaps an off the shelf approach would be best. Although I agree, it is odd that they tell you to continue building your product 

Best thing to do is ask them if they have tested it. Maybe they can also give you some advice what else could you do.

Good luck with your project!! (You can let me know if you need help crunching some numbers)

[cdtbtc]

Good luck with your project!! (You can let me know if you need help crunching some numbers)

Thank you! I just sent them an email this morning, so I'll post their reply and my results here once I get more information.