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    Vitodens 100-W temp setting question (25 Posts)

  • markt markt @ 10:34 AM
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    Vitodens 100-W temp setting question

    I have a 100-W (WB1B) and the temp setting dial doesn't make sense to me. It has a dial with positions 1 thru 6, and the manual says position 1 == 81°F and position 6 == 178°F. Presumably, it's linear, so that works out to 19.4° per increment. However, two facts don't jive with this.

    First, the manual also says the factory default, a dot on the dial at about 4.75, is 140°, but that position would be 154°.

    Second, position 3 should be 120°, but I get ~132° at position 3. To get 120°, I have to dial back to a hair less than position 2, which should be ~100°.

    Am I missing something here?

    Attached is screenshot of manual page, with a table of the interpolated dial temps drawn in by me.
    This post was edited by an admin on April 23, 2013 10:34 AM.
  • Chris Chris @ 6:27 PM
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    Do You Have

    The outdoor sensor hooked up or are you running the boiler without it? Are you piped pri/sec or have the LLH? When you run the boiler what is calling and what is the flow/gpm of what's calling? What's the return temp at the boiler?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • markt markt @ 10:36 PM
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    Outdoor reset off..

    Let me preface by noting I am not HVAC professional. I am homeowner, with just installed hydronic floor system. I am trying to better understand the system, both out of general curiosity, and practical application (not 100% sure it's all OK)

    I disconnected outdoor reset. My immediate reason for this was to force heat on, because I just had hardwood flooring installed, and flooring guy suggested I run heat before sanding and finishing, even though climate doesn't need heat at the moment (55° nights, 70° day).

    Flooring people say floor temp should not exceed 80-85°, and radiant installer said boiler temp should not exceed 120° to keep floors to under 85 (based on his experience, not theory). So I picked #3 on dial, which corresponds to 120°. I then watched and saw it go to ~135°.

    I have two zones calling. Pri/sec, not LLH. Grundfos Alpha "smart" pump. Initially, it was running in mode II, reporting 2gpm. I switched to mode III (tinkering), and it goes to 4 gpm. It makes no difference in the boiler temp however. Return temp is 90° at the moment.

    I have some questions about outdoor reset, and various other things, but I thought I'd start a separate thread on that.
  • Chris Chris @ 10:44 PM
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    Sounds To Me

    Like the Radiant installer didn't do a heat loss and the flooring guys are giving you the industry standard for floor surface temp. Both are not giving you the answer to your home and application.

    Without knowing the heat loss of the home, water temp requirement at designed based on the heat loss cannot help ya out. I can tell you that don't try to decipher the Viessmann world because it never makes sense until you can appreciate the entire thought process behind the control process.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • markt markt @ 11:39 PM
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    Installer did do heat loss

    And yes, flooring people are citing industry standard, and manufacturer's specs.

    My question was simply if anyone can explain why the boiler water temp does not correspond to what the manual says it will be at a given point on the dial.
  • Jean-David Beyer Jean-David Beyer @ 11:47 PM
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    if anyone can explain why the boiler water temp does not correspond to what the manual says it will be

    If your boiler is anything like mine, if you disconnect the outdoor reset, the boiler will go up to maximum allowed firing rate, ignoring the outdoor temperature. In other words, it will assume outdoor temperature is as cold as it can possibly get. That will make it put out water as hot as it can.
  • markt markt @ 12:02 AM
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    That's definitely not the answer

    If you look at the manual in the attachment on my first post, you can see it states:

    "With no outdoor reset installed, the dial will provide a temperature constant set-point based on the dial positon selected. Setting the dial between 1 and 6 will provide a set-point of 81° to 178° respectively."

    I verified that the dial controls the set-point. Eg, position 2 has max temp of ~120°, position 3 has a max of ~135°.

    So the dial controls max set-point, but set-point VALUES don't correspond to spec.
  • Chris Chris @ 7:56 AM
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    The Boiler

    Will still follow the curve for the setting you chose. It just rides it through modulation until it gets to set point. The boiler slowly or creeps from the bottom to the top of the curve.

    Is this a WB1B10-26 or a 35? What is the boiler pump and what speed is it set on? I would also hope he installed a mixing valve for the radiant. If not what protects the floors
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • markt markt @ 12:12 PM
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    Follow the curve?

