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  1. #1
    Join Date
    Oct 2007
    Posts
    32

    Flow Through Humidifier: Cold vs. Hot line

    Just wanted to sart out by saying this site is awesome and has helped me greatly in the past! Lots of useful info and knowledgeable people here.

    Question:

    I was leaning towards the TruSteam humidifier, but I have a dual unit system and the expense for two of those is hard to swallow. So, I think I may go with the GeneralAire 1042 units. I've read on here that it's better to attach a flow through/bypass humidifier to the hot water line to achieve better/more humidity. My contarctor said that he prefers the cold line because of the scale build up in the unit and small lines that seems to happen when they use the hot water line. Is this accurate? Would I need to get a water softner, to solve this?

    Also, I read that the flow through systems aren't as efficient as the steam units and need the blower to run more to provide adequate humidity. My contractor said I can just leave the fan on to solve this problem if necessary. Would that really work.

    Thanks for your time!

    -Coop

  2. #2
    Join Date
    Nov 2002
    Location
    Lisle,Illinois
    Posts
    526
    I prefer the Aprilaire 600 series,hooked up to the hot water to improve evaporation 20%.The Aprilaire will be easier to find parts (pads etc,) for as any contractor will have them in their truck.Also the 600 is more water efficient.
    Ethics are as important as education.

  3. #3
    Join Date
    Dec 2005
    Location
    St. Louis
    Posts
    17
    I agree with hvacmd the aprilaire is a better unit. I also use the hot water line, but install an inline scale inhibitor.

  4. #4
    Join Date
    Oct 2007
    Posts
    32
    Would the Aprilaire 600 series be overkill since I need two due to my dual system? My house is approx 3150sqft.

    Also, does the Aprilaire come with a humidistat or the like that controls the blower when the furnace isn't running? (I'm not sure if the Generlaire does or not)

    I'd still like to know if manually running the fan when the furnace is not cycling will work to increase the humidity. Thanks for the help so far, all.

  5. #5
    Join Date
    Sep 2007
    Location
    southern IN
    Posts
    527
    I would think it would be overkill. If you need two anyway I would go smaller and by-pass. Less parts to fail and should provide adequate humidity. I use to use hot water till the trainer from Honeywell advised it doesn't actually help.
    The other interesting info is it takes 4 gallons of water to put 1 gallon in the air with by-pass 3 to 1 power.

    Don't know about the controll,we use honeywell. there are humidistats that can, have your contractor let ou know what they normslly use.
    The first man gets the pearl, All the second gets is the shell

  6. #6
    Join Date
    Nov 2005
    Location
    Linn Creek, Mo
    Posts
    399
    Quote Originally Posted by polvo View Post
    Would the Aprilaire 600 series be overkill since I need two due to my dual system? My house is approx 3150sqft.

    Also, does the Aprilaire come with a humidistat or the like that controls the blower when the furnace isn't running? (I'm not sure if the Generlaire does or not)

    I'd still like to know if manually running the fan when the furnace is not cycling will work to increase the humidity. Thanks for the help so far, all.
    You could go with 2 of the AprilAir 500's. They are the same as the 600's, just a little smaller.

    I hook all humidifiers up to hot water. Out of all the humidifiers that I service, the ones hooked up to hot water has alot less scaling than the ones hooked up to cold water.

    As for running the fan manually, you have to have the humidifier hooked up to hot water. If you have it hooked up to cold water, then you have to only run the humidifier when the furnace runs. If you run the fan all the time, then it will humidify when ever it needs to. I it is hooked up on cold water and only run when the furnace cycles, then it only humidifies when the furnace runs which means you get a lot less humidity due to the short furnace cycles.

  7. #7
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    I have my aprileAire model 700 ducted into my return drop and the hot water tap connected because I hace it on my return drop, but if your have the ducted into the supply side I don't see any problem with the water supply using cold tap. You should be able to hook up the Aprilaire one of 2 ways, one is to run when the blower run for a heat call, or have the humidifer run whenever theres a cal for humidity when you have yoru blower fan running 24/7 which is how I have mine set up and works nice. Running the blower 24/7 also helps to keep the ID temps evenly thru out the house.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,876
    Hooking up to the hot water improves the humidifiers ability to add moisture to the air, weather its hooked to run only during heat calls, or when ever the humidistat calls.

    2 600s, or 500s should be more then enough to handle your house if hooked to the hot water line.

    I would connect them to the hot water, and set them up to run when ever teh humidity is low.
    With 2 systems, one may not run much, so if set up to only operate on a call for heat. The furnace may not provide enough run time.
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  9. #9
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,895
    Stay away from Aprilaire, their a bunch of instigators!

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    " Kill a Commie for Mommy! "

    - Colonel David Hackworth (1930-2005), Korean War Vet

  10. #10
    Join Date
    Oct 2007
    Posts
    32
    There seems to be some debate over the Aprilaire vs the Generalaire. Some people prefer the Aprilaire, others say the Generalaire is pretty much the same unit. Is there an advantage or extra level of control that the Aprilaire has over the Generalaire that I'm missing?? Thanks

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,339
    Hooking up to the hot water line makes you feel warm, but how much warmer is the small amount of water that is delivered to the humidifier? At the low flow rate, 1 gallon per hour, the water kools to ambient air temp before reaching the humidifier! Cooling from 125^F to 70 is 660 btus of heat for the hour. To evaporate 8 lbs. of water per hour take 12,600 btus of heat. Considering the little bit of possible heat from hot water, forget the advantage of hot water. Its a myth. To confirm fell the temp of the water line reaching the humidifier. If the water tube is warm, you are over-feeding the humidifier. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  12. #12
    Join Date
    Oct 2007
    Posts
    32
    Some say hot, some cold...

    Some say cold = scale build up, some say hot...


  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,876
    Aprilaire feeds a lot more then 1 gallon an hour to their 500, 600, and 700 models.

    And using hot water improves their evaporation rate.

    If they only fed 1 gallon an hour. They wouldn't be able to add much moisture to the air.

    From Aprilaire.

    Should our humidifier be connected with hot or cold water?

    All of our flow-through units can be connected to hot or cold water. Hot water increases the evaporative capacity of your humidifer, provides more humidity to the home and offers more flexibility in the operation of the humidifier. Some of our units can use hot air and cold water. All humidifiers need some source of heat for evaporation to take place whether it is hot water or hot air. We would recommend that if our power units are installed on the return ductwork, that they be connected to hot water, as this is their only heat source. Heat pumps and large capacity installations need hot water. Heat pumps are not hot enough for evaporation and some larger installations need maximum capacity so they will need to use both hot air and hot water. The Model 400 should be connected to cold water due to the wicking Water Panel as it cannot be guaranteed that the water will stay hot while waiting for the next heat call on the Water Panel. With any drain-though Aprilaire Humidifier connected to hot water, the heat in the water is used in the evaporation process and the water coming out of the drain will be cold to the touch.
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