I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

On Sep 29, 7:52*pm, markm75 wrote:
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

Thats why they make windows that open

If it's that cold outside, consider building an air exchanger, to blow cold
outdoor air into the computer room.

Or, run the fan on the furnace all the time. The electric heat (computers)
is expensive heat in many parts of the world. Would be a shame to discard
that heat. Then your furnace could cycle less often.

A good HVAC guy could put a freeze stat on a window unit.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"markm75" wrote in message
...
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

markm75 wrote:
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

I sympathize.

I once worked for a company that had a small (mainframe) computer room. Had
two five-ton AC units on the roof.

One of the AC units had a thermal disconnect to disable the unit when the
outside ambient temperature reached (I believe) 40°F.

One night the temperature got below freezing and the computer was running.
About 3:00 a.m., the thermal interlocks on all the computer equipment
popped. This required a service call from IBM to reset and test all the
equipment ($).

After much WTFs over several hours, a simple snip with wire cutters solved
the problem.*

In your case, an inquiry to the AC manufacturer of the unit you're
contemplating seems to be indicated.

----------
* The operator was queried thusly: "When it started getting hot, why didn't
you shut the son-of-a-bitch down?"
His reply: "I had to get the work done!"

The unanswerable rejoinder: "Then why didn't you open the freakin' door!"

markm75 wrote:
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

I do a lot of commercial HVAC and refrigeration
work and when I have to run a piece of equipment
under low ambient conditions like the AC at a
restaurant which often has to run in the winter,
I install whats called a "head pressure" or "low
ambient" control. For the large AC unit that you
would find at a restaurant, it's a simple matter
of controlling the condenser fan. When the fan
is turned off by the electric controller, the head
pressure rises until reaching a preset limit then
the condenser fan comes back on. This keeps things
from freezing up and protects the compressor from
flooding with liquid freon. The problem with a
window unit is that there is only one motor turning
both condenser and evaporator fans. To control the
head pressure in that situation you need to modify
the plumbing and add a head pressure control that
controls the flow of freon. This type of control
throttles the head pressure by opening and closing
a valve to keep the head pressure within a certain
range. What I've written here is a bit simplistic
in explaining the process but a good refrigeration
guy could modify your window unit. Most AC techs
don't get into plumbed in controls which is what
refrigeration techs tackle all the time. Here are
some links to information that may help you grasp
the process and explain in more detail than I can
here.

http://tinyurl.com/52houb

http://tinyurl.com/4f8xr3

I hope this helps you out.

[8~{} Uncle Monster

On Mon, 29 Sep 2008 21:29:32 -0700 (PDT), ransley
wrote:



Thats why they make windows that open

More superior advice from the resident dumbass. You obvioulsly don't
have a clue when it comes to heating and air.

"Uncle Monster" wrote in message
...
markm75 wrote:
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

I do a lot of commercial HVAC and refrigeration
work and when I have to run a piece of equipment
under low ambient conditions like the AC at a
restaurant which often has to run in the winter,
I install whats called a "head pressure" or "low
ambient" control. For the large AC unit that you
would find at a restaurant, it's a simple matter
of controlling the condenser fan. When the fan
is turned off by the electric controller, the head
pressure rises until reaching a preset limit then
the condenser fan comes back on. This keeps things
from freezing up and protects the compressor from
flooding with liquid freon.

Sorry Uncle that does not stop refrigerant from floading compressor
but actually does the oposit however it helps for compressor from
cutting out on low pressure switch and saving compressor from
pumping oil out of crankcase. However for the health of compressor
if unit is going to be use all year round additional items need to be
install
(depend) on system size, Crankcase heater, suction accumulator,
large Recivers also need rap around heater.


