cooling a small server room

[twcpipes]

Next questions:

Your budget is extremely short if you "never want to be down".

I don't know if your budget is for a complete installation but there is also electrical service to be done as I am sure you have found out as well as the outdoor equipment location set up. In other words roof work for platform and sealing or at ground level for outdoor type unit(s).

What have the three contractors proposed for equipment referring to split system or package or?
Also, to "never be down" you might want to consider redundancy with two systems or at least an exhaust to pull the heat out when, or if, the a/c fails. I am surmising you have surrounding areas of conditioned space.
Thanx, tom

[serverroomcooling]

I have backup plans to cool the room in the case of a failure, I will be notified via pager if the temp rises above the set threshold.

My budget is not set by my department. I would love to spend 20,000 as that would give me the leverage to put in redundant systems that will help me avoid executing my disaster plans....but I need to work withing my means for now.

[twcpipes]

two splits given you are going that way wouldn't be worth $20,000 especially if both were installed at the same time.
anyway, good luck to you
tom

[serverroomcooling]

If anyone is in the South Florida area and would like to come by and quote me a reliable system, please let me know

[serverroomcooling]

I have decided on buying a 3.5 Ton 12.25 seer Trane unit with an A frame handler on the server room floor. I will be placing 3 ducts in the ceiling in front of my server racks, and one in the back corner (which actually comes to a point, the room is like a rectangle, but as you walk to the back, the room ends up in a triangle). The duct will be back there providing cool air for my switches, and the handler should pull that air back around the other side of the servers where the heat is and possible cool that area too. The handler will be on a stand and will suck air from the bottom for maximum airflow (or at least that's what I've been told when stressing that I need max airflow)

If 3.5 tons is too much, I will move a duct either just into the ceiling or use it to cool another room.

I'll let you guys know how it goes....thanks for all the help, and let me know what you think of this configuration

[thehumid1]

Sounds pretty much the way the gut selling Goodman quoted except it is a Trane.

[serverroomcooling]

it is the guy who quoted the Goodman, I told him to get me a more known unit.

below is a scetch of the room. The Vs are vents in the ceiling, and the Rs are Racks, only the top 3 are there. It's approx 100 Square feet

/\
/ \
/ V \
| \
| V |
| R |
| V R |
| R |
| V R |
| |
|H_____|

[serverroomcooling]

============/\=============================================
===========/==\============================================
==========/====\===========================================
=========/======\==========================================
========/========\=========================================
=======/====V=====\======================================= =
======|============\============================== =========
======|=============\============================= =========
======|=V==R====*====|============================ =========
======|==============|============================ =========
======|=V==R====*====|============================ =========
======|==============|============================ =========
======|==V==R====*===|============================ =========
======|==============|============================ =========
======|====R=========|============================ =========
======|==============|============================ =========
======_H____door_______=========================== ========

maybe this picture is better
V is ceiling vent
R is server rack
* is heat spots behind the racks
H is the handler

[flange]

well, after visiting a new customer today, i can tell you what doesnt work. installing a three ton heatpump in the northeast, not having enough control wires for a heatpump, not having low ambient kit installed, and not pulling any return from the server room DEFINATELY doesnt work! this is what i found today. just wanted to drop this note, because the installing contractor for that one charged right around the high end of your budget. Needless to say, with the drastic temp changes around here, plus the need for humidity control, the customer wasted his first eight grand, now he will be spending more than double that to make things right. as they say, look first before you leap.

[twcpipes]

If you have another minute:

Please post what exactly your contractor is proposing in writing without the price, please.
Thanx, tom

[an "expert"]

I would definitely recommend an engineer get involved, you can re-route the blame if it doesn't work.
If that is not an expense the customer is willing to take ( they always hate to spend money ) 1 watt = 3.412 BTU's, so take it from there.

[an "expert"]

I've been involved with the exact (health care) application that you described. The ductless splits worked, but the room was always running on the edge.
Hot air rises, which stops the cold air from falling.
Supply the air under the floor and up is the only way to go.

[serverroomcooling]

under the floor is not an option....I will have to see what happens with this config....I have a high velocity fan if things don't work right. I can use that to move the air around.....3 tons of air coming down in front of the servers getting sucked in from the front, heated up and expelled out the back....hopefully the back will be the only hot areas...I would assume that the area near the handler might be warm too, but server rooms are like that, even when they are built properly....If things go really bad I guess I could build ducts to bring the air to the floor and blow it up from there

[serverroomcooling]

here is the proposal I will be using. a 3 ton Trane commercail grade unit. 12.25 seer. I have asked him again and again if the unit will survive day after day, week after week, month after month, year after year, of the system never turning off, as the second the system shuts off, the room will heat up in less than a few minutes if not faster, so this unit will basically be running 24/7 through the hot summer months. He assures me again and again that it will be fine, and that he has installed these systems in transmitter rooms with other types of electronics that heat up a room the smae way my server racks do, and they are working fine. He also does a lot of work in my building (which is comprised of 2, 7 floor towers) and wants to continue to do work for the building as well as the other buildings that are under my building management's auspices. So I believe he does not want the unit to fail as the building is very involved in this project.

