cooling a small server room

[serverroomcooling]

maybe when this is all said and done, this IT guy is gonna come up with the innovation that will change the HVAC world!!

72 is too warm for me to be comfortable

[serverroomcooling]

here's another question I have for you guys.....even if I put in a good tstat with the ability to keep the compressor and handler off for 5 minutes no matter what, in the hot, hot, hot spring/summer months, my server room is going to be way very, very hot, I would think that my racks will reach over 90 degrees, as they are 85 right now, and 5 minutes during that time of year will allow the inside temp to rise, which will cause the system to be on for longer, won't that cause the system to freeze over as well??

If I am right, I am thinking of purchasing one spot cooler to keep on during the hot summer months, and maybe even all the time (of course I have power considerationes here), but the spot cooler will allow the room to stay cooler, or at least just my equipment. Am I missing any points about the spot cooler? Will it have adverse affects on the hvac system?

[john dalton]

Dear Serverroomcooling,

Good morning from Los Angeles. I was going to say I hope you had a great Christmas, but I can see from your post, like some of us….you had to work. Oh well, such as life!

To answer your questions:

“…will this prevent another freeze, or will the handler running on an on cycle for too long also cause a freeze??”

In a word….No. The “delay on break” function of the thermostat is for the sole purpose of preventing the compressor from short cycling too much, thereby causing a premature failure of the compressor to start.

Am I stuck at setting the tstat at 72 or 73??

Not necessarily. With the data I requested we can investigate the possibility of adjusting the operating temperature lower. But we must have the data to do that, especially the CFM and air temperatures.

“….maybe when this is all said and done, this IT guy is gonna come up with the innovation that will change the HVAC world!! 72 is too warm for me to be comfortable…”

With all due respect……maybe when this is all over……..”this IT guy”…..will learn that an inexpensive HVAC system has its limitations. We in the industry have designed HVAC systems for rooms such as yours that have the capability to maintain any temperature you’d like….70, 60, 50, and so on….everything depends on your budget. You had a budget, which by definition budgets the HVAC system you installed. But don’t give up on the ship so soon.

Lets see if we can commission the system and get a better environment for you and your computers!

“…..even if I put in a good tstat with the ability to keep the compressor and handler off for 5 minutes…”

STOP……compressor in the condensing unit cycles, the air handler MUST remain on at all times!!!!!!!!!!!!

“…here's another question I have for you guys.....even if I put in a good tstat with the ability to keep the compressor and handler off for 5 minutes no matter what, in the hot, hot, hot spring/summer months, my server room is going to be way very, very hot, I would think that my racks will reach over 90 degrees, as they are 85 right now, and 5 minutes during that time of year will allow the inside temp to rise, which will cause the system to be on for longer, won't that cause the system to freeze over as well??”

In a word….NO! Your system is not freezing because it is running too long. Your system is freezing because it has not been commissioned to run properly…period! A properly designed and commissioned system has the ability to run 24 hours a day, 365/6 days a year.

“…If I am right, I am thinking of purchasing one spot cooler to keep on during the hot summer months, and maybe even all the time (of course I have power considerationes here), but the spot cooler will allow the room to stay cooler, or at least just my equipment. Am I missing any points about the spot cooler? Will it have adverse affects on the hvac system?”

Let’s stop for a moment. I’ll post more a few minutes.

Respectfully Submitted,
John J. Dalton

PS: A clarification, that’s a “delay on break” required thermostat…..must have been a long day…lol.

[serverroomcooling]

I don't think I will ever be happy with this system, I know it has limitations, I don't want it at all. I'll get my $20,000 system, but only after a major catastrophe, such is life in my industry. Loosing one hard drive from a RAID set isn't enough to scream bloody murder. Had I lost 5 from different systems I'd be able to say enough is enough.

That being said, I still have to make this thing work. I printed out this thread (which is over 50 printed pages) I think it will help me at least prove that I tried to make this thing work.

