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Topic # 127228 3-Aug-2013 09:55
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Due to limited space in my very old house, and the need for things like UFB termination equipment, router (8 port residential), and Wifi, plus who knows what else in future (AV equipment perhaps) I'm considering building a vented rack/cabinet in my ceiling. The ceiling is quite dusty, gets cold in winter, and hot in summer.

The general idea is build a wooden cabinet to hold equipment, maybe half a meter on each side. I don't think I'll actually build racks, just something that will keep dust out, with filtered vents (light fabric) in the bottom and top to let warm air out by convection. To deal with hot weather I'd get an extractor from a hardware store which would take air from outside the house and blow it into the cabinet at a low but steady rate, from the bottom on the side.

After checking equipment specs most should operate fine in 30 degrees heat, if vented, and most will work to 40 degrees. Since the outside temperate rarely gets near 30 degrees in Wellington that should solve the temperature issue.

Can anyone think of anything I've missed? Any way to do things better? Should I just build a box, a box with some shelves, or should I put some kind of commercial rack up there? "Put it in the body of the house" wouldn't be a useful suggestion at this point.

Thoughts and ideas appreciated :)




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  Reply # 871107 3-Aug-2013 10:07
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I suspect ventilation/temperature will be the biggest hurdle - roof spaces can get far hotter in summer than ambient temp, and it would take careful planning to get the ventilation sorted to keep the temp down.

Bear in mind that the higher the operating temp of equipment, the shorter the lifespan - it's not a hard (say 30 degree) limit that's go / no go, but a sliding scale. Anything you can do to drop the temp a couple of degrees lower will have a positive impact on lifespan.

I doubt the ambient temp in Wellington would drop low enough to have any significant impact, so keeping cool would be the issue...



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  Reply # 871197 3-Aug-2013 13:43
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That's what the extractor is for RM. It wouldn't run as an extractor though, it would be used to pump cool outside air into the cabinet - like Google/Microsoft do in their data centers near the arctic.

Good point re lifespan, but honestly I can afford to replace a router every few years, and if they do go regularly I'll just have to find somewhere inside.

Of course I could put the cabinet under the floor as well... it's cooler there, but it's dirt floor and cats could possible pee on it - despite my best efforts to keep them out.




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  Reply # 871238 3-Aug-2013 15:30
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You will need to do regular maintenance of filters on the ventilation hose. See if you can get everything running off 12V DC, then get a quality single 12V power supply for all equipment. Most likely a din rail mounted power supply will be good, and Mean Well is a great brand. They are adjustable, so set it to 13.8V (actually need slight compensation for temperature, can;t remember details right now) and keep a battery charged so you do not rely on mains power and your equipment is protected from surges. Household power adapters will not last in a ceiling, equipment will be mostly okay as long as it does not get too hot.




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  Reply # 871239 3-Aug-2013 15:38
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I hadn't thought about filters on the incoming air. I guess another piece of cloth on the hose input to the cabinet.

Why won't regular power supplies work up there, given I'll keep it reasonably cool? If it's as simple as just buying some special power supply that will plug into all the equipment great, but every piece of equipment tends to have a different type of connector. TBH I'd probably use mains power, a surge protector, and regular power supplies, if it fails then I'd look at replacing it.




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  Reply # 871446 3-Aug-2013 23:01
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Regular supplies will work, but they are the first things to fail. It will be intermittent and output noisy ("dirty") DC rather than a definitive fail so it will actually stress your equipment long before you find out the power supply is faulty. The generic ITE power supplies cost about $5 to the manufacturer, it is not a quality part designed by the equipment manufacturer. A DIN rail power supply on the other hand is designed to be hard wired to your mains supply so is designed to last longer by using quality parts.

Consumer surge protectors serve no purpose other than a comfort feeling and making the stores lots of money. They are too slow, the spark gaps in your light/power switches will arc over before the surge protector can react. All electrical products get tested to handle typical surges that occur in household environments. The thing that damages your equipment is brownouts where the equipment operates in an undefined state. Or dried out bulk electrolytic capacitors.




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  Reply # 871490 4-Aug-2013 08:39
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If the cooler air coming from outside meets the warm air in the ceiling space,the condensation could really hurt.

Are you sure you can't put a cabinet high on the wall somewhere in the house?

Also, restarting routers/modems when they need it can get tiresome if you have to go into the roof

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  Reply # 871513 4-Aug-2013 09:59
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mthand: If the cooler air coming from outside meets the warm air in the ceiling space,the condensation could really hurt.



Are you sure you can't put a cabinet high on the wall somewhere in the house?



Also, restarting routers/modems when they need it can get tiresome if you have to go into the roof


I use the top shelf in our linen cupboard which doesn't go to the ceiling, I can sit wifi APs on top out of the eyeline.

