alt.certification.network-plus - BTU's from a Computer

Author

BTU's from a Computer

Jason Silva

2003-01-23, 9:24 am

Hey, the energy guy for a new building construction asked my boss to ask me
how many BTU's our computers are throwing out so he knows how big to make
the AC unit. WHAT! Maybe it's a valid question but I have never considered
heat from a PC as BTUs.

Can someone clarify this for me? Is this a valid question and if so, how do
I get at least an estimate of that?

Jason Silva

Crazymiclo30

2003-01-23, 9:24 am

British Thermal Units and you will just have to get a conversion chart I
guess.

"Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
> Hey, the energy guy for a new building construction asked my boss to ask
me
> how many BTU's our computers are throwing out so he knows how big to make
> the AC unit. WHAT! Maybe it's a valid question but I have never
considered
> heat from a PC as BTUs.
>
> Can someone clarify this for me? Is this a valid question and if so, how
do
> I get at least an estimate of that?
>
> Jason Silva
>
>

Al Dykes

2003-01-23, 10:24 am

In article <vNScnf7z2M9pn62jXTWcpQ@gwi.net>,
Jason Silva <jasons@yorkcountyfcu.com> wrote:
>Hey, the energy guy for a new building construction asked my boss to ask me
>how many BTU's our computers are throwing out so he knows how big to make
>the AC unit. WHAT! Maybe it's a valid question but I have never considered
>heat from a PC as BTUs.
>
>Can someone clarify this for me? Is this a valid question and if so, how do
>I get at least an estimate of that?
>
>Jason Silva
>
>

That heat's gotta go somewhere.

BTU/hr = watts * 3.4129
watts = volts * amps

Look at _all_ the equipment and figure the # of watts each item uses.
Big items have a nameplate somewhere with at least MAX amps and volts.

This is messy because (a) the the label on equipment is startup
current, which is generally greater that operating current, and (b)
watts = volts * amps really only applies to things like incandescent
light bulbs due to something called POWER FACTOR. If you ignore both
of these it will inflate your number and is therefore conservative.
It gets messier if it put you right over theh edge to the next larger
AC unit and hence big bucks.

Don't forget the BTUs for the lights and the people. Your HVAC guy
should have these numbers.

In general, commercial equipment like servers from the big names and
name brand PCs marketed to businesses have spec sheets that lists the
operating BTUs and you should be able to get these on the web. You might
find it in the manual.

--
Al Dykes
-----------
adykes@panix.com

Murli Zee

2003-01-23, 11:24 am

Biggest heat generators are the monitors. No need to account for the heat
dissipated by the desktop towers as this will only be a small fraction.
And the construction guys only need an estimate. Usually, they work by thumb
rules like if the floor is 3350sq. ft and the you want a staff of 50
working there, that comes out to almost X BTUs and Y sized Air conditioning.
Ask them if they've done this before, and what calculations they used.

"Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
> Hey, the energy guy for a new building construction asked my boss to ask
me
> how many BTU's our computers are throwing out so he knows how big to make
> the AC unit. WHAT! Maybe it's a valid question but I have never
considered
> heat from a PC as BTUs.
>
> Can someone clarify this for me? Is this a valid question and if so, how
do
> I get at least an estimate of that?
>
> Jason Silva
>
>

Barry Watzman

2003-01-23, 12:24 pm

I'd have to take issue with you on the monitor vs. computer heat
dissipation. The monitor draws 70 to 200 watts (typically), while a new
Pentium 4 computer will draw over 400 watts. The computer gives off
more heat.

[A 350 watt [output] power supply that is 66.66% efficient will draw
about 525 watts from the wall at full power output. Most computer power
supplies are probably 75% efficicent and run at less than full rated power].

