Crackheads need for crackpot solutions to frosty problem.

[George Macdonald]

On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:
A friend of mine put his washer and dryer in the basementinstead of in the ground-floor laundry room of the househe moved into last winter. The laundry room was thenturned into his office.

Hmmm, I hope he has a washer which "supports" the stand-pipe height - many
are limited to ~6 feet vertical "climb".
Over the summer I used the existing dryer exhaust ventto duct the hot exhaust air from his Opteron dualie directlyto the great outdoors. That changed the office from beinguncomfortably warm on hot days to being just another room.We decided to try something different for the winter:use the duct to draw cold air in from outside, cool thecomputer, and then exhaust the warmed up air to the room.That usually works great: on most days even under loadthe cpu fans automatically turn themselves to their slowestspeed and the case fan and PSU fan can be manually turnedto their lowest speeds and everything run nice and cool.The silence is deafening.However, today it hit -33'C and now the air coming out theback of the PSU is -5'C, which cools the room off prettydarned fast. We tried ducting the cold exhaust air backoutside - which solved the room temperature problem nicely.

If that's basically your case temp it's far too low for many of the
components in the system, which can have a min operating temp of ~5C - hell
some have a min specified storage temp of -5->-10C. On top of that the
extremes of temp between Summer and Winter and On/Off are going to cause
temp ramps which can cause damage, not to mention operating temp gradients
on individual components and excessive fretting of contacts. Check the HDD
first for min operating temp.
(The turning point seems to be about -18'C: cold air intothe computer, room temperature air out.)However, when we do that a new problem crops up: frost buildsup on the outside of the case and also on things inside thecase that don't produce enough heat. We can't for the lifeof us figure out why ducting the cold exhaust back outsideis causing this. When I stand on a ladder outside the house,airflow from the exhaust duct is good and is noticably muchwarmer than the ambient outside temperature.

Do you have a vent hood/flap on the exhaust vent, as one has with a dryer
exhaust? I don't see how you can seal the case well enough to prevent the
leakage in of some ambient room air.
One more datum: If we disconnect the five foot flexibleinsulated exhaust duct from the hole in the wall and letthe exhaust blow through the ducting and into the room,the frost problem goes away. Hook that duct back up tothe hole in the wall and the frost comes back.Also: both the intake duct and the exhaust duct are about4 feet above the floor in the room and horizontally about2 feet apart. Outside, that places them about 10 feet abovethe ground and 5 feet below the soffits. It is a breezy day,but that side of the house is out of the wind.

I'd suggest you just disconnect the external air duct in Winter and use the
computer as a background heater... unless maybe it's an overclocking
project.:-)

Rgds, George Macdonald

[Rob Stow]

George Macdonald wrote: On Tue, 04 Jan 2005 19:47:03 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:A friend of mine put his washer and dryer in the basementinstead of in the ground-floor laundry room of the househe moved into last winter. The laundry room was thenturned into his office. Hmmm, I hope he has a washer which "supports" the stand-pipe height - many are limited to ~6 feet vertical "climb".

The stand-pipe is only about three feet tall.
Over the summer I used the existing dryer exhaust ventto duct the hot exhaust air from his Opteron dualie directlyto the great outdoors. That changed the office from beinguncomfortably warm on hot days to being just another room.We decided to try something different for the winter:use the duct to draw cold air in from outside, cool thecomputer, and then exhaust the warmed up air to the room.That usually works great: on most days even under loadthe cpu fans automatically turn themselves to their slowestspeed and the case fan and PSU fan can be manually turnedto their lowest speeds and everything run nice and cool.The silence is deafening.However, today it hit -33'C and now the air coming out theback of the PSU is -5'C, which cools the room off prettydarned fast. We tried ducting the cold exhaust air backoutside - which solved the room temperature problem nicely. If that's basically your case temp it's far too low for many of the components in the system, which can have a min operating temp of ~5C - hell some have a min specified storage temp of -5->-10C. On top of that the extremes of temp between Summer and Winter and On/Off are going to cause temp ramps which can cause damage, not to mention operating temp gradients on individual components and excessive fretting of contacts. Check the HDD first for min operating temp.

The hard drives do quite well. The cold air intake is
never opened up until after the system has been powered
up, so the drives never really have a chance to cool off.

Nevertheless, I will consider doing something like setting
up a lowest-priority task to continuously copy a small file
back and forth between the drives to make sure they never
go idle.