The problem with a
window unit is that there is only one motor turning
both condenser and evaporator fans. To control the
head pressure in that situation you need to modify
the plumbing and add a head pressure control that
controls the flow of freon. This type of control
throttles the head pressure by opening and closing
a valve to keep the head pressure within a certain
range. What I've written here is a bit simplistic
in explaining the process but a good refrigeration
guy could modify your window unit. Most AC techs
don't get into plumbed in controls which is what
refrigeration techs tackle all the time. Here are
some links to information that may help you grasp
the process and explain in more detail than I can
here.

http://tinyurl.com/52houb

http://tinyurl.com/4f8xr3

I hope this helps you out.

[8~{} Uncle Monster

Old and Grunpy wrote:
"Uncle Monster" wrote in message
...
markm75 wrote:
I'm lookin to get an AC window unit in my 9x12 office.. not sure on
the btu i would need, but i have a lot of computer equipment forcing
the ambient temp in the room from about 78 to as high as 85 at times
(at mid height in the room)..

I've had window units years ago and i remember having trouble when it
got colder.. the unit would freeze up.. do they all do this these
days.. as i'd need to run this unit in the winter time too..

I'm hoping to find one with thermostat control, so when the room
reaches a temp it shuts off too.

We have whole house ac, but this room gets hot, despite this.

Thanks for any advice..

I do a lot of commercial HVAC and refrigeration
work and when I have to run a piece of equipment
under low ambient conditions like the AC at a
restaurant which often has to run in the winter,
I install whats called a "head pressure" or "low
ambient" control. For the large AC unit that you
would find at a restaurant, it's a simple matter
of controlling the condenser fan. When the fan
is turned off by the electric controller, the head
pressure rises until reaching a preset limit then
the condenser fan comes back on. This keeps things
from freezing up and protects the compressor from
flooding with liquid freon.

Sorry Uncle that does not stop refrigerant from floading compressor
but actually does the oposit however it helps for compressor from
cutting out on low pressure switch and saving compressor from
pumping oil out of crankcase. However for the health of compressor
if unit is going to be use all year round additional items need to be
install
(depend) on system size, Crankcase heater, suction accumulator,
large Recivers also need rap around heater.


The problem with a
window unit is that there is only one motor turning
both condenser and evaporator fans. To control the
head pressure in that situation you need to modify
the plumbing and add a head pressure control that
controls the flow of freon. This type of control
throttles the head pressure by opening and closing
a valve to keep the head pressure within a certain
range. What I've written here is a bit simplistic
in explaining the process but a good refrigeration
guy could modify your window unit. Most AC techs
don't get into plumbed in controls which is what
refrigeration techs tackle all the time. Here are
some links to information that may help you grasp
the process and explain in more detail than I can
here.

http://tinyurl.com/52houb

http://tinyurl.com/4f8xr3

I hope this helps you out.

[8~{} Uncle Monster



Most of the systems I install have crankcase
heaters anyway. When I order a new unit I get
all the bells and whistles like high and low
pressure cutouts, phase/voltage protection
modules, head pressure controls, etc. Some of
the units have suction line accumulators like
the 4 ton Carrier condensing unit here at the
office. Somebody got on the roof last summer
and thought it belonged to my neighbor in the
next shop, the silly ******* left the service
valves loose and all the freon got loose and
went off to kill some helpless little ozones.
It took 13lbs of R22 to recharge it and until
I saw this huge accumulator next to the
compressor, I wondered where in the hell the
charge was going. In my previous post I said
my explanation was "simplistic". Anyway, I
posted what I thought would work for the guy
in another thread and suggested a portable AC
unit which is what I've used to cool small
computer server rooms before. The whole unit
is in the room and uses a big hose to exhaust
hot air. No low ambient problems there.

http://www.portableairshop.com/

[8~{} Uncle Monster

With the usual wiring, the compressor and fan come on at the same time. This
also happens in window units; compressor and condensor fan are wired on the
same switch. However, in too cold outdoor weather, this results in too cold
refrigerant feeding into the evaporator. Could easily be sub freezing temp
refrigerant, which would cause evaporator icing. Can also result in poor
liquid to vapor conversion in the evaporator. Leading to liquid return to
the compressor. The restaurant units I've serviced used a pressure control
to turn on the condensor fan. A thermal control could be used, but I've not
seen one.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Old and Grunpy" t. wrote in message
...