Murli Zee wrote:
> Biggest heat generators are the monitors. No need to account for the heat
> dissipated by the desktop towers as this will only be a small fraction.
> And the construction guys only need an estimate. Usually, they work by thumb
> rules like if the floor is 3350sq. ft and the you want a staff of 50
> working there, that comes out to almost X BTUs and Y sized Air conditioning.
> Ask them if they've done this before, and what calculations they used.
>
>
> "Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
> news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
>
>>Hey, the energy guy for a new building construction asked my boss to ask
>
> me
>
>>how many BTU's our computers are throwing out so he knows how big to make
>>the AC unit. WHAT! Maybe it's a valid question but I have never
>
> considered
>
>>heat from a PC as BTUs.
>>
>>Can someone clarify this for me? Is this a valid question and if so, how
>
> do
>
>>I get at least an estimate of that?
>>
>>Jason Silva
>>
>>
>
>
>

Jason Silva

2003-01-23, 1:24 pm

Thanks, I did end finding the equation. And I also found out that a human
gives off about 600 BTUs. I felt like I was in the Matrix reading through
some of this stuff.

"Barry Watzman" <Watzman@neo.rr.com> wrote in message
news:3E3031E1.9040702@neo.rr.com...
> I'd have to take issue with you on the monitor vs. computer heat
> dissipation. The monitor draws 70 to 200 watts (typically), while a new
> Pentium 4 computer will draw over 400 watts. The computer gives off
> more heat.
>
> [A 350 watt [output] power supply that is 66.66% efficient will draw
> about 525 watts from the wall at full power output. Most computer power
> supplies are probably 75% efficicent and run at less than full rated
power].
>
>
> Murli Zee wrote:
> > Biggest heat generators are the monitors. No need to account for the
heat
> > dissipated by the desktop towers as this will only be a small fraction.
> > And the construction guys only need an estimate. Usually, they work by
thumb

> > rules like if the floor is 3350sq. ft and the you want a staff of 50
> > working there, that comes out to almost X BTUs and Y sized Air
conditioning.
> > Ask them if they've done this before, and what calculations they used.
> >
> >
> > "Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
> > news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
> >
> >>Hey, the energy guy for a new building construction asked my boss to ask
> >
> > me
> >
> >>how many BTU's our computers are throwing out so he knows how big to
make[
color=darkred]
> >>the AC unit. WHAT! Maybe it's a valid question but I have never
> >
> > considered
> >
> >>heat from a PC as BTUs.
> >>
> >>Can someone clarify this for me? Is this a valid question and if so,[/color]
how
> >
> > do
> >
> >>I get at least an estimate of that?
> >>
> >>Jason Silva
> >>
> >>
> >
> >
> >
>

Tom MacIntyre

2003-01-23, 5:24 pm

On Thu, 23 Jan 2003 09:57:56 -0500, "Jason Silva"
<jasons@yorkcountyfcu.com> wrote:

>Hey, the energy guy for a new building construction asked my boss to ask me
>how many BTU's our computers are throwing out so he knows how big to make
>the AC unit. WHAT! Maybe it's a valid question but I have never considered
>heat from a PC as BTUs.

BTU=British Thermal Unit...thermal means heat.

>
>Can someone clarify this for me? Is this a valid question and if so, how do
>I get at least an estimate of that?

There is a conversion factor between watts and BTU with time as a
factor; it's about .3 watt-hours per BTU. How to know what % of power
drawn is radiated as heat, and what fraction power drawn is of maximum
power supply power, is the trick, and I don't know how you'd do that.

I'd guess (WAG) that 30-35% of maximum rated power of all units would
cover it, perhaps even be overkill. There is likely a much better way,
probably using temperature increase in a controlled situation.

Tom

>
>Jason Silva
>

Tom MacIntyre

2003-01-23, 5:24 pm

On Thu, 23 Jan 2003 17:11:33 GMT, "Murli Zee"
<murliNO_SPAMzee@rogers.com> wrote:

>Biggest heat generators are the monitors. No need to account for the heat
>dissipated by the desktop towers as this will only be a small fraction.