I will be bugging my HVAC guy to come in to gather those numbers....please post a brief sysnopsis of what I should ask of him (again) so that you can help me gather the info.

What really bothers me is that when all is said and done, the numbers are going to equal that of the $20,000 system that would be what I need. The system we have in now cost about $5,500 installed. The spot cooler rental is going to cost $4,800, and I'm going to end up buying one of them so that will probably be another $2,500, and I still have yet to find peace of mind....but at least I learned how to get the system back up and running after it freezes.

[serverroomcooling]

One other side question......when the temp goes down to the set temp, the handler shuts off, and so does the fan, should the fan always be running??

[john dalton]

Dear Serverroomcooling,

Just for informational sake, could you answer a few questions regarding your “one ton spot” cool systems:

These typical portably spot cool systems have two separate air intakes and two separate air outlets. Where were the air in and air out vents for the “cool air” and where were the condensing air in and out vents?

How much does one of these units cost you to buy and install in relationship to your new HVAC 3 ton system? Please no direct prices here! Just relationship….60%, 70%, ect. of the new system. What did you do with the condensate water, dumped by time, directly plumbed to a receptacle, ect?

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

When the system was running after you defrosted it, Saturday or Sunday during the day, did you happen to get the outside temperature and % of off and on cycles? This would tell us about potential heat loads.

Respectfully Submitted,
John J. Dalton

[serverroomcooling]

no, sorry, didn't get cycle information, but I remember it being about the same....I came in to fix everything sat night....I'd say it was 70 outside, maybe a bit less

spot cooler....I beilieve it sucks it from the room and out through the vent on the top....the vent is about a foot in diameter.

releation cost if it was new approx 3/4 of the hvac system currently installed, if I can get it used, which I might, and if my cost estimate is correct, the used one would be 1/3 of the cost of the new hvac system, the difference is that I know what I have with the spot coolers....given the choice, I might even opt to keep the spot coolers over the hvac system, but that is probably just my frustration speaking!!

If I will be keeping the spot coolers, I will install a float switch and water pump to pump the water from the spot cooler down the same drain that the hvac uses to get rid of its water

[john dalton]

Dear Serverroomcooling,

“..One other side question......when the temp goes down to the set temp, the handler shuts off, and so does the fan, should the fan always be running??”

The air handler should never shut off for several reasons such as:

When the air handler shuts off, even though there is still some air flow being generated with your equipment fans, there will be what’s known as stratification of air in the room. This is a separation of temperature layers in the room causing more exaggerated hot and cold spots in the room, and more separation of warmer air that rises to the ceiling and colder air that falls to the floor. The areas of your computer equipment that produces heat will have a tendency to remain hotter than normal even with their fans and the cooler areas of the room where no equipment is located will remain cooler, which will be of no benefit. All and I mean all computer and equipment rooms have their evaporative fans running all the times. Something your HVAC contractor should already know hopefully. Maybe that was just an oversight on his part.

Like I’ve said before…you MUST commission the system so it can work to its maximum potential.

Respectfully Submitted,
John J. Dalton

[serverroomcooling]

ok...I'm going to switch the fan from auto to on

[serverroomcooling]

my hvac guy just called....he told me to drop the temp to 70 and turn the fan to on instead of auto....he also said he wants to take the calculated numbers during a hot do, not on a day like today where the temp is 62 and was 55 this morning

[john dalton]

Dear Serverroomcooling,

Like I said before. Don’t give up on this ship quiet yet. I know….yes….I know, we can get the system working better than it is now. We just need information and we can help you commission this system to its maximum potential. Have two ands and a brain ready to work….lol.

The vent intake to the room and the vent outlet from the top of the spot cooler to the room was the return air from the room and the chilled air to cool the room I’m assuming. What about the condensing air in and out of the cooler, you should have had two hoses. One hose was air being sucked from somewhere other than the room and another hose to discharge the hot condensing air out of the room. Where were these two hoses?

