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| Author |
Message |
| 25 new of 96 responses total. |
scg
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response 50 of 96:
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Aug 8 04:29 UTC 1995 |
re 40:
If I'm remembering correctly, cutting a hole through the South wall
into that other storage room would not be an option. I think there's a stone
wall behind the drywall.
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gregc
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response 51 of 96:
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Aug 8 05:47 UTC 1995 |
Yes, I looked at that yesterday, a rather ancient mortered stone wall.
It also looks to be load bearing. Also, that's the wall I want ot put shelving
against.
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rcurl
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response 52 of 96:
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Aug 8 08:01 UTC 1995 |
There is already an exhaust fan with 3" duct - which exhaust only 10%
of the heat. I think a muffin fan with 4-5 inch duct will still be
inadequate, unless you can show that it exhausts 400 cfm if from the
room, or 200 cfm if from just the Sun 3 heat vents.
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scott
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response 53 of 96:
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Aug 8 11:03 UTC 1995 |
If we dedicate that exhaust fan to only heated air from the Sun (which
produces the most hot air of any hardware), it could make a significant
difference. If we let the fan remove only room air, then the average temp.
of the air passing through the fan is much lower than if the fan is dedicated
to removing air used to cool the Sun. Even if the Sun exhaust just blew out
into the basement and was eventually sucked back into the Grex room, it would
be cooled off by its passage much more than if it just circulated around the
Grex room.
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n8nxf
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response 54 of 96:
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Aug 8 13:02 UTC 1995 |
47.1 The system I just tore apart was a Computervision Sun 3 chassis. The
power supply draws air in from the bottom for cooling. The boards are coold
from the top down by a larger fan as you say. (Why from the top down??!)
47.2 The ducting doesn't have to be complicated. Morph one of rectangular
air outlets into a 6" dia. opening and use flexable ducting to the outside.
You would, however, have to wack one lower side of the plastic enclosure
to properly attach the morphing adaptor to the blower unit.
47.3 If you do the adaptor right, it should not get in the way.
47.4 Disconnect the flex duct, as was suggested, when not needed.
47.5 I have a space problem in my house too. We have to get rid of stuff not
needed and make better use of the space we have. (Ya want the remains of
of a Computervision Sun 3? Brd. rack, 1KW supply, line / fuse / conditioner
box and even a fan but no boards. It's taking up space in my garage ;-)
Adaquate air circulation throught the Sun is a concern. After seening how
much dirt, dust, etc. had collected on the screens of the 32 M system I gutted
it seems there is significant over design in the cooling system. If the
screens in the enclosure are kept clean I think there should be enough air
circulation. (I should power up the fan I have and get a feel for it's
potential.)
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rcurl
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response 55 of 96:
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Aug 9 03:53 UTC 1995 |
The Sun produces just over 50% of the dungeon heat. It is also necessary
to exhaust room air, to prevent the other nearly 50% from overheating the
room. My suggested air flows are designed to do this. The air flow through
the Sun 3 itself is too small (note the 14 F rise across the Sun) to
prevent the room temperature from rising more than 5 F.
I'm looking at fans (for electronic equipment) in the Marlin P. Jones
catalog. Most of the "muffin" fans are rated ca. 10-20 cfm. The
maximum flow listed for any 5" fan is 130 cfm. These flow rates are
for open fans - no connected ductwork, which can reduce the flow rate
considerably. However three (3) 5" fans (@ $9 each) set directly in
the wall (no ducting) would exhaust 390 cfm, which would meet the
criterion, and not require a wall opening that presents a security
problem.
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gregc
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response 56 of 96:
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Aug 9 04:35 UTC 1995 |
Actually, Rane, I think the Sun itself produces at least, if not more than,
75% of the heat created in that room. Ducting all of the outflow air from tom
the Sun directly into the basement, bypassing the dungeon air, would
significantly reduce the room temperature.
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n8nxf
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response 57 of 96:
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Aug 9 11:25 UTC 1995 |
It should also be kept in mind that the Sun draws air from the dungeon.
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ajax
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response 58 of 96:
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Aug 9 14:01 UTC 1995 |
Dunno percentages, but modems are sometimes a lot hotter than you'd figure.
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rcurl
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response 59 of 96:
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Aug 9 18:22 UTC 1995 |
I would be glad for staff to refine the power figure. STeve measured it.
When he and I were there, we came up with a total of 1500 watts, with
850 (57%) from the Sun 3. Improved figures would improve the design.
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scott
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response 60 of 96:
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Aug 9 22:52 UTC 1995 |
It may be that we are just focussing on the Sun 3 because it would be the
easiest to capture heat from. However, if we could catch 50% of the heat with
a fairly simple kludge of hoses and fans it would still be a big improvement.
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popcorn
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response 61 of 96:
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Aug 9 22:59 UTC 1995 |
Re 58: Grex's modems are usually kinda hot, ja.
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rcurl
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response 62 of 96:
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Aug 10 06:01 UTC 1995 |
Re #60. No, it would not be a big improvement. Even if you put the
Sun 3 outside the dungeon, you leave ca. 650 watts inside. If that
were unventilated, the room would still get too hot (just not as hot).