I have monitored older systems (486's, for example, nowhere near as
power hungry and hot-running as today's systems), and large monitors
on an AC currewnt meter, and they draw simialar amounts of current, so
there's no chance that it's a small fraction, and indeed the BTU's
from a modern system may exceed that from a monitor. You don't see 2
and 3 fans on a monitor, do you? :-)

Tom

>And the construction guys only need an estimate. Usually, they work by thumb
>rules like if the floor is 3350sq. ft and the you want a staff of 50
>working there, that comes out to almost X BTUs and Y sized Air conditioning.
>Ask them if they've done this before, and what calculations they used.
>
>
>"Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
> news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
>> Hey, the energy guy for a new building construction asked my boss to ask
>me
>> how many BTU's our computers are throwing out so he knows how big to make
>> the AC unit. WHAT! Maybe it's a valid question but I have never
>considered
>> heat from a PC as BTUs.
>>
>> Can someone clarify this for me? Is this a valid question and if so, how
>do
>> I get at least an estimate of that?
>>
>> Jason Silva
>>
>>
>

Murli Zee

2003-01-23, 10:24 pm

Yup, you guyz are right!
Quick check on 2 new and 1 old pc reveals the wattage is almost same for the
system and the monitor. I'm trying to find the source where I got the wrong
information from.
Thanx!

"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:4fr03v40j3vg493qn70vt9adq
k5p8jg2v7@4ax.com...
> On Thu, 23 Jan 2003 17:11:33 GMT, "Murli Zee"
> <murliNO_SPAMzee@rogers.com> wrote:
>
> >Biggest heat generators are the monitors. No need to account for the heat
> >dissipated by the desktop towers as this will only be a small fraction.
>
> I have monitored older systems (486's, for example, nowhere near as
> power hungry and hot-running as today's systems), and large monitors
> on an AC currewnt meter, and they draw simialar amounts of current, so
> there's no chance that it's a small fraction, and indeed the BTU's
> from a modern system may exceed that from a monitor. You don't see 2
> and 3 fans on a monitor, do you? :-)
>
> Tom
>
> >And the construction guys only need an estimate. Usually, they work by
thumb

> >rules like if the floor is 3350sq. ft and the you want a staff of 50
> >working there, that comes out to almost X BTUs and Y sized Air
conditioning.
> >Ask them if they've done this before, and what calculations they used.
> >
> >
> >"Jason Silva" <jasons@yorkcountyfcu.com> wrote in message
> > news:vNScnf7z2M9pn62jXTWcpQ@gw
i.net...
> >> Hey, the energy guy for a new building construction asked my boss to
ask
> >me
> >> how many BTU's our computers are throwing out so he knows how big to
make[
color=darkred]
> >> the AC unit. WHAT! Maybe it's a valid question but I have never
> >considered
> >> heat from a PC as BTUs.
> >>
> >> Can someone clarify this for me? Is this a valid question and if so,[/color]
how
> >do
> >> I get at least an estimate of that?
> >>
> >> Jason Silva
> >>
> >>
> >
>

Charles M. Kozierok

2003-01-24, 8:24 am

In article <aw2Y9.438080$F2h1.84549@news01.bloor.is.net.cable.rogers.com>,
Murli Zee <murliNO_SPAMzee@rogers.com> wrote:
} Yup, you guyz are right!
} Quick check on 2 new and 1 old pc reveals the wattage is almost same for the
} system and the monitor. I'm trying to find the source where I got the wrong
} information from.
} Thanx!

Just remember that you really do need to check the actual current draw
on each device. You can't just look at the wattage on the faceplate. A
computer may have a 400W power supply, but that doesn't mean it really
draws 400W.

peace,

-*-
charles

Tom MacIntyre

2003-01-24, 7:24 pm

On Fri, 24 Jan 2003 13:40:53 +0000 (UTC), ixlu@PCGuide.com (Charles M.
Kozierok) wrote:

