12-24-2004, 12:41 PM
I don't work for the government, I am in long term healthcare....we had a 1.5 ton unit put in which died on the first weekend of use. I wanted to put in a system specifically designed to handle server rooms, but the price tag was too high and was denied. HVAC contractors came in and told me that it can be done for much cheaper, and I was skeptical. I did tons of research before starting this thread, and appreciate all the work you guys have done to help me. I actually am part of an IT community which works like this site. I help as many people as I can when I have the time......
After moving my Acurite thermometer to the air handler and placing its temp probe directly under the filer for the handler's return, I decided to watch and document the cycles, this time with the flourecent lights on
I walked in, at 11:19 and the unit was already on...
11:19 acurite temp reading 65.5 ath the return grill
11:27 cycle off 64.2
11:32:15 cycle on 69.6
11:50 64.0 cycle off
11:55 goes up to 70.9 and cycles on
I also have 2 springfield thermometers and humidity readers which read 75 behind the servers (no direct contact with vent air), and 72 in front of the servers (also with no direct contact)
this seems to be 18 minutes on, with 5 minutes off, and the air temp at the return grill ranges from 64.2 to 70.9 from cycle off to cycle on
Merry Christmas everyone....and I am not expecting responses. I am going home soon, but will be back on Sunday for more testing and monitoring
12-26-2004, 06:21 PM
ok, here is an update.....the first real test was saturday, after the building AC had been off since 7 PM friday night, the system did not survive the day without freezing over. At about 9:00 the temp in the room began to rise as the system began to shut down. I was able to get to the office in time to shut the systems down, thaw out the handler and reset the tstat to 72, and all day sunday it was fine. So 72 is a good safe temp, at least this time of year. I believe that magic number was mentioned above. 72 is a bit high for me since the equipment now reads at about 83-84 during main building AC off times, and I would like that to be lower.
We mentioned that a more expensive tstat would allow me to make sure that the system does not turn on again until after 5 minutes has passed....will this prevent another freeze, or will the handler running on an on cycle for too long also cause a freeze??
Am I stuck at setting the tstat at 72 or 73??
12-26-2004, 08:12 PM
>>>>the system did not survive the day without freezing over<<<
Isn't that amazing how the refrigerant cycle just never seems to change. 80 years and it is still the same.
12-27-2004, 08:48 AM
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
12-27-2004, 10:18 AM
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?
12-27-2004, 11:12 AM
Don't give up the ship quiet yet....
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.
John J. Dalton
PS: A clarification, that’s a “delay on break” required thermostat…..must have been a long day…lol.
12-27-2004, 11:28 AM
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.
12-27-2004, 11:29 AM
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??
12-27-2004, 11:38 AM
A few questions more.....
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?
John J. Dalton
12-27-2004, 11:40 AM
And more questions....lol
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.
John J. Dalton
12-27-2004, 11:50 AM
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
12-27-2004, 11:55 AM
Change the fan setting immediatelly!
“..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.
John J. Dalton
12-27-2004, 12:01 PM
ok...I'm going to switch the fan from auto to on