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Posted by on July 7, 2006, 5:03 pm
Hi I'm just a layman and a newbie at HVAC. I am looking for second or
third opinions on the advice that we're getting from a local HVAC
engineer.
We have a computer room that needs more cooling capacity. Currently
there are 2 cooling units, about 5 tons each. This has been adequate,
until one of them fails. Also we are adding a lot of computer and
network equipment and expect to add a lot more. We expect to need 25 -
30 tons at the end of 5 years from now.
The computer room has a raised floor with only cabling underneath and
no room for anything else. There is a drop ceiling, which contains the
supply and return ducts. The air cooling is done in a room in the
floor above. Apparently there is no more room above the drop ceiling
for more ducting. The approach we've been using so far is the cold
aisle/hot aisle method, where you dump cold air in the aisle between
two rows of computer racks, suck the cold air through the computer
equipment and dump the warm air in the aisles behind the racks, where
the return ducting sucks up the warm air. Seems to work fine.
We've hired a local HVAC consulting engineer but I'm not sure he's had
much computer room experience. We don't want to put additional cooling
units inside the computer room itself. His advice was to add a
mechanical room to our building right next to the computer room (ground
level), put the cooling units in the mechanical room, and punch holes
through the computer room's outside concrete wall for the ducting.
There would be 2 Lieberts of 25 tons each. The supply ducting would be
two semi-circular rings that run just under the drop ceiling and right
against the walls. There would be no return ducting, just two big
return vents built right into the outside wall back to the cooling
units.
So it looks to me like he's just going to let the new cooling units
cool the room air as a whole, instead of dumping the cold air in the
cold aisles. He seems to know what he's doing but I don't know if this
approach is OK. I guess he's depending on the air to just mix around
but is that good enough? I know he's really overloaded with work so
I'm just a little nervous that he may not be putting enough thought
into this, but I don't know enough to question his approach.
Any thoughts or advice?
Thanks.
Armin
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Posted by Fat Eddy on July 7, 2006, 6:32 pm
aboschmann@hydro.mb.ca wrote:
> Hi I'm just a layman and a newbie at HVAC. I am looking for second or
> third opinions on the advice that we're getting from a local HVAC
> engineer.
> We have a computer room that needs more cooling capacity. Currently
> there are 2 cooling units, about 5 tons each. This has been adequate,
> until one of them fails. Also we are adding a lot of computer and
> network equipment and expect to add a lot more. We expect to need 25 -
> 30 tons at the end of 5 years from now.
> The computer room has a raised floor with only cabling underneath and
> no room for anything else. There is a drop ceiling, which contains the
> supply and return ducts. The air cooling is done in a room in the
> floor above. Apparently there is no more room above the drop ceiling
> for more ducting. The approach we've been using so far is the cold
> aisle/hot aisle method, where you dump cold air in the aisle between
> two rows of computer racks, suck the cold air through the computer
> equipment and dump the warm air in the aisles behind the racks, where
> the return ducting sucks up the warm air. Seems to work fine.
> We've hired a local HVAC consulting engineer but I'm not sure he's had
> much computer room experience. We don't want to put additional cooling
> units inside the computer room itself. His advice was to add a
> mechanical room to our building right next to the computer room (ground
> level), put the cooling units in the mechanical room, and punch holes
> through the computer room's outside concrete wall for the ducting.
> There would be 2 Lieberts of 25 tons each. The supply ducting would be
> two semi-circular rings that run just under the drop ceiling and right
> against the walls. There would be no return ducting, just two big
> return vents built right into the outside wall back to the cooling
> units.
> So it looks to me like he's just going to let the new cooling units
> cool the room air as a whole, instead of dumping the cold air in the
> cold aisles. He seems to know what he's doing but I don't know if this
> approach is OK. I guess he's depending on the air to just mix around
> but is that good enough? I know he's really overloaded with work so
> I'm just a little nervous that he may not be putting enough thought
> into this, but I don't know enough to question his approach.
> Any thoughts or advice?
> Thanks.
> Armin
Well Armin, it sounds as though he is not given much opportunity due to
the limited space constraints that he has to work with, if I were
suspect of the design I would ask him to show me another setup like the
one that you describe, I can tell you from my experience that there are
a lot data centers out there that have air patterns similar to what he
is describing.
Fat Eddy
www.hvactalkforum.com
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Posted by on July 7, 2006, 9:21 pm
Fat Eddy wrote:
> aboschmann@hydro.mb.ca wrote:
> > Hi I'm just a layman and a newbie at HVAC. I am looking for second or
> > third opinions on the advice that we're getting from a local HVAC
> > engineer.
