Condensation concerns, cold weather issues! - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: September 14, 2014, 12:53:17 pm
content: Hello all,So, I am planning to move two servers into my garage real soon as they are incredibly loud and also very hot (they run at around 1kW total, 24/7) and the room they are in (my workroom) is getting to become unbearable. It wouldn't be much of an issue in winter (I can forgo heating that room), however, the noise issue is finally taking its toll.Therefore, I am going to build a rack and mount them in the garage outside. The garage is a brick building with no insulation. The only insulation is from the bricks. As a result, in the winter it is possible that the temperature reaches -10 deg C. Granted, it has to be very cold outside (possibly up to -20), but it is possible. Whilst this has recently not been such an issue, the possibility exists.As a result, I want to build a rack that is perhaps somewhat insulated using expanded polystyrene and perhaps have a pre-warming chamber for the air that is coming into the servers. I want to know if this is the way that it is done, or if there is any negative effect of having cold air coming into the servers? I mean, it would certainly cool the CPUs that much better, but does the possibility of condensation forming exist? Will the cold air going over the fans / cpus / heatsinks condense? Or will the fact that the fans are extracting such volume quickly not allow this to happen?What concerns are there running servers in cold weather?This is what I was thinking:

author: DanielS
author_rank: Frequent Contributor
timestamp: September 14, 2014, 02:42:57 pm
content: Since cold air can carry less moisture than hot air, I would simply blend part of the exhaust air in the fresh air stream to "pre-warm" it and reduce its relative humidity content.Since the inside of the box and components within will be well above dew point, condensation should not be an issue. You may want to use a few extra fans around your rack to make sure it heats up evenly.If you want to be absolutely sure though, you would need to use a dehumidifer.

author: Yago
author_rank: Frequent Contributor
timestamp: September 14, 2014, 03:59:45 pm
content: I would have thought the garage is the problem, the server, being a heat source may drive moisture out from the garage structure into the air.This is not a problem for the server, unless the power trips the server off and it's metalwork cools and water directly condenses on it.Insulate the garage not the server, and as said put a dehumidifier in there.IMVHO of course and disclaimer of me being a noob with a cellar!

author: Kjelt
author_rank: Super Contributor
timestamp: September 14, 2014, 05:28:00 pm
content: My non expert opinion is that I think you have no problem esp when it is freezing the air is dry.The problem is usually the other way around, hot air with normal humidity going in the vicinity of cold elements/structures. Think about a bathroom mirror, when it is heated to 40 degrees C it will not condense if you do not heat it is much colder then the warm wet air from the shower and it will condense.

author: jahonen
author_rank: Super Contributor
timestamp: September 14, 2014, 05:50:07 pm
content: Condensation will only happen if you cool down warm air below the dew point temperature. Cold air heated to higher temperature has much smaller RH% than initially.Regards,Janne

author: con-f-use
author_rank: Unknown
timestamp: September 14, 2014, 09:12:07 pm
content: Quote from: jahonen on September 14, 2014, 05:50:07 pmThis. Also condensed water from moisture contains no dissolved ions. It is essentially distilled water and thus a very good insulator. By itself it will not cause shorts. It might still cause problems in conjunctions with other contaminants, but I wouldn't worry too much.

author: tggzzz
author_rank: Super Contributor
timestamp: September 14, 2014, 09:27:03 pm
content: Quote from: trs80 on September 14, 2014, 12:53:17 pmWhat will happen when there is a power failure?

author: DanielS
author_rank: Frequent Contributor
timestamp: September 14, 2014, 11:33:21 pm
content: Quote from: tggzzz on September 14, 2014, 09:27:03 pmThe walls should cool down a fair bit faster than the servers themselves so I would expect condensation to be mostly there if there has to be any.To help that process along, it would probably help to have a small heatsink connected to exterior air to provide a cool place for internal moisture to condense on when the enclosure cools down.

author: denelec
author_rank: Regular Contributor
timestamp: September 14, 2014, 11:51:32 pm
content: I also don't think condensation will be a problem. The servers will be warmer than the garage, so no condensation should occur.But dust and insects could be problematic.I would consider adding an air filter at the intake.