    Note sure what you mean. Per manual, it just targets a set-point. Perhaps it follows a designed curve to reach that, but that seems beside the point. The question is why it over-shoots the set-point by 10-15°. Note this is not transient. It rises from ~75° to 120° in about 2 minutes and will run at 120 for 10 minutes. In dial position 3, same thing except it reaches peak of ~135°. To the lay engineer, it just seems like dial and burner not closely calibrated.

    This is perhaps moot, since I don't plan to run without outdoor reset. But it's curious.

    However, with reset, it also doesn't follow reset curve too closely. See attached reset curve with my overlay. The dotted line is dial 3.5, and I observed boiler peaking at 119° (for sustained periods) which corresponds to outdoor temp of ~35°. However, it was 47° at the time (I have a separate thermometer at outdoor reset sensor)

    It's a -26, Grundfos UPS15-58FC pump on middle setting.

    No mixing valve. According to installed, floor protection is to not exceed 3.5 on the dial. Gives me a little pause, given the $50K I just spent on floors...
  • Chris Chris @ 1:01 PM
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    Set Point Is

    The same curve as the ODR. The boiler just follows it. So if the coldest day of the year is 0 Degrees then you would be set on Setting #2. Have you taken an OHMs reading of the outdoor sensor to make sure it's not the cause? Page 78 of the install manual..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Paul48 Paul48 @ 4:32 PM
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    Chris

    How can it follow a curve, with no outdoor reference? I believe he is reading it this way....In the absence of an outdoor sensor, it should operate at a fixed temperature, as it states. His is not accurate to the dial setting.
  • markt markt @ 10:47 PM
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    And the curve is pointless anyway

    As you note, it cannot follow the ODR curve without the ODR sensor, but it's completely beside the point.

    It raises temp to set-point, and then settles there. The curve from cold to set-point is of no consequence whatsoever --- at least in this application, I'm not saying that's never important. I can see how the rate of rise is potentially important with a high delta T, given certain materials, stresses from thermal expansion, etc. But as I noted, it goes from 75 to 120 in under 2 mintes and stays at 120 for ~10 minutes. The exact curve in the first 2 minutes is not terribly important, and it surely has no bearing on why the peak temp does not correspond to what the manual says it would be for a given dial setting.
  • SWEI SWEI @ 11:04 PM
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    accurate analog dials

    were common up through about the mid-1970s.
  • Paul48 Paul48 @ 2:50 PM
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    Someone

    has to verify the inputs are correct. If they are, there is something wrong with how they are being used by the equipment, i.e. not properly calibrated.
  • markt markt @ 1:32 AM
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    What inputs?

    Do you mean the outdoor temp sensor? I will measure that tomorrow.

    But of course that has no bearing when in fixed set-point mode (no reset). Are you referring to any other inputs?
  • Paul48 Paul48 @ 11:01 AM
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    Dial

    The dial provides fixed inputs, and would have to be checked by a tech.
  • RobG RobG @ 12:13 PM
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    Photos

    Can you post photos of the boiler and boiler piping? It will help in ensuring piping / pumping issues are not at fault. The more photos the better.
    Rob
  • markt markt @ 1:33 AM
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    Yes

    I can post some photos tomorrow.
  • markt markt @ 11:19 PM
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    Pic

    Here's a pic. I measured outdoor sensor resistance and it's right on the curve in the manual.
  • Chris Chris @ 11:48 AM
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    What Size

    Is that near boiler piping?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • markt markt @ 12:23 AM
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    Size

    All 1", until the tees to the manifolds, which are 3/4"
  • forabunny forabunny @ 7:42 AM
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    Vitodens 100-W temp factory setting question

    Vitodens 100-W temp factory setting question...
    I have a 100-W (WB1B) and the temp setting dial doesn't do anything... I have tried to lower the temp of the boiler, and it is way too high for the house... reading between 170-180 degrees... I have it set between 2 and 3 to get it to 135... but it continues to stay at the higher temp...

    does anyone know the way to reset this dial?

    btw I don't have the outdoor sensor connected...
  • Chris Chris @ 7:46 AM
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    No Sensor

    Means no reset, means no turning down. Boiler is just riding the curve at that dial setting.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • forabunny forabunny @ 7:49 AM
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    Vitodens 100-W temp setting question

    so to reduce the boiler temp to 140° i need to do what?
  • Chris Chris @ 9:17 AM
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    Install

    The outdoor sensor and set a curve.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
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