> > We have a computer room that needs more cooling capacity. Currently
> > there are 2 cooling units, about 5 tons each. This has been adequate,
> > until one of them fails. Also we are adding a lot of computer and
> > network equipment and expect to add a lot more. We expect to need 25 -
> > 30 tons at the end of 5 years from now.
> > The computer room has a raised floor with only cabling underneath and
> > no room for anything else. There is a drop ceiling, which contains the
> > supply and return ducts. The air cooling is done in a room in the
> > floor above. Apparently there is no more room above the drop ceiling
> > for more ducting. The approach we've been using so far is the cold
> > aisle/hot aisle method, where you dump cold air in the aisle between
> > two rows of computer racks, suck the cold air through the computer
> > equipment and dump the warm air in the aisles behind the racks, where
> > the return ducting sucks up the warm air. Seems to work fine.
> > We've hired a local HVAC consulting engineer but I'm not sure he's had
> > much computer room experience. We don't want to put additional cooling
> > units inside the computer room itself. His advice was to add a
> > mechanical room to our building right next to the computer room (ground
> > level), put the cooling units in the mechanical room, and punch holes
> > through the computer room's outside concrete wall for the ducting.
> > There would be 2 Lieberts of 25 tons each. The supply ducting would be
> > two semi-circular rings that run just under the drop ceiling and right
> > against the walls. There would be no return ducting, just two big
> > return vents built right into the outside wall back to the cooling
> > units.
> > So it looks to me like he's just going to let the new cooling units
> > cool the room air as a whole, instead of dumping the cold air in the
> > cold aisles. He seems to know what he's doing but I don't know if this
> > approach is OK. I guess he's depending on the air to just mix around
> > but is that good enough? I know he's really overloaded with work so
> > I'm just a little nervous that he may not be putting enough thought
> > into this, but I don't know enough to question his approach.
> > Any thoughts or advice?
> > Thanks.
> > Armin
> Well Armin, it sounds as though he is not given much opportunity due to
> the limited space constraints that he has to work with, if I were
> suspect of the design I would ask him to show me another setup like the
> one that you describe, I can tell you from my experience that there are
> a lot data centers out there that have air patterns similar to what he
> is describing.
> Fat Eddy
> www.hvactalkforum.com
Thanks! OK, that's useful information "there are a lot of data centers
out there that have air patterns similar...". I still don't know why
he wouldn't run the supply ducting right over the cold aisles. Maybe
he's thinking it's to our advantage to keep the ducting to the sides,
for when racks are moved or power distribution unit expansions are
installed. I think there's enough room but maybe I need to have a
closer look.
Thanks again! It's a load off just to know it's "within normal".
Armin
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Posted by PrecisionMachinisT on July 7, 2006, 8:24 pm
> Hi I'm just a layman and a newbie at HVAC. I am looking for second or
> third opinions on the advice that we're getting from a local HVAC
> engineer.
> We have a computer room that needs more cooling capacity. Currently
> there are 2 cooling units, about 5 tons each. This has been adequate,
> until one of them fails. Also we are adding a lot of computer and
> network equipment and expect to add a lot more. We expect to need 25 -
> 30 tons at the end of 5 years from now.
> The computer room has a raised floor with only cabling underneath and
> no room for anything else. There is a drop ceiling, which contains the
> supply and return ducts. The air cooling is done in a room in the
> floor above. Apparently there is no more room above the drop ceiling
> for more ducting. The approach we've been using so far is the cold
> aisle/hot aisle method, where you dump cold air in the aisle between
> two rows of computer racks, suck the cold air through the computer
> equipment and dump the warm air in the aisles behind the racks, where
> the return ducting sucks up the warm air. Seems to work fine.
> We've hired a local HVAC consulting engineer but I'm not sure he's had
> much computer room experience. We don't want to put additional cooling
> units inside the computer room itself. His advice was to add a
> mechanical room to our building right next to the computer room (ground
> level), put the cooling units in the mechanical room, and punch holes
> through the computer room's outside concrete wall for the ducting.
> There would be 2 Lieberts of 25 tons each. The supply ducting would be
> two semi-circular rings that run just under the drop ceiling and right
> against the walls. There would be no return ducting, just two big
> return vents built right into the outside wall back to the cooling
> units.
> So it looks to me like he's just going to let the new cooling units
> cool the room air as a whole, instead of dumping the cold air in the
> cold aisles. He seems to know what he's doing but I don't know if this
> approach is OK. I guess he's depending on the air to just mix around
> but is that good enough? I know he's really overloaded with work so
> I'm just a little nervous that he may not be putting enough thought
> into this, but I don't know enough to question his approach.
> Any thoughts or advice?
Suggest maybe look into installing water source units in the floor above the
computer room ( ducting as before ) and installing a chiller either at
ground level or up on the rooftop.
