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  1. #1
    Join Date
    Nov 2019
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    Questions, observations and possible issues with new Bosch IDS 2.0

    First let me say I'm a techie and a research junkie and have a good understanding of most tech things, but based on my early observations of my new Bosch IDS 2.0 system (5 ton unit and 4 ton air handler), I may be running into some issues.

    I've only had it for 3 days so far, but they have been 20-21 degree nights. I understand the majority of how the Bosch system works its magic without having a fully communicating thermostat and how it can "learn" from any given installation that you like a certain temperature inside and that it can calculate that based on sensors that it has for various things like head pressure, outside temperature, coil temp, electrical resistance at various points and a host of other variables. So with all of those sensors it can simulate a fully communicating thermostat except for one key piece of information.... it has no direct way of knowing what you ACTUALLY have the thermostat set to. It only knows whether heating is turned on or off. It has to guess based on learned behavior whether it has 10 degrees to go to get to your desired set point or is only a degree and half from reaching that set point.

    Based on my understanding of the above, that is the reason that some on these forums are recommending not using programmable or set back thermostats with the Bosch units. But this is my issue. I'm using a programmable thermostat not for cost savings but because my family has grown accustomed to sleeping with it very cold in the house. We have large temperature swings between night and day.

    This is how we have our set points in most cases (Piedmont region of NC):
    In summer we typically run 68 at night and 72 during the day.
    In winter we typically run 58 at night and 69 during the day.
    In winter, to keep the heat strips from running, I usually bring the temp up slowly in 4 degree increments starting at around 6AM (My smart thermostat is set to not use heat strips/aux/emergency heat unless the differential is 5 degrees or greater)

    Ok, so with all that above, I think my new Bosch has incorrectly decided that we like it around 66 degrees. From my observation it heats up well from 58 - 62 when the program changes at 5AM. From 62 - 66 the system seems to be throttling itself back and takes quite a bit of time to get to shutoff if it ever does within the 2 hours before the final temp change to from 66 to 69 degrees. Once that last program change hits the system seems to hang at 66-67 degrees like it is expecting the thermostat to shut off any minute but the shutoff never happens because it is set for 69 degrees now.

    How can I achieve both goals with my Bosch without confusing it?
    1) Cold night sleeping
    2) Ramp up slow enough that heat strips don't kick on

    This brings to light other usage scenarios that this Bosch may have trouble with. If we do get it "trained" to 68 degrees but someone in the house has a cold and we're running 70 or 72 for a few days is the system going to keep ramping back when it gets to 68 because it has learned when it gets close to those set coil temps/head pressure etc. that it is getting close to where it is normally asked to shut off? So will it just run at 10-15% of its max output at a temp of 68 degrees expecting a thermostat shut off that never comes?

    I don't think I'll run into these issues in the summer since I won't be ramping slowly between set points.

  2. #2
    Join Date
    Nov 2006
    Athens, Ohio
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    Nope. The heat pump doesn't learn anything. It receives a call for heat or cool and regulates capacity based on the suction line temperature. That is mainly affected by indoor air flow and outdoor temperature.
    OTOH, thermostats do use algorithms to determine how far in advance of the set time it needs to turn on the equipment to reach the set temperature. If your thermostat reduces the blower speed from high stage to low stage, then the heat pump will cycle down to maintain suction line temperature.
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  3. #3
    Join Date
    Aug 2002
    Southold, NY
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    How did you decide on 4-Tons?

    How many CFM’s can the existing duct handle?

  4. #4
    Join Date
    Oct 2009
    God's country - Shenandoah Valley, VA
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    You don't use setback with any type of modulating equipment; it's counter-productive to the logic of the equipment. That's not gonna change.

    It's unfortunate that you weren't made aware of this beforehand. Maybe a gradual change of life style could help.

    This is one of the downsides to higher efficiency - life style changes sometimes become necessary.
    Bob Boan

    ​You can choose to do what you want, but you cannot choose the consequences.

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