The DVD drive, however, has been a concern.
(The turning point seems to be about -18'C: cold air intothe computer, room temperature air out.)However, when we do that a new problem crops up: frost buildsup on the outside of the case and also on things inside thecase that don't produce enough heat. We can't for the lifeof us figure out why ducting the cold exhaust back outsideis causing this. When I stand on a ladder outside the house,airflow from the exhaust duct is good and is noticably muchwarmer than the ambient outside temperature. Do you have a vent hood/flap on the exhaust vent, as one has with a dryer exhaust? I don't see how you can seal the case well enough to prevent the leakage in of some ambient room air.

There is a hood but no flap. Just a quarter inch
mesh to keep out birds ;-) There is a lever on
each vent close them when the computer is not in
use.
One more datum: If we disconnect the five foot flexibleinsulated exhaust duct from the hole in the wall and letthe exhaust blow through the ducting and into the room,the frost problem goes away. Hook that duct back up tothe hole in the wall and the frost comes back.Also: both the intake duct and the exhaust duct are about4 feet above the floor in the room and horizontally about2 feet apart. Outside, that places them about 10 feet abovethe ground and 5 feet below the soffits. It is a breezy day,but that side of the house is out of the wind. I'd suggest you just disconnect the external air duct in Winter and use the computer as a background heater... unless maybe it's an overclocking project.:-)

Its a silencing project. The motherboard (Tyan S2885) doesn't
provide much in the way of overclocking capabilities ;-)

Cooling the system with cold air allows both CPU fans, the
PSU fan, and the single case fan to all run at their slowest
speeds. And - so far - the Radeon 9800 Pro has been quite
happy with passive cooling.

When cooling with air from inside the house, not only do all
of the fans need to spin faster - and much louder - but a
second case fan is also needed.

[Rob Stow]

We have kludged up something that so far seems to work,
but a real test will have to wait until temperatures
fall again - it is only -21'C tonight.

We have connected the case fan to a thermostat, with
the exhaust air from the PSU blowing over the thermostat.
The PSU exhaust is no longer vented back outside. The
120 mm case fan has also been replaced with an 80 mm fan
with no increase in RPMs.

As many air gaps as possible were sealed with tape on the
/inside/ of the case. Around front drive bay covers, for
example. The side panels now feature weatherstripping. :-)
This should dramatically reduce the amount of warm, moist
indoor air that leaks into the case.

The case fan now only kicks in when the PSU exhaust
convinces the thermostat that the temperature has risen
to 15'C. In case it was not clear, the case fan is used
to draw the cold air in from outside and blow it into
the case. When the case fan is not running, the PSU fan
does all of the work.

At -21'C outdoor temp, the case fan spins about 80% of
the time.

[Edmund]

On Thu, 06 Jan 2005 07:32:50 GMT, Rob Stow <rob.stow.nospam@shaw.ca>
wrote:
We have kludged up something that so far seems to work,but a real test will have to wait until temperaturesfall again - it is only -21'C tonight.We have connected the case fan to a thermostat, withthe exhaust air from the PSU blowing over the thermostat.The PSU exhaust is no longer vented back outside. The120 mm case fan has also been replaced with an 80 mm fanwith no increase in RPMs.As many air gaps as possible were sealed with tape on the/inside/ of the case. Around front drive bay covers, forexample. The side panels now feature weatherstripping. :-)This should dramatically reduce the amount of warm, moistindoor air that leaks into the case.The case fan now only kicks in when the PSU exhaustconvinces the thermostat that the temperature has risento 15'C. In case it was not clear, the case fan is usedto draw the cold air in from outside and blow it intothe case. When the case fan is not running, the PSU fandoes all of the work.At -21'C outdoor temp, the case fan spins about 80% ofthe time.

I like the idea, which I had a hole in my PC room wall! ;p

I'd probably add some desiccant packs (big ones) to the bottom and top
of the inside of the case to help keep moisture at a minimum, not sure
how much they'd really last or help though with constant moving air.

What sort of system do you have, you doing some massive over clocking or
just going for max cool and quite?

Cheers,
Ed
--
O'Hare Airport-Light Snow-25F

[Robert Redelmeier]

Rob Stow <rob.stow.nospam@shaw.ca> wrote: The PSU exhaust is no longer vented back outside. The 120 mm case fan has also been replaced with an 80 mm fan with no increase in RPMs.

This is a _huge_ change. That case fan capacity has been
reduced by ~56%. From always positive, the case pressure
may now go negative so you'll need ...
As many air gaps as possible were sealed with tape on the /inside/ of the case. Around front drive bay covers,

It's still very hard to seal tight.
The case fan now only kicks in when the PSU exhaust convinces the thermostat that the temperature has risen to 15'C. In case it was not clear, the case fan is used to draw the cold air in from outside and blow it into the case. When the case fan is not running, the PSU fan does all of the work.

