Page 1 of 2 12 LastLast
Results 1 to 13 of 23

Thread: Desiccant Wheel

  1. #1
    Join Date
    Mar 2004
    Location
    Minnesota
    Posts
    38

    Hmm

    I am looking for some information on a good Desiccant Wheel to help remove mositure from a testing lab here in Minnesota. We are having trouble keep a handle on the humidity level in the summer months. We have three chillers along with three steam boilers that run year round. I am working on changing the program (energy management) to open the heating valves before the cooling coil to help remove so moisture; but is taking a lot of energy and not able to keep a handle on the system yet. This building runs 24/7 so you would think that one could get in the ballpark. But the levels bounce all the up to 75% on a rainy day! Any info would be very much welcomed. GD

  2. #2
    Join Date
    Mar 2004
    Location
    Austin, Texas
    Posts
    1,959
    ASHRAE's book Humidity Control Design Guide is a good place to start. I can't recommend that book highly enough. For desiccant manufacturers, try Munters & Bry-Aire. There are probably more but those are the ones I have seen.

    Be warned, desicant wheels as energy recovery ventilators (ERV) will do little to help your situation. Those are actually "load reduction devices" instead of humidity control devices.

  3. #3
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,270
    Originally posted by the good doctor
    I am looking for some information on a good Desiccant Wheel to help remove mositure from a testing lab here in Minnesota. We are having trouble keep a handle on the humidity level in the summer months. We have three chillers along with three steam boilers that run year round. I am working on changing the program (energy management) to open the heating valves before the cooling coil to help remove so moisture; but is taking a lot of energy and not able to keep a handle on the system yet. This building runs 24/7 so you would think that one could get in the ballpark. But the levels bounce all the up to 75% on a rainy day! Any info would be very much welcomed. GD
    Wheels work well when dry exhaust air is routed through the wheel with wet fresh air also routed through the wheel. 50% of the moisture transfers from the wet to dry air. Using reheat requires the heat tobe added down stream from the cooling coil. Also the water chiller must have very cold water to be effective. Also consider free standing dehumidification for short term solution. Look at the Hi-EDry 195 at thermastor.com. These units are used in water treatment plants throughout MN to maintain less than 55^F dew points. These dehumidifiers generate some reheat as part of the dehumidification process.

  4. #4
    Join Date
    Aug 2003
    Location
    Ft Worth Tx ( North Richland Hills)
    Posts
    2,143
    Munters makes a very high quality air handler and desiccant wheel system. At the museum where I work we have photography archival vaults where photos and negatives up to 150 years old are preserved. Humidty control is critical. One vault we keep at 30% and the other at 40% and have had very good success and reliability with the Munters equipment.

    Contact them at their factory (Located in Amesbury MA) ask for Engineering/sales 978-241-1100
    How can you have any pudding if you don't eat your meat?

  5. #5
    Join Date
    Aug 2004
    Location
    Currently in Phoenix, AZ
    Posts
    31
    Shameless plug: Visit http://www.semcoinc.com and click on "desiccant wheel products". Cxagent is correct as concerns energy recovery ventilators, however, we have a complete line of custom air handlers that incorporate our desiccant wheels. We also sell just the wheel as well if you are looking to incorporate it into your existing system.

  6. #6
    Join Date
    Mar 2004
    Location
    Austin, Texas
    Posts
    1,959
    Originally posted by cxagent

    Be warned, desicant wheels as energy recovery ventilators (ERV) will do little to help your situation. Those are actually "load reduction devices" instead of humidity control devices.
    I probably should have explained a little bit more. When the desiccant wheel is used to 'passively' recover energy from the exhaust air, it will transfer sensible and latent heat in the right direction to help reduce the heating/cooling load. However, it requires one of the streams (exhaust or intake) to be dry in order to reduce the moisture load in the building. If both streams are wet, the desiccant can't get rid of the moisture anywhere so it doesn't reduce the moisture in the building.

    A desiccant wheel with 'active regeneration' (gas or electric heat) can remove moisture very, very effectively. This takes energy to regenerate (dry) the wheel after it has absorbed moisture out of the building.

    Unfortunately, I keep seeing passive desiccant wheels installed and expected keep the building dry in all conditions. Once both indoors and outdoor air is wet the desiccant is loaded with moisture and moisture removal stops.

  7. #7
    Join Date
    Aug 2004
    Location
    Currently in Phoenix, AZ
    Posts
    31
    Absolutely true. At the risk of being frowned upon for doing too much advertising, let me just mention that SEMCO has a product called the "Pinnacle" which utilizes a dual wheel configuration in which the second wheel is a "passive dehumidification wheel" (it does not require any additional heat source like the active dehum wheels). This unit can provide outdoor air at a humidity level of 40 - 45 gr/lb using standard cooling equipment even under a partial load condition such as the good doctor describes (e.g. 85 db at 130 gr/lb). In MN I doubt that there are too many of those days anyway......

