cooling a small server room

[serverroomcooling]

I also want to add a third supply vent....one return is good....it'll pull all the hot air out from behind the servers

[john dalton]

Dear Serverroomcooling,

Regarding your posted questions:

“I forgot what a HGB does, can you refresh my memory????”

A hot gas bypass maintains a minimum PSIG rating downstream of the valve outlet (usually located between the TXV and the evaporative coil distributor). This will prevent the evaporative coil from freezing under almost all normal operating conditions.


”OK...the unit he is referring to is the original 1.5 ton that died, not the Trane I put im...the one he is referring to in in my drop ceiling...the Trane is on the floor inside the room “

Completely understand.


”I'll mention to him that the unit is only 4 ton....maybe that is just a typo.”

Could be, Lord knows there’s been quiet a number of mistakes as of this date…..lol.


”I emailed him about the heat load....I don't think I'm going to get one...”

Because?????????????????????


“…but I'm adding about 5000 btu as soon as I can after the installation....how do I know if what I have is oversized or if it is the right size...”

That’s easy……you don’t!


“….if it is the right size, and I'm going to add 5000 btu that would bring me up to 3.5 ton...”

Is the 5,000 BTU sensible heat, latent heat, sensible and latent heat,,,,,,,,,,,,How do yoy know it will bring you to 3.5 tons….we have NEVER seen any heat load on this project and you have yet to test it under the worst conditions(three day holiday in July or September).


“...is an extra ton going to hurt my room???”

How do you know you have an extra ton???????


”…can I do my own heat load test?”

No.


“At this point, I really don't want to go through more waiting and wondering when it's going to happen...I need to get this thing in so I can get my new equipment in and begin on my other projects”

I can understand your point of view……..

In conclusion, without a documented heat load, you simply have no way of knowing what you have….period!

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

Regarding your posted question:

”…can I do my own heat load test?”

My original answer was a flat no….and that still stands in respect to doing an accurate engineering survey of your system….but:

You could do an estimation of a heat load. It would not be a conventional professional computer generated engineered survey; it would be more in the lines of an actual field test. To do so, you would need to wait until you had a very hot day with the buildings HVAC system off, the steps would be as follows:

1. Determine that the existing HVAC system for the Server Room was working correctly and to full capacity.

2. Perform the test on a Monday after a hot weekend with the building’s HVAC system off.

3. Monitor the cycling off and on rate of the HVAC system from 12:00 noon to 8:00 PM on this Monday.

4. Obtain a percentage of on vs. off time and multiple that percentage by the rated tonnage of the system. If the system continues to cycle off and on throughout the monitored test time, then this would be a good estimated heatload for that outside temperature. If on the other hand the system stopped cycling and continued to run while the inside Server Room’s temperature elevated, then the heat load of this project is higher than the rated capacity oif the existing HVAC system.

In conclusion, if you could get the monitoring completed during an extremely hot day(such as 100 to 105 degrees F) then you would have a good estimation of the actual heat load of the project.

Respectfully Submitted,
John J. Dalton

PS: As you can see, this test would not be the easiest to complete….but so far the computer generated heat load has been impossible to get…..think about it.

[serverroomcooling]

I'm guessing there is software out there that can do it for me...maybe I'll find a demo that will work for a couple weeks....

I'll ask for a heat load

[serverroomcooling]

and BTW....I was joking about thre HGB, of course I remember what it does

[john dalton]

Dear Serverroomcooling,

As for finding and running a program by yourself…..DON”T! This thread would double in size almost immediately in trying to answer your countless questions.

Leave that one for the professionals.

Respectfully Submitted,
John J. Dalton

PS: good one about the HGB…..lol

PSS: Why don’t you think you’ll get a generated heat load? This information is the Clients when they accept a project. Unless he has something to hide, like he didn’t run one, just guessed at it.

[serverroomcooling]

he took info on my room initially...I sent him the room size and the wattage of all the equipment.....I assume he did a heat load....the guy who put in my Trane gave me a heat load....it was generated in an hvac application, I got a demo of it and opened the file, but had no idea how to read it.......

what's wrong with tripling the size of the thread....don't you want this to be bigger than the 9mm thread, this one is so much more informative!!!

[serverroomcooling]

I have 2 files, a .dbp and .rhv

dbp seems to be linked to an external database so it was useless to me, but the rhv opened in an appllication I found on some hvac site. There was a demo and I used it....couldn't make much out....can you open it? I'd gladly email it to you for your review....it was actually done by a different company, not the Trane guy. I used the Trane guy b/c he works in the building and could get the job done right away without any building problems

[serverroomcooling]

my copy of the hvac calc still works....I'm going to play around with it....I promise not to ask questions....

the calc comes from elite software it's called RHVAC, which is probably residential hvac, so it will probably not even be the right one for me

maybe I just wom't waste my time and stick with my elemetary appraoch.....gather my AMPs, convert them to volts, then to BTU, figure out a good guess for my changing enviornment due to building AC going on and off and heat from building rising...and go from there...not the best appraoch, but I don't feel like pressing this guy for a heat load test

[john dalton]

Dear Serverroomcooling,

Regarding your posted question:

“maybe I just wom't waste my time and stick with my elemetary appraoch.....gather my AMPs, convert them to volts, then to BTU, figure out a good guess for my changing enviornment due to building AC going on and off and heat from building rising...and go from there...not the best appraoch, but I don't feel like pressing this guy for a heat load test”

It’s thinking like this that got us where we are today….without an accurate heat load.