And at these times, the case is at minimum pressure.
At -21'C outdoor temp, the case fan spins about 80% of the time.

Interesting. That's one hot box, or airflow is somehow
restricted. IIRC, an 80 mm fan moves about 7cfm (depending
on speed & restrictions). 7cfm @ 15'C is about 4.3 g/s.
Warming air 36C' requires 36 J/g. So that box was putting
out 155W. That's quite a bit for a machine at idle.

-- Robert

[Rob Stow]

Robert Redelmeier wrote: Rob Stow <rob.stow.nospam@shaw.ca> wrote:The PSU exhaust is no longer vented back outside.The 120 mm case fan has also been replaced with an80 mm fan with no increase in RPMs. This is a _huge_ change. That case fan capacity has been reduced by ~56%. From always positive, the case pressure may now go negative so you'll need ...

The 120 mm fan went back in.

It got all the way up to -12'C and when the air is that warm
the 80 mm fan just can't push enough air into the case unless
we run it at its medium speed. At that speed it is noticeably
noisier than the slower 120 mm fan while still moving less air
We figure it is about 7 cfm for 80 mm at medium speed vs
10 cfm for 120 mm at slow speed. And the whole point of this
scheme is noise reduction.
As many air gaps as possible were sealed with tape onthe /inside/ of the case. Around front drive bay covers, It's still very hard to seal tight.

Even so, we got it tight enough that even with the 80 mm
fan we had positive pressure in the case. But, of course,
negative pressure when the fan wasn't spinning.

The case fan now only kicks in when the PSU exhaust convincesthe thermostat that the temperature has risen to 15'C.In case it was not clear, the case fan is used to draw thecold air in from outside and blow it into the case. When thecase fan is not running, the PSU fan does all of the work. And at these times, the case is at minimum pressure.

Yup.

Tonight we are going to try something different.
Two stacked 80 mm fans case fans with one going all
the time at its lowest speed and one hooked up to the
thermostat. Hopefully that will allow us to maintain
positive pressure all the time with a fan in reserve for
when higher air flow is needed. Similarly doubling up
the PSU exhaust fan is also an option.

I have read about a cpu cooler that uses two stacked
fans spinning in opposite directions for higher airflow
and reduced noise, so we are reasonably confident that
the stacked fan idea will work.
At -21'C outdoor temp, the case fan spins about 80% ofthe time. Interesting. That's one hot box, or airflow is somehow restricted. IIRC, an 80 mm fan moves about 7cfm (depending on speed & restrictions). 7cfm @ 15'C is about 4.3 g/s. Warming air 36C' requires 36 J/g. So that box was putting out 155W. That's quite a bit for a machine at idle.

Its got a pair of Opty 248's, six 200 GB SATA drives,
a Radeon 9800 Pro, eight 1 GB PC3200 DIMMs, and sundry
others, plus heat wasted by PSU inefficiency. Not hard
to hit 155 W even when idle.

Measuring at the wall outlet shows a quick climb to 390 W
when the system boots up, then it settles down to about
360 W under normal usage (it is primarily used for semi-pro
video editting). When idle the draw is about 210 W.

[Rob Stow]

Ed wrote: On Thu, 06 Jan 2005 07:32:50 GMT, Rob Stow <rob.stow.nospam@shaw.ca> wrote:We have kludged up something that so far seems to work,but a real test will have to wait until temperaturesfall again - it is only -21'C tonight.We have connected the case fan to a thermostat, withthe exhaust air from the PSU blowing over the thermostat.The PSU exhaust is no longer vented back outside. The120 mm case fan has also been replaced with an 80 mm fanwith no increase in RPMs.As many air gaps as possible were sealed with tape on the/inside/ of the case. Around front drive bay covers, forexample. The side panels now feature weatherstripping. :-)This should dramatically reduce the amount of warm, moistindoor air that leaks into the case.The case fan now only kicks in when the PSU exhaustconvinces the thermostat that the temperature has risento 15'C. In case it was not clear, the case fan is usedto draw the cold air in from outside and blow it intothe case. When the case fan is not running, the PSU fandoes all of the work.At -21'C outdoor temp, the case fan spins about 80% ofthe time. I like the idea, which I had a hole in my PC room wall! ;p

It is easier than you think to make a hole like that.
Just be careful to not hit any power lines and to seal
it *very* well so you don't have moist air leaking into
the wall where it will condense on the insulation.

