Problem on flooding at AHU Room
Problem on flooding at AHU Room
(OP)
I'm having a problem regarding flooding on the AHU Room, where in we have installed two (2) Packaged Water Cooled Units in a single room.
Water comes out from the floor drain as a result when we run the two units at the same time.
Is it possible that excessive return air can contribute to the flooding? We have installed the 2 units and its individual return air as a plenum return (the whole AHU Room being its plenum box).
What can be done to minimize this?
By the way the room is fully insulated.
Thanks.
Water comes out from the floor drain as a result when we run the two units at the same time.
Is it possible that excessive return air can contribute to the flooding? We have installed the 2 units and its individual return air as a plenum return (the whole AHU Room being its plenum box).
What can be done to minimize this?
By the way the room is fully insulated.
Thanks.





RE: Problem on flooding at AHU Room
RE: Problem on flooding at AHU Room
Sound like the system needs a good looking at.(commissioning being a key requirement)
What sort of units are they?
Floor mounted top discharge, Floor mounted downward discharge into a suspended floor?
Whose make are they.
Can you turn the extract down (If there is any)
If you are sucking water out of the drains, I would guess that the drains are 'trapped' with a 2" seal.
If so, to pull the water out would need 500Pa of suction...some negative room pressure. I'm surprised the walls haven't caved in.
Have you checked if the drain is blocked, laid to a suitable fall etc.
Friar Tuck of Sherwood
RE: Problem on flooding at AHU Room
However, reading carefully you seem to be saying that water is coming out of a floor drain in the room. Could you clarify this please.
If you are actually sucking water out of the drain line it is probably because you have high negative pressure in the room. Possibly leaks in the return ducting, or possibly a service access panel left open.
RE: Problem on flooding at AHU Room
When you say flooding is water continually coming up from the floor drain, if it is it doesn't sound like condensate (unless your mixed air is at 90% RH).
RE: Problem on flooding at AHU Room
the OP states he has a sealed room, as return air plenum.
Most likely the relative low room pressure (-) is drawing waste water from the trap into the plant room. Incidentally, that is how SARS outbreak occurred.
Anyway solutions:
- unseal the plenum
- increase the depth of the trap seal [such that the water seal is greater than the negative pressure created in the plenum]
If you have trap top-up devices, check that it is operational.
RE: Problem on flooding at AHU Room
1. Ensure that air pathways (return and make-up) are not obstructed by wall construction or faulty dampers.
2. The floor drain needs to be properly sized, trapped, and ideally, a trap primer would be used to keep from drawing in wastewater gases.
RE: Problem on flooding at AHU Room
I'VE FOLLOWED ALL YOUR SUGGESTIONS, I ALSO MADE TRIAL AND ERRORS, I'VE COMBINED SOME OF YOUR SUGGESTIONS AND IT WORKED ON SOME AREAS USING THIS KIND OF SET-UP.
WE MANAGED TO MINIMIZE THE BACK FLOWING OF WATER FROM THE DRAINS, BUT STILL SOME AREAS ARE HAVING THE SAME SITUATION.
BY THE WAY, THE FLOOR DRAINS ARE CONNECTED IN ONE COMMON DOWNSPOUT 8in Dia. AND THE ROOM DEFINITLY ACTS AS A MIXING CHAMBER.
THANKS TO ALL.
RE: Problem on flooding at AHU Room
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