Respectfully Submitted,
John J. Dalton

PS: We all get frustrated…but after we clear our heads, we’ll put them together and solve this problem!.

[john dalton]

Dear Serverroomcooling,

Would it be possible for you to get a little information for me this afternoon?

When the compressor cycles on and starts cooling, after it has ran for at least five minutes, could you get the return air grill temperature and then the supply air temperature(the air temperature coming from any one of the supply registers in the ceiling). This would give us a preliminary CFM/ton measurement which is extremely important in diagnosing and preventing freeze ups.

Respectfully Submitted,
John J. Dalton

PS: Understand the evaportive fan is now running all the time.

[serverroomcooling]

there are no hoses...this is truly a portable spot cooler, roll it in, pop a ceiling tile up, put in the vent cover, attach the duct, and the hot air gets blown into the ceiling. Air intake is from the room, It sucks in from one of the sides.

I think keeping the fan on at all times will help the situation a bit....I'm going into the room for 45 minutes to monitor the cycles

[john dalton]

Dear Serverroomcooling,

“..my hvac guy just called....he told me to drop the temp to 70 and turn the fan to on instead of auto....he also said he wants to take the calculated numbers during a hot do, not on a day like today where the temp is 62 and was 55 this morning…”

He probably is busy at this time, But……..

This system has several potential problems and one of them lies in the ability of this system to continue to cool in this cooler or even cold weather. These reading need to be taken when it’s hot outside, but they just as equally needs to be taken when its cool or even cold outside. Readings taken early in the morning when the temperature is 55 degrees F would be VERY important in ascertaining weather a condensing fan capacity control is needed to maintain system capacity and the PREVENT system freezing.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

“…I think keeping the fan on at all times will help the situation a bit....I'm going into the room for 45 minutes to monitor the cycles….”

Yes…this will help. Glad to see you’re monitoring……Can you get the outside temperature as well?

Did I see in one of your previous posts that you have the ability to measure what the humidity is inside the server room? If so, can you post that with the return and supply air readings to determine a preliminary CFM/ton number?

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

“…there are no hoses...this is truly a portable spot cooler, roll it in, pop a ceiling tile up, put in the vent cover, attach the duct, and the hot air gets blown into the ceiling. Air intake is from the room, It sucks in from one of the sides….”

That’s bad! The cool air from your server room is being sucked into the condensing part of the spot cooler and then being ducted to the space above the ceiling (that’s the correct ducting for the air out). But the suction on the spot cooler will create a highly negative pressure inside the server room and cause your new system to suck unconditioned, unfiltered, and at times un-cooled air from the surrounding areas. The proper use of these spot coolers in a server room such as yours is the following:

The spot cooler will have two hoses on it, the first will be the makeup air for the condensing unit and the second will be the hot air discharge from the condensing unit. BOTH hoses MUST be installed outside of the server room for proper operation. It will work without the second hose, but less efficiently, especially during times when the building HVAC central plant is not running (i.e. the times you need it the most).

More to follow.

Respectfully Submitted,
John J. Dalton

[serverroomcooling]

the guys just left, here's what they told me. They said that they need to come back on a hot day to take their caalibrations, b/c once they grab what they need and put in the proper amount of freon, they say we won't need to worry about the cold days b/c the freon will remain at a safe pressure. He didn't add anything today b/c the gas will expand and could blow the compressor when the temp gets hotter.

I asked about the short cycle tstat they didn't think I needed it once the system gets the proper amount of freon in it.