However, consider something else I'd like to try some day:
Use a water cooling kit but put the radiator outside. That
way you would only need two 10 mm holes for the coolant
hoses plus another small hole to provide power to fans
on the radiator during the warm weather. (Alternatively,
just move the radiator into the house for the summer.)
I'd probably add some desiccant packs (big ones) to the bottom and top of the inside of the case to help keep moisture at a minimum, not sure how much they'd really last or help though with constant moving air. What sort of system do you have,

Its not mine. It belongs to a friend who does semi-pro
video editting. I just get to play around with it and
do weird experiments like this one.

I built the system for him, so I know ever little thing
inside it. It is based on the Tyan S2885, with two Opty
248's, 8 GB of PC3200, six 200 GB SATA drives, a DVD burner,
and a Radeon 9800 Pro.

He recently upgraded from Opty 240's so now I've got
his old processors as the first step towards building
my own Opty dualie.
you doing some massive over clocking or just going for max cool and quite?

Just cool and quiet. The motherboard has no real
overclocking options.

[Robert Redelmeier]

Rob Stow <rob.stow.nospam@shaw.ca> wrote: it is noticeably noisier than the slower 120 mm fan while still moving less air We figure it is about 7 cfm for 80 mm at medium speed vs 10 cfm for 120 mm at slow speed. And the whole point of this scheme is noise reduction.

OK.
Tonight we are going to try something different. Two stacked 80 mm fans case fans with one going all the time at its lowest speed and one hooked up to the thermostat. Hopefully

Sounds good. Preferably run the downstream fan constantly,
the upstream on t'stat.

I guess a measured hole on the cold inlet would be a little bit
noisier because the fans will run a bit more. I wouldn't worry
about humidity unless the room has a hot air duct blowing in.
The PSU exhaust should keep the room positive.
that will allow us to maintain positive pressure all the time

Good.
I have read about a cpu cooler that uses two stacked fans spinning in opposite directions for higher airflow and

Stacked fans work (mor head, same flow). Reverse requires
blades cut just so.
Its got a pair of Opty 248's, six 200 GB SATA drives, a Radeon 9800 Pro, eight 1 GB PC3200 DIMMs, and sundry others, plus heat wasted by PSU inefficiency. Not hard to hit 155 W even when idle.
Measuring at the wall outlet shows a quick climb to 390 W when the system boots up, then it settles down to about 360 W under normal usage (it is primarily used for semi-pro video editting). When idle the draw is about 210 W.

Wow! That's a pretty loaded box. My guess is that vidcard
is a pretty big draw.

-- Robert

[Rob Stow]

Robert Redelmeier wrote: Rob Stow <rob.stow.nospam@shaw.ca> wrote:it is noticeably noisier than the slower 120 mm fan whilestill moving less air We figure it is about 7 cfm for 80mm at medium speed vs 10 cfm for 120 mm at slow speed.And the whole point of this scheme is noise reduction. OK.Tonight we are going to try something different. Two stacked80 mm fans case fans with one going all the time at itslowest speed and one hooked up to the thermostat. Hopefully Sounds good. Preferably run the downstream fan constantly, the upstream on t'stat. I guess a measured hole on the cold inlet would be a little bit noisier because the fans will run a bit more. I wouldn't worry about humidity unless the room has a hot air duct blowing in.

It doesn't. It was originally intended to be just a laundry
room so no provision was made for heating or air conditioning.

That computer (and a dual Xeon box in the same room) made
the room is extremely warm in the summer, hence the initial
attempt to make use of the dryer vent holes for summertime
heat exhaust. Winter use of those vent holes for computer
cooling is just a fun experiment.

[Mike Tomlinson]

In article <WPeDd.733063$%k.670821@pd7tw2no>, Rob Stow
<rob.stow.nospam@shaw.ca> writes
Measuring at the wall outlet shows a quick climb to 390 Wwhen the system boots up, then it settles down to about360 W under normal usage (it is primarily used for semi-provideo editting). When idle the draw is about 210 W.

Taking 210W and multiplying by the typical PSU efficiency of 0.7 gives
147W, which is in the ballpark of the 155W calculated.

--
..sigmonster on vacation

[Rob Stow]

Mike Tomlinson wrote: In article <WPeDd.733063$%k.670821@pd7tw2no>, Rob Stow <rob.stow.nospam@shaw.ca> writesMeasuring at the wall outlet shows a quick climb to 390 Wwhen the system boots up, then it settles down to about360 W under normal usage (it is primarily used for semi-provideo editting). When idle the draw is about 210 W. Taking 210W and multiplying by the typical PSU efficiency of 0.7 gives 147W, which is in the ballpark of the 155W calculated.

Except the 30% PSU /ineffiency/ is turned into heat by
the PSU, which in turn helps to heat up the cold air - and
it was the amount of energy needed to heat up that air that
led Mr. Redelmeier to come up with the 155 W number.