Staff should put a desirable upper limit on the temperature for the
dungeon - for both the machines and for the comfort of those working
there. The day I was there the basement was at 80 F, and the dungeon
was 95 F with the door open. It was probably more like 105 before the
door had been opened. It was quite intolerable at 95 F. I have adopted
as my engineering criterion that the dungeon not exceed the basement
temperature by more than 5 F with the door closed (which would have
made it 85 F that day).
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n8nxf
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response 63 of 96:
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Aug 11 13:28 UTC 1995 |
I fired up a Compuvision cooling fan last night and feel that it does not
move the air at a hight enough velocity to make venting through ducting
practacle. The fan in itself is an energy hog, disipating 50 W! The
fan is also controlled by a little circuit containg a thermisor. This
may have been reducing the fans speed when the air temp is low.
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mju
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response 64 of 96:
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Aug 11 20:20 UTC 1995 |
On a suggestion from Greg, I removed the filter material from the
louvers in the door to the Dungeon. We may suck in a bit more dust this way,
but at least we'll get some air. The filter material was in there so densely
that Idoubt we were getting any airflow through the grille at all.
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gregc
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response 65 of 96:
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Aug 12 00:01 UTC 1995 |
Re #63:
Yes, that is the whole point. The CV's fan is temperature controlled. When
the air temp is low, the fan barely spins, when things get hot however, that
fan moves a significant amount of air. The point is, that it does what it
was designed for, it cools the interior of the box. There is less than a
10 degree delta between inflow and outflow air temperature from the box.
The problem is not air temp in the box per se, it is air temp in the *room*.
The quality/speed/volume of the fan in the box is not going to change the
temperature of the room, and thereby, the temperature of the inflow air.
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mdw
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response 66 of 96:
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Aug 12 07:57 UTC 1995 |
The simplest solution would be to put a *large* louvered opening in the
door. It's the same solution people have adopted for ages for getting
air in/out of mechanical or electrical storage closets, and a wide
variety of cheap yet secure solutions exist. It would be even better
yet if it could be put in a wall instead, of course, and if it's put in
a wall, it's quite feasible to put a really heavy duty iron grill on the
thing. Neither of these will significantly compromise security, and the
iron bar approach may even insigificantly increase security.
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n8nxf
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response 67 of 96:
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Aug 13 20:57 UTC 1995 |
Most of the computer rooms I've seen are climate controled environments. Temp.
and humidity are maintained to tight tolerances and the air in the room is well
filtered. Keep an eye out for used AC units once winter hits. The prices and
selection of used equipment will be better.
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gregc
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response 68 of 96:
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Aug 13 22:18 UTC 1995 |
The SUns are actually fairly tolerant of high heat.While we could probably
pick up a used A/C unit for under $200, I'm more concerned with the $30 to
$50 a month in electricity it could cost to run it, and the fact that we have
no window to mount it in means we'd have to invest a fair amount of manpower
coming up with some kind of ducting system. Add to this I would worry about
putting an A/C unit on our Power line. Visualize this: The A/C compressor
kicks on, and the Sun dims, so to speak. :-)
I think our best bet is just to come up with a better ventilation system
to get more air into the room and exchanged out into the basement.
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rcurl
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response 69 of 96:
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Aug 14 06:24 UTC 1995 |
The proposal to have larger louvred openings is insufficient. The
desired air exchange rate is 400 hundred - count them, 400 - cubic
feet per minute (cfm), to keep the room temperature rise to 5 F.
This is attainable with fans that do not draw much power. No ducting
is needed to exhaust to the basement (which is where all the heat
goes now). The remaining question to address is any need to filter
dust out of the circulating air.
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mdw
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response 70 of 96:
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Aug 14 10:03 UTC 1995 |
It would be good to get the dust out, yes.
The smaller the opening, the noisier the fan, and the longer and more
tortuous the path to wherever is, and the more backpressure & less
airflow there is. Small muffins fans are probably rated for air
delivery in new condition, under no back pressure situations; not for
operation after one year of operation in a high dust high humidity
situation, through a filter that will no doubt trap quite a bit of
"stuff", into a non-optimally routed duct and the non-trivial
possibility of being accidently blocked by yard equipment.
Sometimes, in engineering, it's worth overengineering. In this case,
this isn't rocket technology - you need only look at your typical
building air conditioning & heating systems to see time tested solutions
for moving air around. They almost never go for tiny muffin fans and
small ductwork.
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n8nxf
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response 71 of 96:
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Aug 14 12:41 UTC 1995 |
A regular furnace filter would do an OK job of filtering the air. It could
be attached to the back side of a vent. I suspect a 10 or 12" fan from
K-Mart, gutted from its stand and installed in an opening in the wall, would
move the required 400 cfm. I have a pretty wide selection of blowers / fans
that Grex would be welcome to. I even have a blower removed from my old
forced air furnace ;-)
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davel
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response 72 of 96:
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Aug 14 12:58 UTC 1995 |
That opening in the wall is likely to be a *major* sticking point in the
current environment.
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rcurl
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response 73 of 96:
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Aug 15 06:17 UTC 1995 |
Why? Nobody will want to climb in through a 10-12 inch hole with a fan
whirring in it. Besides, there are lots of places where the wall of
the dungeon is close to but not touching a basement wall, absolutely
preventing egress.
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gregc
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response 74 of 96:
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Aug 15 09:56 UTC 1995 |
I think they were reffering more to the work required to do this, and
getting permissions to cut holes in the dungeon walls.
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