author: tggzzz
author_rank: Super Contributor
timestamp: September 15, 2014, 12:07:52 am
content: Quote from: DanielS on September 14, 2014, 11:33:21 pmIt depends entirely on the temperature drop (which is dependent on temperature differential and outage duration), and humidity. Without knowing full operating conditions, it is unwise to make predictions.There are many ways of controlling condensation; we do not have enough information to determine which are practical. Sure we can have a hopeful guess, but the OP might like a stronger assurance!QuoteMaybe maybe not; depends on geometry and (fanless) airflow.

author: Whales
author_rank: Super Contributor
timestamp: September 15, 2014, 02:27:49 am
content: You could try a dual-air (heat exchanger) system. Pipe the exhaust air through a car radiator that is mounted outside, and take the air back through to the server intake. Mount a large fan on the radiator. It should handle more than a kW of heat, even though you're cooling air rather than fluid.Cons: large and needs piping.

author: abaxas
author_rank: Regular Contributor
timestamp: September 15, 2014, 12:05:20 pm
content: 1kw is going to warm up any garage!Stick the servers in there and forget about them.

author: rdl
author_rank: Super Contributor
timestamp: September 15, 2014, 12:27:34 pm
content: Just curious, but why do you even have such computers in your home? Incredibly loud? Very hot? Sounds like something from the 90s. I have a server for movies, music and backups that has 6 TB of storage and idles at 35 watts when the disks aren't spinning. Even when it's working I can barely hear it from 10 feet away. I guess you must have some unique needs.

author: made2hack
author_rank: Frequent Contributor
timestamp: September 15, 2014, 01:43:14 pm
content: @rdl = bitcoin miners, running at over 1kW.As for the bugs and dust, I will have filters on the incoming air so as not to allow much more than air to come in.I never thought about condensation as hot air over a cold surface, but that does make sense of course, now that I think of it.It's in the summer when you have a cold drink that the outside of the glass gets condensed. Winter cold air is quite dry, all the water around is frozen.Thanks all I will take into consideration what I've learned, and make sure that the case is well insulated and ventilated.

author: G7PSK
author_rank: Super Contributor
timestamp: September 15, 2014, 02:39:29 pm
content: You don't get condensation going from hot to cold it's the other way around ( which is why your glasses get steamed up when coming in from the cold not when you go out). So as the server will always be warmer than the surrounds you won't get condensation on it, even if the power went down it would still be warmer than the air for a long time.

author: DanielS
author_rank: Frequent Contributor
timestamp: September 15, 2014, 03:14:14 pm
content: Quote from: G7PSK on September 15, 2014, 02:39:29 pmCondensation can form wherever high-humidity air meets colder air or surfaces if the temperature transition crosses dew point... like breath in winter or opening a freezer on a steamy hot day.If the humidity content within the hot box is high enough to cross dew point as the box cools down, there will be condensation inside the box, mostly around the coldest points. Extra measures may be necessary to ensure those coldest points are away from anything sensitive to condensation or potential dripping.

author: tggzzz
author_rank: Super Contributor
timestamp: September 15, 2014, 03:27:17 pm
content: Quote from: trs80 on September 15, 2014, 01:43:14 pmAround here winter air is cold and damp - and repeated transitions above<->below freezing are the problem.Ventilation a key to controlling condensation, unless the incoming air is near its dew point.

author: G7PSK
author_rank: Super Contributor
timestamp: September 15, 2014, 04:19:32 pm
content: Quote from: DanielS on September 15, 2014, 03:14:14 pmWe are talking about condensation onto surfaces here not injecting hot moist air into cold air. Move a warm surface into cold air and you do not get condensation on it go the other way and you will. That's why the rear windows and some front as well have electric heating elements in them.