I have a saying: Either do it right or don’t do it at all….period!

But…..your time is your own my friend.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Serverroomcooling,

You never answered my question as to why you hesitate about asking for his heat load calculation?

Respectfully Submitted,
John J. Dalton

[serverroomcooling]

I have asked and asked and asked.....apparently these guys down here don't give out heat load tests to clients, or don't do them at all. If I was a huge account they would do it in a heart beat...I have asked him for a heat load time and time again, just never got one from him

[hvac-tech-lane]

"1” standard filter" ? What size? 2300 CFM hope its huge, I would prefer a 4" pleated filter.
"Spot water detector & local alarm " Not very useful unless located in a pan or within a containment angle, check into cable leak detection if you want to cover your bases.

[seaboard]

Originally posted by serverroomcooling
I have asked and asked and asked.....apparently these guys down here don't give out heat load tests to clients, or don't do them at all. If I was a huge account they would do it in a heart beat...I have asked him for a heat load time and time again, just never got one from him

If you haven't awarded the job yet and have no investment with them I'd also be hesitant to hand over the load calculation...for free. You seem to like these guys alright and you haven't had any luck with anyone else. Ask them for a letter of intent and agree to pay some engineering fees for the time they have invested if you walk away. If you proceed with the proposal you owe nothing.

[serverroomcooling]

these guys at least came through with something....I think it won't be reckless to just trust them

[tawnhb]

Just to site one mistake u do is , suppose your room dont ever ahve the pc - server, normal cooling load of 3.5kw (--ton) per normal room may be needed, very roogh -say bedroom size. So u simply ignored structural heat gains, so back to basics, u have ignored other contributing loads, and approach someone or revise your calaculation.

[serverroomcooling]

I can't imagine that this nominal 4 ton unit isn't a decent fit for my room.....but I'm no expert....I just can't go after more and more hvac companies....even the local Liebert rep never came back to size my room with a system, don't know why, just think the economy is obviously so good these days that companies don't need business with long term maint contracts connected to them. I offered him the job as soon as I got funding, never heard from him...he did send guys in who took all the "calculations" just never heard from them.....this is so incredible frustrating....

80 pages and no one from the South Florida area has seen this thread and wants my business?????

[thehumid1]

Originally posted by john dalton
Dear Serverroomcooling,

Regarding your posted questions:

“I forgot what a HGB does, can you refresh my memory????”

A hot gas bypass maintains a minimum PSIG rating downstream of the valve outlet (usually located between the TXV and the evaporative coil distributor). This will prevent the evaporative coil from freezing under almost all normal operating conditions.


”OK...the unit he is referring to is the original 1.5 ton that died, not the Trane I put im...the one he is referring to in in my drop ceiling...the Trane is on the floor inside the room “

Completely understand.


”I'll mention to him that the unit is only 4 ton....maybe that is just a typo.”

Could be, Lord knows there’s been quiet a number of mistakes as of this date…..lol.


”I emailed him about the heat load....I don't think I'm going to get one...”

Because?????????????????????


“…but I'm adding about 5000 btu as soon as I can after the installation....how do I know if what I have is oversized or if it is the right size...”

That’s easy……you don’t!


“….if it is the right size, and I'm going to add 5000 btu that would bring me up to 3.5 ton...”

Is the 5,000 BTU sensible heat, latent heat, sensible and latent heat,,,,,,,,,,,,How do yoy know it will bring you to 3.5 tons….we have NEVER seen any heat load on this project and you have yet to test it under the worst conditions(three day holiday in July or September).


“...is an extra ton going to hurt my room???”

How do you know you have an extra ton???????


”…can I do my own heat load test?”

No.


“At this point, I really don't want to go through more waiting and wondering when it's going to happen...I need to get this thing in so I can get my new equipment in and begin on my other projects”

I can understand your point of view……..

In conclusion, without a documented heat load, you simply have no way of knowing what you have….period!

Respectfully Submitted,
John J. Dalton

LOl not this again but....Some are installed on the discharge right after the compressor...

"(usually located between the TXV and the evaporative coil distributor)."

But not to misquote you.... as you did say " usually"

[john dalton]

Dear Thehumid1,

Regarding your post:

LOl not this again but....Some are installed on the discharge right after the compressor...
"(usually located between the TXV and the evaporative coil distributor)."
But not to misquote you.... as you did say " usually"

Sorry for the confusion, but I assumed everyone knows that ALL hot gas bypass methods begins between the discharge of the compressor and the inlet of the condensing coil, it’s where the outlet is located that differs. As I stated, it’s usually between the TXV and the evaporative coil distributor.

Again, you didn’t misquote me, you just quoted me out of context.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Thehumid1,

Regarding your post:

“…Some are installed on the discharge right after the compressor... “

Actually it’s not some, but its ALL HGB methods begins from between the discharge of the compressor and the inlet of the condensing coil, hence the term…..HOT GAS.

Quoting your exact words and in context my friend…….your move.

Just love a great game of HVAC chess.

Respectfully Submitted,
John J. Dalton