I'm keeping my fingers crossed

[twcpipes]

1. Insure he is adding "head pressure control" for the system to operate at maximum tonnage in the cooler/colder weather. Also a Thermal Expansion Valve should be used and not a fixed orifice. Your contractor will know what that is.
2. What floor are you on, and where is the outdoor unit to be installed? Line sizes for the refrigerant lines?
3. Has he included the condensate drain, and to where does it terminate and how?
4. What type of thermostat is to be furnished and installed, and where will be its location.
5. Has an alarm been figured into the plan for over-temp?
They make some real neat modems with pre-recorded messages that will call a phone of your choice and leave a message you put on it. Such as "Hey guy, your room is getting hot so it is not working day in and day out, bye!"

Thank you,
tom

[thehumid1]

Originally posted by twcpipes
1. Insure he is adding "head pressure control" for the system to operate at maximum tonnage in the cooler/colder weather. Also a Thermal Expansion Valve should be used and not a fixed orifice. Your contractor will know what that is.
2. What floor are you on, and where is the outdoor unit to be installed? Line sizes for the refrigerant lines?
3. Has he included the condensate drain, and to where does it terminate and how?
4. What type of thermostat is to be furnished and installed, and where will be its location.
5. Has an alarm been figured into the plan for over-temp?
They make some real neat modems with pre-recorded messages that will call a phone of your choice and leave a message you put on it. Such as "Hey guy, your room is getting hot so it is not working day in and day out, bye!"

Thank you,
tom

1) A head pressure or weatherization control in Hollywood Florida is absolutely unnecessary but a TXV will give your system better efficiency.

The rest of the advice is sound especially like #5 which has been mentioned a few times in this thread.

The way your contractor has designed your system with the airhandler standing inside the room it should pick up most of the heat by the floor coming out of the servers so the cold air will drop. I see 4 supply drops with a 3-ton they will have to be about 12" each. If there is a drop ceiling he will probably use a lay in diffuser anyway so you won't have your hair being blown back as you walk by it and from what you have discussed so far I would say you have made an informed decision and picked a pretty competent installer which is worth a 1000 times more than any brand name
poorly installed.

[serverroomcooling]

there wil be some kind of pump sending the water to the drain, and the compressor will be on the roof...we are on the top floor. As for the TXV, I will ask for one and see what he says....the line size....I'm not sure, but I'm confident that he will install the appropriate size.

we will put in a digital thermostat....as to where it will be installed, I'm leaving that up to him and will take any suggestions from the crowd. I'm not sure what to do about it, if I place it on the wall in front of the servers and set it at 65, and then see that the rom is good that way, I would think that is fine....maybe I could put it on the back wall behind the servers and set it at 75, I'm not sure what would be best.

I have a system that will monitor the room temp and notify my staff if it reaches unacceptable temps. I haven't set it up since I haven't yet had a stable enviornment.

The floors are lynolium tiles, hope I got that spelling right. The ceiling tiles are sealed with caulk and the door is weather proofed as well to keep the room preasurized for the Inergen Fire Supression System we have protecting the equipment from fire.

[twcpipes]

Question about the below statement in your last post:

as the national Weather Service shows Jan-Mar ambients of 59-63 degrees and then again in Dec of 62. Depending on the ratio of NRE of the cooling coil to space tonnage requirements, are we sure there will always be an at, or near, 100psig drop across the TXV to accomplish required tonnage when needed? Especially if a higher efficient condenser is used.

*1) A head pressure or weatherization control in Hollywood Florida is absolutely unnecessary but a TXV will give your system better efficiency.*

[acddc]

one other detail

data centers/computer rooms are designed at 500cfm/ton not the traditional 400cfm/ton for filtering purposes.this will drop your air side delta-T. that will be normal when you have your bottom dollar service co. checking things dont let them get misled down a path of a problem that does not exist. (typically overcharge the system).

Allen

[thehumid1]

Originally posted by twcpipes
Question about the below statement in your last post:

as the national Weather Service shows Jan-Mar ambients of 59-63 degrees and then again in Dec of 62. Depending on the ratio of NRE of the cooling coil to space tonnage requirements, are we sure there will always be an at, or near, 100psig drop across the TXV to accomplish required tonnage when needed? Especially if a higher efficient condenser is used.

*1) A head pressure or weatherization control in Hollywood Florida is absolutely unnecessary but a TXV will give your system better efficiency.*

Well first of all I never trust weathermen but those ambients seem extremely low for that area of South Florida what city where you looking at and the only times I used them there was on walk-in cooler/ refrigeration applications and most of them don't even have one. Sure there will be conditions like maybe 3-10 days out the year where it could actually be used. And I can never always be sure of anything in this business like a 100 psig drop across the txv......as there are many variables that can affect this one of which is low ambient temp causing too much subcooling of the LL.
So you if you are designing a system to meet every posible extreme necessary regardless if the condition is only going to exist 1% of the time than I would agree it is necessary. In this case I would call it overkill.