author: DanielS
author_rank: Frequent Contributor
timestamp: September 15, 2014, 08:58:42 pm
content: Quote from: G7PSK on September 15, 2014, 04:19:32 pmIt is not just surfaces you need to worry about but the air as well: if the hot air inside the box somehow manages to accumulate enough total humidity and a blast of frigid air comes in, relative humidity shoots past 100%, air inside the box will fog and you will end up with condensation even on warm surfaces until internal temperature goes back up high enough to carry the excess moisture.

author: VK5RC
author_rank: Unknown
timestamp: September 15, 2014, 11:44:02 pm
content: I would try to harness back some of that energy esp for heating your house in winter 1kW 24/7 is a lot of energy to throw away!

author: ConKbot
author_rank: Super Contributor
timestamp: September 16, 2014, 10:25:56 am
content: Quote from: DanielS on September 15, 2014, 08:58:42 pmSounds like the answer here is to not put it in a box thats sealed up. Just put them in the garage, no covers, just a ventilated rack if youre feeling fancy. Even in a cold shed, at 1kW draw, they are going to need to be ventilated, and not put in the shed.And +1 to VK5RC. 1kW is ~3500BTU/hr IIRC. 1kW will go surprisingly far. Do you actually put cars in your garage? just keep stuff in it? Would it be objectionable to vent the servers (dryer duct from fan exhausts? ) back into the house. I wouldnt if you actually have cars go in the garage or it reeks of a gas can in there from mowers or other small engine'd tools/toys

author: made2hack
author_rank: Frequent Contributor
timestamp: September 18, 2014, 12:09:20 pm
content: No cars, or gas stuff, however a whole bunch of junk.Initially, the idea was to use it in my basement / downstairs room so that I wouldn't need to heat it during the winter.However, the noise problem is big, plus, it currently warms the room to around 32 - 35 deg C (which is approx 10 deg higher than ambient). Now, in winter, that room generally drops down to about 17 - 18 without warming it up, so, with the servers, it would still get it warmed to around 27 - 28 in winter, waaaay to high.As for the exhaust coming back into the house, I would have to insulate the duct for the length of about 5 meters from the garage back into the house. I'm not sure whether that is feasible, or whether the loss would be too great.I do agree that I am "wasting" a whole bunch of potential heat, and I hate that, but, don't know what I can do, unless I maybe plant some tomatoes and maybe some peppers and cucumbers in the garage over winter, and throw in some lights to see whether they can grow (now that it will be warm).

author: Clear as mud
author_rank: Regular Contributor
timestamp: September 19, 2014, 02:23:58 am
content: In my computer, one of the fans gets stuck, makes noise, and draws too much current when it is cold. You should at least check on the computers when the temperature is cold, and make sure something like that isn't happening.

author: made2hack
author_rank: Frequent Contributor
timestamp: September 23, 2014, 08:22:51 am
content: @wilfred, As I had replied earlier, they are not "servers" in the traditional sense, they are bitminers which run @ full power 24/7

author: mikerj
author_rank: Super Contributor
timestamp: September 23, 2014, 11:03:48 am
content: Quote from: abaxas on September 15, 2014, 12:05:20 pmAny garage that sealed well enough for their to be no draughts and with some thermal insulation. 1kw wouldn't make any noticeable difference to temperature in my draughty workshop.

author: made2hack
author_rank: Frequent Contributor
timestamp: September 23, 2014, 11:24:14 am
content: @Wilfred,I suppose it is a matter of how much hashing power and what your costs are. At the moment, the setup generates on the order of approximately 250Euros/Month. Electricity costs some 70 Euros / Month.I estimate the revenue will drop 10 - 15 / month until it will no longer be profitable (ie cost = revenue) at which point, either I will have to increase hashing power or stop mining.Now, if the price of BTC rises, then it becomes more profitable in the short run, or I can go on longer. If the price of BTC drops, it may end up being unprofitable tomorrow. Don't really know. I am hoping to manage this way until I recoup costs (10 - 12 months).Now, I am looking to develop my own boards with some hashing CPUs, however, I don't know much about CPU logic. Some manufacturers do provide some schematics after you sign an NDA agreement, but I hate that I have to buy a bunch of chips just to get started.Maybe someone on the forum has some experience in building a hashing unit from scratch (using existing ASICS).