Water Blow-Off During Humidification 3

[BMitch]

We are getting excessive water build up under one of our DATA AIRE CRAC Units (model# DAAD-2034)during humidification (the humidifier in the CRAC Unit is a Nortec MES-U series). We have changed out the cylinder which helped a little; have also checked the drain line, which is clear; and the Capacity Pot is turned down as low as it can go (25%). I believe the issue is more of a design flaw, the steam is distributed (or dumped) to just one of the two blower fans causing water to build up in our sub-floor. Any ideas or suggestions are appreciated.

BMitch

 

[sridhar1312]

Check the air quantity as most of the time estimated static may not be there making air flow more thus velocity across cooling coil will be high making the water carry over.

Best is to measure the air quantity and adjust the fan speed by changimng the Motor pulley of the air handler.

 

[willard3]

Find a Mechanical engineer and pose the problem to him as this is problem that won't be solved on a web forum.

 

[BMitch]

sridhar1312,
The air speed in the CRAC (Computer Room Air Conditioner) is ok. There are two blower fans and water is only coming out of the one that the humidifier's steam dispenser is connected to and only leaks when the humidifier is on.

BMitch

 

[BMitch]

willard3,
We did call out our Mechanical contractor and he is stumped. Other than redesigning the factory built steam distribution system they do not know what to do. Our Mechanical contractors have a lot of experience with CRAC units and Data Center cooling but are new to Data Air CRAC units.

BMitch

 

[tys90]

Just to be clear, is the issue that the steam is not being fully absorbed into the air stream when the humidifier is on? And water is collecting downstream of the fan? Is the steam collecting on the fans and then being blown downstream?

Without knowing very much it sounds like your absorption distance for the humidifier is too short and it's condensing on some surfaces and getting blown through the fan.

 

[ChrisConley]

What is the distribution manifold like? Most manufacturer's have Short, and Extra Short distribution manifolds which shorten absorption distance greatly to prevent carryover.

 

[BMitch]

tys90,
Yes that is my guess.

ChrisConley, tys90,
I have attached pics that show the blower fan and steam distribution manifold. The first pic shows the manifold size, about 8in (the blower fan is 14in); and where water is building up on the inside of the fan housing.

 

[BMitch]

Here is one more pic:

 

[ChasBean1]

BMitch, for the humidifier, there's a capacity potentiometer (see attached) with a range of 20-100%. What is this set to? If it's high, may want to try reducing it way down for more steady humidification and less cycling. In a data center, air exchange is usually very low; very little added humidity should be necessary.

Other note: the larger copper pipe appears to have the disch. nozzles so the smaller pipe would be the drain back to to the cylinder? Looks like the drain line opening would be very small - could try a blast up the drain line with compressed air to dislodge anything stuck in there.

 

[BMitch]

ChasBean1, the Capacity pot is turned all the way down to 25% (the lowest setting). We checked the resistance of the potentiometer set at 25% compared to our other Data Aire Units potentiometers set at 25%; They were only off by 1/10th of a K Ohm. We also verified that the drain line is free of debris.

 

[tys90]

You need to get the steam distributor out of the fan. That steam is never going to absorb into the air stream, it's getting blasted into the fan housing and condensing on the surfaces and getting blown all over it from the looks of the picture. Put it downstream in the duct work that has sufficient straight length of duct work to absorb properly.

 

[ChasBean1]

Agree - if it can be placed above the cooling coil in a place that would allow any leakage to be caught in the drip pan, that could help. How old is the unit? This seems like it should be the manufacturer's/vendor's issue to correct.

 

[BMitch]

Tys90, We have four other Data Aire units (same model) that are not having this issue. I agree we may need to move the steam distribution manifold but are looking into other options before changing any factory specks. Also, we can not move it downstream, we do not have any duct work connected to our CRAC units. The CRAC units blow air into a plenum (our sub-floor) where all power and communication wiring is ran, which is why the water is a big issue.

 

[Compositepro]

It looks to me as though there is water being sprayed out of the manifold with the steam. Is the water drain oriented correctly to keep water out of the spray holes. The drain must be almost exactly on the bottom so there is no paddling in the manifold. The manifold should be insulated to reduce condensation inside the manifold which appears to be copper and in a very high air velocity. That's a good condenser design if you wanted to heat the air rather than humidify it.

 

[BMitch]

Compositepro, The drain is on the bottom of the manifold. I will speak to our Mechanical contractors about insulating the manifold and see what they think.
I'm not sure what you meant by "That's a good condenser design if you wanted to heat the air rather than humidify it.", could you elaborate.

 

[tys90]

I was unaware that this was the only one having this problem. Is this the standard location for these steam humidifier manifolds in CRAC units? It seems to be about the worst place you could put a humidifier - high air velocity and very close to surfaces it can condense on.

 

[CountOlaf]

Sounds like it might be time to contact a service rep from Data Aire. It could be other components associated with the steam generator not working right. I wonder if that unit could be retrofited with the infrared lamp type?

 

[BMitch]

Tys90, This is the standard location of the manifold on all five of our Data Aire CRAC units. The other Data Aire units also have this issue but not as bad, once the humidifier shuts off the small bit of water that has collected is dried up within a minuet. All settings on the five units are the same.
We also have Liebert and AirFlow CRAC units. The AirFlow (this company no longer exist) units have similar a humidification design but the steam is distributed into the blower section of the unit,not into just one fan. This allows the fans to pull steam into the supply air, these also work well but are now are rusting out. The Liebert units use a humidifier pan with an infrared bulb, which works very well.

BMitch

 

[BMitch]

CountOlaf, The Data Aire Technical Support has not returned my calls or replied to my emails in over a week, I think they don't want to admit the pore design. Problem is, at this 24/7 critical facility I don't have time to just wait around so i am trying to find ideas elsewhere.

BMitch