    Cx - you are obviously knowledgeable in this area, it might be of interest to you to have a look at this unit. Certainly any feedback would be welcomed. The most detailed description of this technology is here:

    http://www.semcoinc.com/website.nsf/Downloads
    Choose "Browse by product"
    Then "Desiccant Wheel Products"

    (I apologize for the huge list of literature, the piece to look for is titled "Pinnacle Series Technical Guide".)


  8. #8
    Join Date
    Mar 2004
    Location
    Austin, Texas
    Posts
    1,959
    Originally posted by the good doctor
    I am working on changing the program (energy management) to open the heating valves before the cooling coil to help remove so moisture; but is taking a lot of energy and not able to keep a handle on the system yet. GD
    Doctor -

    After rereading your post I have a question - Does the quote above mean that the heating valves open at an earlier time (before) the cooling coil? Or does it mean the heating valves open on a PREheat coil (air enters the preheat coil before the cooling cooling coil)?

    jchilling - thanks for the info. I didn't mean to exclude or slight Semco in any way. I just named two companies that came to mind first.

  9. #9
    Join Date
    Apr 2002
    Posts
    11,808
    Originally posted by the good doctor
    I am looking for some information on a good Desiccant Wheel to help remove mositure from a testing lab here in Minnesota. We are having trouble keep a handle on the humidity level in the summer months. We have three chillers along with three steam boilers that run year round. I am working on changing the program (energy management) to open the heating valves before the cooling coil to help remove so moisture; but is taking a lot of energy and not able to keep a handle on the system yet. This building runs 24/7 so you would think that one could get in the ballpark. But the levels bounce all the up to 75% on a rainy day! Any info would be very much welcomed. GD
    When you are dehumidifying you want to reheat the air after it leaves the cooling coil. Hopefully your heating coil is down stream of your cooling coil.

    The type of dessicant wheel you want would most likely be gas fired. The wheel would extract moisture from room then gets heated to drive out the moisture.

    People suggested Munters and Semco which are good sources. If you want some one good try http://www.masongrant.com and ask for Lew. He wrote most of the ASHRAE humidity control design guide. Tell him some guy from the Caymans mentioned him.

    I did a lab in Ontario. We had a custom packaged unit that over cooled air to dry it out, then had modulating gas heat to reheat the air.

    This lab was under positive pressure, and with all the outside air used, it required a special "Dri-Steem" humidifier in the winter to keep RH up.


    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  10. #10
    Join Date
    Oct 2002
    Posts
    970
    Originally posted by ozone drone
    Munters makes a very high quality air handler and desiccant wheel system. At the museum where I work we have photography archival vaults where photos and negatives up to 150 years old are preserved. Humidty control is critical. One vault we keep at 30% and the other at 40% and have had very good success and reliability with the Munters equipment.

    Contact them at their factory (Located in Amesbury MA) ask for Engineering/sales 978-241-1100
    Munters rocks... if you need air drier than a popcorn fart...it's the way to go..I have pic's to back it up..
    I work with the Chiller Whisperer...

  11. #11
    Join Date
    Mar 2004
    Location
    Austin
    Posts
    175
    Originally posted by ozone drone
    Munters makes a very high quality air handler and desiccant wheel system. At the museum where I work we have photography archival vaults where photos and negatives up to 150 years old are preserved. Humidty control is critical. One vault we keep at 30% and the other at 40% and have had very good success and reliability with the Munters equipment.

    Contact them at their factory (Located in Amesbury MA) ask for Engineering/sales 978-241-1100

    Hey ozone drone...I too am responsible for two archival photograph vaults. And I have four Munters, two in each vault, designed as redundant/lead/lag systems. I have never seen them work properly because the condensation builds up so quickly inside the unit, it actually rains on the circuit board and fries the board withing hours of operation. As a result, I have portable space dehumidifiers doing the job instead. I would be very interested in putting our heads together to come up with a solution.
    Def. of insanity: doing the same thing over and over again expecting different results!!

  12. #12
    Join Date
    Aug 2004
    Location
    Currently in Phoenix, AZ
    Posts
    31

    Hmm

    Cxagent - I didn't feel slighted in the least. I know that other companies come to mind first and I'd like to try and change that. I got a little carried away here and was too aggressive in my post.....

    Munters makes an excellent system also, no doubt about it.

  13. #13

    Dehumidification Only

    The best type of equipment for this application sounds like "liquid desiccant". See http://kathabar.com I have used these systems in surgical suite applications, food processing and pharmecutical plants. They are available in a wide range of sizes and are very effective. The ability of liquid desiccant to remove water vapor from air or add water vapor to air is determined by the temperature and concentration of the solution. Depending on the concentration, the conditioner delivers air at any desired relative humidity between 20% and 90%. This system allows air to be delivered at the required temperature and humidity regardless of air inlet conditions.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event