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  1. #40
    Join Date
    Nov 2004
    Location
    NJ
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    Quote Originally Posted by Poodle Head Mikey View Post
    But how could that ever happen?

    As I understand the control logic; the evaporator is maintained at 37. The speed and pumping capacity of the compressor would vary to maintain that temperature.

    The cold coil would seem to be maximizing the moisture removal while lengthening the run cycles.

    How can these units avoid providing great moisture removal? What performance dynamic am I overlooking?

    PHM
    ---------
    Pretty simple, the unit(s) were touted as being able control humidity like no other unit could. Both houses I was in had RH> 60% with dry bulb temps in the mid to low 70s. < 400 CFM PT.

    I put a bucket under the white pipe and got less than 6 pounds of water after an hour of run time.

    I was expecting > 10.

    Non-invasive test.
    Ed J

  2. #41
    Join Date
    Sep 2002
    Posts
    26,908
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    Oh; that's not very conclusive then.

    Maybe the coil setpoint was left at 47 instead of 37 ? Or maybe the airflow volume was too high for the building's heat gain? Or both. <g>

    I doubt they would out-dehumidify a Unico - with it's 32-33 six pass evap - but I would expect that when properly setup these Bosch's would be substantial performers.

    I keep asking about people's experiences with them because I have yet to install one.

    PHM
    ---------


    Quote Originally Posted by Ed Janowiak View Post
    Pretty simple, the unit(s) were touted as being able control humidity like no other unit could. Both houses I was in had RH> 60% with dry bulb temps in the mid to low 70’s. < 400 CFM PT.

    I put a bucket under the white pipe and got less than 6 pounds of water after an hour of run time.

    I was expecting > 10.

    Non-invasive test.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  3. #42
    Join Date
    Jan 2005
    Posts
    42
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    Quote Originally Posted by Poodle Head Mikey View Post
    Oh; that's not very conclusive then.

    Maybe the coil setpoint was left at 47 instead of 37 ? Or maybe the airflow volume was too high for the building's heat gain? Or both. <g>

    I doubt they would out-dehumidify a Unico - with it's 32-33 six pass evap - but I would expect that when properly setup these Bosch's would be substantial performers.

    I keep asking about people's experiences with them because I have yet to install one.

    PHM
    ---------
    What was the problem with the bosch unit in the end? Faulty control board?

  4. #43
    Join Date
    Aug 2019
    Posts
    1
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    Hey guys, new to the board here but I have found the exact same thing..... it's tough to find info on these bosch systems. I had a unit installed about a month ago and just wasn't happy with it. It's a 3 ton, 96% split dual fuel propane unit. My dad was in HVAC for 45 years so I've got enough knowledge to be dangerous and knew something wasn't right. The house was set on 72 and wouldn't hold less than 75 of 76, but didn't matter if I set it on 74, would hold about 3-4 deg above. So I called a friend and had him come take a look, the adaptive cooling is now on as well as the accelerated cooling. At the present time the Honeywell thermostat is set to adaptive cooling as well. We found that the installer didn't hook up Y2 from the honewell THM5421R communication board inside to the Y2 on the furnace. Once we did that and turn the option on for the Honeywell TH8321R1001/U thermostat to a 2 stage cool, it gave power to the second stage on the fan and it's ran fine every since. It stays exactly on setpoint. That being said, I have about 25 deg difference between the incoming and outgoing air at the furnace blower and i'm considering changing the jumper on the fan blower from med/high to high and see how that changes the output temperature of the air. I see that @bobboan says he's installed 100's of these units and others have experience, any feedback you have would be greatly apricated. On the thread above, it does seem like the unit runs quite a bit but in the morning has RH>60, however in the evening it has around 50%. The only thing I don't understand is, I've only seen the compressor run around 38hz, when you put it in test mode it will modulate upto about 77 but I've never seen the unit in operation above 38 even on a 100 deg day. Anyone have any input? Thanks!

  5. #44
    Join Date
    Jun 2019
    Posts
    21
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    <following> I'm having a similar problem with my 2.0 system which was installed last month. Never seems to ramp up which is fine during the day. It can hold the house steady no problem. But at night when we drop the temp a few degrees it just runs and runs. Takes SEVERAL hours to achieve a 2 degree drop. However if I put it in 'force' mode, it performs like a traditional system and easily cools the house.

  6. #45
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    9,668
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    A 38^F evap temp maxes moisture removal but reduces sensible capacity. Typicall 38^F evap is 60% sensible/40% latent. Total capacity is reduced 10%. During a part load condition colder cooling coils maintain a lower %RH.

    47^F evap provides more sensible cooling but less latent. 47^F evap is 75% latent/24%latent. With a significant cooling load of +60% cooling cycle, most homes will be <50%RH @ 75^F.

    Evenings and rainy days with low/no sensible cooling loads and +70^F outdoor dew points, will not maintain 50%RH in the home because of low/no sensible cooling loads. Supplemental dehumidification like a small whole house dehumidifier like an Ultra-Aire will maintain 50%RH even with the a/c off.

    Better but no magic. Hard to beat a simple well setup single speed a/c with a 30^F split between the return a/c temperature and cooling coil temperature. Plus an adequate sized whole house dehumidifier for the latent load during the non-sensible cooling weather, evenings and rainy days.
    Keep us posted.
    Regards Teddy Bear
    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"

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