Jon



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  Reply # 871528 4-Aug-2013 11:02
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Condensation is a good point. Since there's a thermostat the differential should be no more than ten degrees, probably less as it will come on as soon as there's a one degree differential. That should minimise it.

I do have a plan to put the equipment into the top of a wardrobe, once I have a spare $10K to get the wardrobes built. That will have less ventilation though. All of our cupboards are full, though there's a chance I may be able to make a little room in one of them - it will be a bit tight though, not great for ventilation.

Niel, can you explain why the power supplies will have more problems in the ceiling cavity than in the body of the house. It's the same power source, the only difference is temperature variation.




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  Reply # 871537 4-Aug-2013 11:48
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Most AV equipment is designed in isolation. Hence the impractical space requirements that are normally in owners manuals. I went through a similar process with my AV equipment a while ago, and one of the main things I discovered was there is a lot more to venting a cupboard than just forcing air into it. For a start, convection will not be your friend, in fact it will probably work against you as one component's heat output will affect the airflow around another.

Here are some things you may want to consider for your roof space cabinet;

Insulate the external surface to minimise summer heat transfer into the cabinet (and reduce condensation risk),

Extract the air rather than force it in,

Arrange components so most heat sensitive are closest to inlet(s),

Have a temperature indicator that you can see inside your house so you can keep track of conditions in the cabinet,

Use the waste heat for something useful, in my case the extracted air is ducted into our airing cupboard.

In the end, my situation is slightly different because I did away with the ceiling space idea and converted a cupboard. But many of the points are still relevant. What I did do with the ceiling space was built storage for all the crap that was in the cupboard that we wanted to keep but didn't need regular access to.



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  Reply # 871539 4-Aug-2013 11:55
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Extracting air from a cabinet in the ceiling would mean hot, dirty air from the ceiling cavity would get sucked into the case. The other way there's condensation. Overall perhaps it's not a great idea.

A regular cupboard up there for storage and putting electronics inside a cupboard sounds like a very sensible plan. The cupboard may still need some kind of ventilation, but not near as much work as putting things in the ceiling space. Genius! Sometimes the simplest plans are the best.




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  Reply # 871556 4-Aug-2013 13:15
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Yup. My cupboard just draws ambient air from inside the house. Cupboard door is an open louvre type so induction is simple. You may need to consider how you are letting air into the cupboard. The extraction to the airing cupboard has made a big difference on the laundry front, we installed a new cylinder a while back and its insulation was so effective we were getting no airing from it. The waste air from the AV cupboard restored the airing.




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  Reply # 871557 4-Aug-2013 13:15
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hmmm, sometimes I wonder if we make mountains out of molehills (and create a whole lot of work and expense unnecessarily). I have a DVR for security cameras and the control module for my burglar alarm in my roof space, sitting on an offcut of mdf. They have been there for the last 5 years, along with their standard power supplies with no issues. I pulled the DVR down about 12 months ago and opened it up to swap out the hard drive - there were no significant issues with dust (it has a small fan in it). Yes, it gets warm up there (we have a charcoal coloured concrete tile roof) but experience tells me the equipment is coping.

The rest of my stuff (2 routers, network printer, home server computer + standard power supplies) all reside together in a wardrobe. There is no ventilation, and it is noticeably warm when you open the door, but as above there have been no issues.

I guess I am saying that before you pull the chequebook out, do a little test run of the equipment with a maximum thermometer sitting alongside and see how big your problem actually is.



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  Reply # 871561 4-Aug-2013 13:31
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Thanks DB. Thanks for the reality check as well traderstu, may be unnecessary. I will say my ceiling area is super dusty and dirty in this old house, I was up there for half an hour this morning fixing up insulation, I got a lot of black stuff in my nose and ears.




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  Reply # 871564 4-Aug-2013 13:48
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It is common to alarm system equipment in the ceiling cavity. I've got the main control board, the remote control unit, the dialer, and the battery backup. When the alarm company installed it they never asked how hot it gets nor did they check for venting. So is the alarm equipment designed substantially differently or is it the different power profile that makes the difference?

I'm in the Wellington area and my steel roof used to raise the summer temperature in the roof cavity to over 60C. My head would start to sweat in a matter of seconds. There was so much heat that it was radiating from the ceiling and heating the house. It's now vented and doesn't go above 30-40C.

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  Reply # 871566 4-Aug-2013 13:52
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timmmay: Niel, can you explain why the power supplies will have more problems in the ceiling cavity than in the body of the house. It's the same power source, the only difference is temperature variation.


Temperature basically. The power supplies are frequently built to a [very cheap] price point, and don't always use the best quality components. Over time, electrolytic capacitors (which are common in power supply circuits) dry out, and cause all sorts of problems with the equipment connected to them. The process is rapidly accelerated by increased heat.

Have a look here for further info:

http://www.badcaps.net/

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