I do a lot of commercial HVAC and refrigeration
work and when I have to run a piece of equipment
under low ambient conditions like the AC at a
restaurant which often has to run in the winter,
I install whats called a "head pressure" or "low
ambient" control. For the large AC unit that you
would find at a restaurant, it's a simple matter
of controlling the condenser fan. When the fan
is turned off by the electric controller, the head
pressure rises until reaching a preset limit then
the condenser fan comes back on. This keeps things
from freezing up and protects the compressor from
flooding with liquid freon.

Sorry Uncle that does not stop refrigerant from floading compressor
but actually does the oposit however it helps for compressor from
cutting out on low pressure switch and saving compressor from
pumping oil out of crankcase. However for the health of compressor
if unit is going to be use all year round additional items need to be
install
(depend) on system size, Crankcase heater, suction accumulator,
large Recivers also need rap around heater.

Dear Tony, got to disagree with you.

The headmaster control (switches on and off condensor fan) does stop
refrigerant from floading (try spelling it "flooding") the compressor.
Since the headmaster control keeps the refrigerant to the evaporator fairly
warm, the refrigerant can then turn to vapor. This provides for good
cooling, and reduces the odds of evaporator freezing.

Yes, headmaster switch does help compressor from cutting out on low pressure
switch. Has very little to do with pumping oil out of crankcase.

Crankcase heater is good in the winter. suction accumulator, can reduce
risk of oil slugging the compressor. I don't think that "large Recivers also
need rap around heater", the receiver is typically in the air flow from the
condensor. As such, it stays plenty warm. Which music group would you get to
rap around the heater? Glad it's outdoors, most restaurants don't like rap
music. Unless they are in the city. I've had a couple cases where the hot
blast of air from the condensor was over heating the receiver, and I've
wrapped it in cardboard so the refrigerant would not pick up more heat.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Old and Grunpy" t. wrote in message
...

I do a lot of commercial HVAC and refrigeration
work and when I have to run a piece of equipment
under low ambient conditions like the AC at a
restaurant which often has to run in the winter,
I install whats called a "head pressure" or "low
ambient" control. For the large AC unit that you
would find at a restaurant, it's a simple matter
of controlling the condenser fan. When the fan
is turned off by the electric controller, the head
pressure rises until reaching a preset limit then
the condenser fan comes back on. This keeps things
from freezing up and protects the compressor from
flooding with liquid freon.

Sorry Uncle that does not stop refrigerant from floading compressor
but actually does the oposit however it helps for compressor from
cutting out on low pressure switch and saving compressor from
pumping oil out of crankcase. However for the health of compressor
if unit is going to be use all year round additional items need to be
install
(depend) on system size, Crankcase heater, suction accumulator,
large Recivers also need rap around heater.

Stormin Mormon wrote:
With the usual wiring, the compressor and fan come on at the same time. This
also happens in window units; compressor and condensor fan are wired on the
same switch. However, in too cold outdoor weather, this results in too cold
refrigerant feeding into the evaporator. Could easily be sub freezing temp
refrigerant, which would cause evaporator icing. Can also result in poor
liquid to vapor conversion in the evaporator. Leading to liquid return to
the compressor. The restaurant units I've serviced used a pressure control
to turn on the condensor fan. A thermal control could be used, but I've not
seen one.

ICM makes temperature sensing electronic head pressure controls
that I use all the time.

http://www.grainger.com/Grainger/items/4MG75

http://www.part-s-mart.com/store/par...bient-kit.html

http://www.thefind.com/appliances/in...essure-control

[8~{} Uncle Monster