>In article <aw2Y9.438080$F2h1.84549@news01.bloor.is.net.cable.rogers.com>,
>Murli Zee <murliNO_SPAMzee@rogers.com> wrote:
>} Yup, you guyz are right!
>} Quick check on 2 new and 1 old pc reveals the wattage is almost same for the
>} system and the monitor. I'm trying to find the source where I got the wrong
>} information from.
>} Thanx!
>
>Just remember that you really do need to check the actual current draw
>on each device. You can't just look at the wattage on the faceplate. A
>computer may have a 400W power supply, but that doesn't mean it really
>draws 400W.
>
>peace,
>
>-*-
>charles

Right...as I stated, I tested 486 systems for current draw when I had
the chance, and typical draws were 60 watts or so when the PS was
rated at 200 or more. A typical 15-17" monitor was around the same
range. This was usually just with the PC idling, so I'd say the
monitor, on average, would be 45-55% of the total system draw; as
MultiZee said, almost the same. This still doesn't help with the
BTU's, as the efficiency of the system/monitor determines how much of
the input power is output as heat, and how much is not.

There are formulas for calculating BTU's based on temperature change
and room dimensions (I found one web site with such a calculator
yesterday), and that might be a more realistic way of getting this
done. There may be a different newsgroup with a more scientific slant
towards thermodynamics where an answer may be readily obtained. This
is practical application of physics in action.

Tom

Charles M. Kozierok

2003-01-25, 3:24 pm

In article < kho33vofvqeqvn49l2bt8bmev37t65
j8b4@4ax.com>,
Tom MacIntyre <tom__macintyre@hotmail.com> wrote:
} On Fri, 24 Jan 2003 13:40:53 +0000 (UTC), ixlu@PCGuide.com (Charles M.
} Kozierok) wrote:
}
} >In article <aw2Y9.438080$F2h1.84549@news01.bloor.is.net.cable.rogers.com>,
} >Murli Zee <murliNO_SPAMzee@rogers.com> wrote:
} >} Yup, you guyz are right!
} >} Quick check on 2 new and 1 old pc reveals the wattage is almost same for the
} >} system and the monitor. I'm trying to find the source where I got the wrong
} >} information from.
} >} Thanx!
} >
} >Just remember that you really do need to check the actual current draw
} >on each device. You can't just look at the wattage on the faceplate. A
} >computer may have a 400W power supply, but that doesn't mean it really
} >draws 400W.
} >
} >peace,
} >
} >-*-
} >charles
}
} Right...as I stated, I tested 486 systems for current draw when I had
} the chance, and typical draws were 60 watts or so when the PS was
} rated at 200 or more. A typical 15-17" monitor was around the same
} range. This was usually just with the PC idling, so I'd say the
} monitor, on average, would be 45-55% of the total system draw; as
} MultiZee said, almost the same. This still doesn't help with the
} BTU's, as the efficiency of the system/monitor determines how much of
} the input power is output as heat, and how much is not.

Yep, I was trying to reinforce what you said, Tom. Should have been more
specific.

peace,

-*-
charles

Tom MacIntyre

2003-01-25, 4:24 pm

On Sat, 25 Jan 2003 20:50:19 +0000 (UTC), ixlu@PCGuide.com (Charles M.
Kozierok) wrote:

>In article < kho33vofvqeqvn49l2bt8bmev37t65
j8b4@4ax.com>,
>Tom MacIntyre <tom__macintyre@hotmail.com> wrote:

>} Right...as I stated, I tested 486 systems for current draw when I had
>} the chance, and typical draws were 60 watts or so when the PS was
>} rated at 200 or more. A typical 15-17" monitor was around the same
>} range. This was usually just with the PC idling, so I'd say the
>} monitor, on average, would be 45-55% of the total system draw; as
>} MultiZee said, almost the same. This still doesn't help with the
>} BTU's, as the efficiency of the system/monitor determines how much of
>} the input power is output as heat, and how much is not.
>
>Yep, I was trying to reinforce what you said, Tom. Should have been more
>specific.

Heck...that's why I said "right"...I knew you were. I was just
elaborating on both my and your posts. :-)

Tom

>
>peace,
>
>-*-
>charles

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