Denco Units in Computer Room.

[Henry1]

Hi Guys,

Any ideas much appreciated, we have a computer room at 103sqM, cooled by three Denco D74 units, in turn fed by two York air cooled Liquid Chillers, we number them 1 to 3, now the problem is that number 1 seems to be providing the full load for the room!! i can work on 2 or 3 with only a few degrees lost, if i turn off #1 the temp goes through the roof, the room has 36 servers in it, i have conflicting information, on site O&M manuals state each unit gives 91.36kW Duty, Denco say 61.3kW Duty?? im going with Denco, they recon two units can comfortably control room at 21Deg, so, what am i missing with #1.

Hope my written words and brain have kept up with each other, any questions please ask.

Thanks.

[hyperion]

It would appear that the #1 unit is providing the temperature control and then bringing on #2 &3 as slave units if the temperature rises. There may be a way of changing the lead unit and temperature control. Denco should be able to advise if this is possible.

[Henry1]

Hi Hyperion,

That would be a great reply, but the units were never linked!!! (i know) all three run 24-7, this is why in five years all of the fan and motor units have been replaced not to mention fan belts, also might be worth mentioning that there is no ducting from each unit under the floor, they just blow out into the room from one wall, if you lift a floor tile on the opposite wall there is barely any air flow, still comes back to why one unit carries all three.

[hyperion]

This would possibly suggest that the effective cooling duty of units #2 & 3 is not the same as unit #1.
If they are all the same model then this unlikely but still possible. Are the water flow control valves opening fully on units #2 & 3?
Are the fan belts/pulleys the same on all three units? Is the fan rpm the same? Are there any restrictions in the discharge ducting from units # 2 & 3?
Is the server heat load evenly spread or is it nearer to unit #1?

[Henry1]

I think the whole room is a mess, for starters they are not CRAC units, they're just air blowers, there should be units on opposite walls not just one, they think they have hot cold isles so why have floor grills on both sides of the servers, and the extract grills are at eye level instead of max hight, the company that designed this should be shot, All are the same model, water flow control fully opening, rpm the same discharge ducts ok.

[hyperion]

Provided that the chiller is supplying water at the correct flow temperature, ie 8degC and the design of the air distribution suits the area, then the Denco units should be capable of cooling the room efficiently. There must be some other fundamental that is not correct.

[The Viking]

Air in the coils of No 2&3?
Diverting valves in the right position?

[Brian_UK]

Have you checked the water flow rates through the three coils?

[install monkey]

sort out ur belts,clean coils and replace filters, clean inpellor blades, ensure floor is sealed execpt for under cabinets, calibrate return air sensor, ensure full travel of 3 port actuator ie 100% open, also no strainers in system, pressurisation unit is at 1 bar minimum, pressure relief valves arent passing, and as others said , air in system- maybe lower chilled water setpoint, clean any strainers, and check the buggers havent whacked a load of new servers in- check for any fresh air ventilation- free cooling is good this time of year
good luck

[r.bartlett]

This needs a fresh pair of eyes to see if there is anything obvious..

air on/off
air flow (fan rotation)

post some pic's if they allow.

[install monkey]

lack of maintenance!- how can you check rotation of a fan from a piccy richard? haha- surely airflow fail alarm should be present!

This needs a fresh pair of eyes to see if there is anything obvious..

air on/off
air flow (fan rotation)

post some pic's if they allow.

[r.bartlett]

lack of maintenance!- how can you check rotation of a fan from a piccy richard? haha- surely airflow fail alarm should be present!

with my million dollar man eyes I can also tell air on/ off temps just by looking at a picture....(but only if there is a thermometer showing)

[Henry1]

Hey guys, thanks for all the great ideas, everything is and has been checked, i have an Airflow company in over the weeklend, as i said IT think they have a hot cold room no matter how many times i tell them it isnt, you would think they gave birth to this room the way they protect its faults, by the way they laid the grills either side of the servers, and maintenance is nigh on impossible as they never give permission to shut the room down as its the Data Centre for a well known (if your not in it you wont win it) company. I'll let you know next week if anything has improved.