Humidifier problem
Humidifier problem
(OP)
Hello
I have an air handling unit with a new steam to steam humidifier. The humidifier is fairly basis and maintains the room level humidity set point pretty good. Only thing is it sometimes sets off the smoke alarm in the supply duct and even in the rooms. Any tips for getting residual steam / water droplets out of the air stream. We used to have HEPA filters on the unit with the old humidifier set up and never had problems them but they are now gone. Looks like the HEPAs took out not only dust particles but also water droplets. Any tips?
B
I have an air handling unit with a new steam to steam humidifier. The humidifier is fairly basis and maintains the room level humidity set point pretty good. Only thing is it sometimes sets off the smoke alarm in the supply duct and even in the rooms. Any tips for getting residual steam / water droplets out of the air stream. We used to have HEPA filters on the unit with the old humidifier set up and never had problems them but they are now gone. Looks like the HEPAs took out not only dust particles but also water droplets. Any tips?
B





RE: Humidifier problem
this can be either matter of adjustment or place of installation. there should be no sensible level of air drops too long downstream. setting too high? duct not insulated? many things are possible, and you should roll the sleeves and check one by one, beginning with manufacturers tips.
RE: Humidifier problem
RE: Humidifier problem
1) Put in a fast acting blocking valve that closes upon any AHU shutdown condition.
2) Change the control sequence. Typical humidifier control will alternate full flow and zero flow to maintain a return or exhaust air condition. The lag time in controlling the return/exhaust condition can make for hideous PID control.
Instead, reset the supply RH set point based on the return RH set point. If you want the space to have 30% RH for example, reset supply RH set point between 10 and 70% in the supply to maintain return RH.
In other words, if the space/exhaust RH is 5% RH below set point, have the supply maintain 70%. If the space RH is 5% RH above set point, have the supply maintain 10% RH. Reset the supply RH set point linearly between these two points.
RE: Humidifier problem
I'm asking for my own benefit here.
RE: Humidifier problem
The supply duct smoke (required per NFPA 90/92 for any supply system >2,000 cfm) should be as far as humanly possibly downstream of the humidifier.
RE: Humidifier problem
Even if you get the 9" throw and field conditions show it's actualy 12"; it there's 15" of space, I call that a win and a probable solution.
RE: Humidifier problem
RE: Humidifier problem
The wisp of steam entering the 42°F air might show an 8' vapor trail whereas the steam in contact with the 67°F profile has barely a visible profile.
If the bulk airstream were a perfect, uniform 55°F as designed, you'd see the uniform 9" vapor trail as promised... 90% of the time, this is not the case.
RE: Humidifier problem