Concievably, water source heat pumps could subsequently be added onto the
chiller loop in order to recover any excess heat ( for wintertime usage in
other parts of the structure) if / when it's needed.
--
SVL
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Posted by on July 7, 2006, 9:29 pm
PrecisionMachinisT wrote:
> > Hi I'm just a layman and a newbie at HVAC. I am looking for second or
> > third opinions on the advice that we're getting from a local HVAC
> > engineer.
> > We have a computer room that needs more cooling capacity. Currently
> > there are 2 cooling units, about 5 tons each. This has been adequate,
> > until one of them fails. Also we are adding a lot of computer and
> > network equipment and expect to add a lot more. We expect to need 25 -
> > 30 tons at the end of 5 years from now.
> > The computer room has a raised floor with only cabling underneath and
> > no room for anything else. There is a drop ceiling, which contains the
> > supply and return ducts. The air cooling is done in a room in the
> > floor above. Apparently there is no more room above the drop ceiling
> > for more ducting. The approach we've been using so far is the cold
> > aisle/hot aisle method, where you dump cold air in the aisle between
> > two rows of computer racks, suck the cold air through the computer
> > equipment and dump the warm air in the aisles behind the racks, where
> > the return ducting sucks up the warm air. Seems to work fine.
> > We've hired a local HVAC consulting engineer but I'm not sure he's had
> > much computer room experience. We don't want to put additional cooling
> > units inside the computer room itself. His advice was to add a
> > mechanical room to our building right next to the computer room (ground
> > level), put the cooling units in the mechanical room, and punch holes
> > through the computer room's outside concrete wall for the ducting.
> > There would be 2 Lieberts of 25 tons each. The supply ducting would be
> > two semi-circular rings that run just under the drop ceiling and right
> > against the walls. There would be no return ducting, just two big
> > return vents built right into the outside wall back to the cooling
> > units.
> > So it looks to me like he's just going to let the new cooling units
> > cool the room air as a whole, instead of dumping the cold air in the
> > cold aisles. He seems to know what he's doing but I don't know if this
> > approach is OK. I guess he's depending on the air to just mix around
> > but is that good enough? I know he's really overloaded with work so
> > I'm just a little nervous that he may not be putting enough thought
> > into this, but I don't know enough to question his approach.
> > Any thoughts or advice?
> Suggest maybe look into installing water source units in the floor above the
> computer room ( ducting as before ) and installing a chiller either at
> ground level or up on the rooftop.
> Concievably, water source heat pumps could subsequently be added onto the
> chiller loop in order to recover any excess heat ( for wintertime usage in
> other parts of the structure) if / when it's needed.
> --
> SVL
Thanks SVL/PrecisionMachinisT for the thoughts. I think he discarded
the water source idea. I will discuss.
Armin
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> third opinions on the advice that we're getting from a local HVAC
> engineer.
> We have a computer room that needs more cooling capacity. Currently
> there are 2 cooling units, about 5 tons each. This has been adequate,
> until one of them fails. Also we are adding a lot of computer and
> network equipment and expect to add a lot more. We expect to need 25 -
> 30 tons at the end of 5 years from now.
> The computer room has a raised floor with only cabling underneath and
> no room for anything else. There is a drop ceiling, which contains the
> supply and return ducts. The air cooling is done in a room in the
> floor above. Apparently there is no more room above the drop ceiling
> for more ducting. The approach we've been using so far is the cold
> aisle/hot aisle method, where you dump cold air in the aisle between
> two rows of computer racks, suck the cold air through the computer
> equipment and dump the warm air in the aisles behind the racks, where
> the return ducting sucks up the warm air. Seems to work fine.
> We've hired a local HVAC consulting engineer but I'm not sure he's had
> much computer room experience. We don't want to put additional cooling
> units inside the computer room itself. His advice was to add a
> mechanical room to our building right next to the computer room (ground
> level), put the cooling units in the mechanical room, and punch holes
> through the computer room's outside concrete wall for the ducting.
> There would be 2 Lieberts of 25 tons each. The supply ducting would be
> two semi-circular rings that run just under the drop ceiling and right
> against the walls. There would be no return ducting, just two big
> return vents built right into the outside wall back to the cooling
> units.
> So it looks to me like he's just going to let the new cooling units
> cool the room air as a whole, instead of dumping the cold air in the
> cold aisles. He seems to know what he's doing but I don't know if this
> approach is OK. I guess he's depending on the air to just mix around
> but is that good enough? I know he's really overloaded with work so
> I'm just a little nervous that he may not be putting enough thought
> into this, but I don't know enough to question his approach.
> Any thoughts or advice?
> Thanks.
> Armin