Best humidification method?

Dennis Kunkle

Our museums are combining and moving to a brand new facility. Currently we have two Nortec gas fired humidifiers that I'm basically tired of servicing. What do you folks consider your overall favorite type of humidification?

ratio

I installed two sets of IIRC 90 gal/h twinned electric Nortec units a few years ago. The plain relay-controlled model, not the modulating SCR style. Near as I can tell, they worked just fine. The owners refused to perform maintenance on them, The first time I was sent out for 'warranty', I took 20(!) lbs(!!) of scale out of *each* *one*!

Dennis Kunkle

What I'm looking for is anyone's experience with other methods of humidification. If we had been paying for professional PM on our units, along with parts replacements (igniters, fill valves, etc.), the Nortecs would have been very expensive to operate. So what about other methods? Misting, Electrostatic(?), etc.

ratio

I just recalled, in one of Dan's books, he talked about putting a sacrificial hot water heater in the feed to a boiler used for process steam. Might be something to look in to.

Jean-David Beyer

In my house, I use an AeroSwiss boiling water type machine, but that just does my bedroom. It has enough capacity to do a little more.
When I was researching these things, there seemed to be three types. Type 1 use ultrasonic transducer to generate a fog without heating the water, and a fan to blow the fog around. You do not actually see the fog. This works and is probably energy efficient, but since the water has not been boiled in the unit, you may wish to ensure it is sterilized somehow. Also, if you are not using distilled water (and why would you?), the fog eventually deposits the boiler scal all over the room as dust. You may not like this.

Type 2 uses a pad that is soaked in water. Either the water just wicks up into the pad, or a small pump dumps it in from above. Then a fan blows through the wet pad and the evaporated water is circulalted through the space by a fan. Some friends have a unit like this big enough for their house. But they never use it because they hate filling it up, and the fan is too noisy. You must use something in the water to keep the bacteria at bay, and the pads clog with scale.

Type 3 uses a boiling mechanism and lets the steam escape into the conditioned space. Mine has a tiny slow-moving fan to run air through it whenever it is on. If the heater is turned on, the fan runs a little faster. You need not sterilize the water. A little pad is in there that absorbs most of the scale, and you clean the actual boiling surface by soaking in in a cleaning solution. I have to do this every couple of weeks. It has a big reservoir (1 to 2 gallons, I guess), but it does not heat the whole thing. A little feeds onto a hot plate like a chicken watering device, and only the little bit is heated.

I guess there is a type 4. I was responsible for a computer room
that needed to be air conditioned to any temperature, but held with a 2F range. We did humidify that in the winter and dehumidify it in the summer. For the humidifier, there were three CalRod heating units in a tub inside the AC unit. When humidity was desired, power was put into the three calrod units and this boiled the water. There was a city water line going into the tub through a toilet tank fill valve that was delicately adjusted so that when the heat was not on, the tub was filled up to the very top of an overflow standpipe (that went to a drain) so water did not overflow. But when the calrod units were boiling the water, there was a slight overflow down the drain that took most of the deposits out before they precipitated out. We had to clean the calrod units only about once a year.

Where I used to work, in a building that ultimately held about 18,000 employees on six floors, they injected steam from the boiler room into a mixing boxes. The mixing box was supplied with cold air and hot air and the thermostat adjusted the ratio between those so the room was at the desired temperature. Hygrostats adjusted the steam valve for the humidity. The plant department made sure the water treatment in the boilers was done correctly. Those thermostats were pneumatic, not electric.

EBEBRATT-Ed

All humidifiers will scale up especially if using plain water.
They do have a compressed air system that use air to mist the water into the air. The cost of operation is in the compressed air. It also cools the air by abdiatic cooling which would help in the summer(reduces load on cooling plant)