I guess if I decide to purchase a spot cooler it will be different than the one I have here now. I'll get the one you spoke about, it is probably just a different model.

but, maybe I won't need one, the guys set my tstat down to 65 and said the freeze had nothing to do with the temp it was set at. They did give me a reason, but I didn't quite follow. He had the gauges with him and still seems confident that the system will be ok....I'll continue to monitor, as this seems to be my new full time job :-)

I'll post my cylce times as soon as I have them with the tstat set to 65 and outside temp of 67 (now)

[john dalton]

Dear Serverroomcooling,

My comments as follows:

“…the guys just left, here's what they told me. They said that they need to come back on a hot day to take their caalibrations, b/c once they grab what they need and put in the proper amount of freon, they say we won't need to worry about the cold days b/c the freon will remain at a safe pressure. He didn't add anything today b/c the gas will expand and could blow the compressor when the temp gets hotter.”

It true that its much easier to charge a system when its hot outside, but……like I said its much earlier, not impossible. The proper thing would have been to properly charge the system now….and then on a hot day, recheck the charge if they are concerned about it. Next, “…when the system is properly charged…”…How long must we wait to properly charge the system, till the weather gets hot, how long will that be????.

And when the system is charged properly, you won’t have to worry about a cold….I just still don’t believe that for a moment!

He didn’t add today because it could blow the compressor…….yes it could, if he added way too much.

I asked about the short cycle tstat they didn't think I needed it once the system gets the proper amount of freon in it.

What???? Air conditioning isn’t rocket science, I think you should understand the following:

The cycle rate on the compressor will be a function of one thing and one thing OLNY!
It is a function of how fast your server room rises in temperature after the compressor cycles off. Notice I said “AFTER” the compressor cycles off. It DOS NOT depend on the HVAC system at all! So whether the HVAC system is charged properly or not, has nothing to do with the rise of temperature in your server room once the compressor is cycled off.

Some items that WILL affect the cycle rate will be how much computer equipment you have running, how hot it is outside, is the server room lights on, and whether the building air is on or off.

Worst case of short cycling will be under the following conditions:

You have the most computer equipment running.
You have the server room lights on.
The outside temperature is hot..
The building air has been off for some time.

The best case for short cycling will be under the following conditions:

You have the least of computer equipment running.
You have the server room lights off.
The outside temperature is cold.
The building air is on.

In short, as the heat load inside the server room increases, so will the cycle rate of the compressor, and inversely, as the heat load decreases inside the server room, so will the cycle rate of the compressor.

Do you see the system’s refrigerant charge, efficentency, or capacity anywhere in the above statement? You don’t because it has nothing whatsoever to do with the cycle rate; therefore your HVAC contractor is grossly incorrect in his statement.

“…I guess if I decide to purchase a spot cooler it will be different than the one I have here now. I'll get the one you spoke about, it is probably just a different model.”

All spot coolers are basically the same, its how they’re installed that’s the key. Your old spot coolers would probably be fine, if installed correctly. But let’s hold off on the spot cooler talk until the system is properly commissioned.

“…but, maybe I won't need one, the guys set my tstat down to 65 and said the freeze had nothing to do with the temp it was set at. They did give me a reason, but I didn't quite follow. He had the gauges with him and still seems confident that the system will be ok...”

Let’s see…..they came, they reset the thermostat to its original setting when it iced up before, they did nothing else, they offered an explanation that didn’t make sense to you, and they left. Gee, do you think the ice up problem has been resolved or do you think you’ll be back after hours and get some more experience defrosting the system after an ice up?

“…I'll continue to monitor, as this seems to be my new full time job :-) I'll post my cylce times as soon as I have them with the tstat set to 65 and outside temp of 67 (now)…”

I’ll be waiting. Could you please include the return and supply temperatures along with the inside humidity if possible?

And yes….we WILL solve this problem!

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

I’m leaving the office early this afternoon, but I’ll contact you when I get home…..waiting on those cycle rates and temperatures in and out of the HVAC system along with the indoor humidity if possible. I’ll stay in touch.

Respectfully Submitted,
John J. Dalton

PS: Keep smiling, you’re getting a great education in air conditioning along this rough road! Just think of how easier your next evaluation of proposed A/C will be. This is still salvageable. Honestly!

PSS: See you in about 45 – 60 minutes.