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Thread: Why does a 1" zone valve have a tiny 3/8 port?

  1. #16
    DIY Member Belmondo's Avatar
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    I do have the boiler set at 180. I'm not sure I would want to raise it, as my radiant is a suspended pex system simply running as a straight zone, no low temp exchanger at all. The boiler seems to be doing OK getting the tank up to 150, but if I can speed the recovery I can drop that down. At this point installing the 1", 33 Cv W-R valve seems low hanging fruit at $123 and a quick easy install, vs the rebuild of both sides of the zone manifold I was contemplating.

    I don't think my walls are that cold, I have an IR thermometer, and my readings on my windows were in the high 50's when it was pretty cold out. I was interested in whether the large coated and gas filled window in my kitchen was any more insulating than the rest which are standard 2 pane. It wasn't, maybe they're more effective at keeping out the sun than the cold. I've never felt the walls were as cold as the windows, there are no drafts. Maybe this winter I'll keep an eye on it, and get temp reading from both the plaster and brick walls.

  2. #17
    Retired Defense Industry Engineer jadnashua's Avatar
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    An IR thermometer is only accurate comparing similar materials, and UNLESS it has an adjustable reflectivity feature to calibrate it for different materials can provide very inaccurate readings.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #18
    DIY Member Belmondo's Avatar
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    I'm not shocked that my $10 Harbor Freight thermometer has drawbacks, but it seems accurate every time I've checked it. I got it when I installed the radiant, I had a digital thermometer with a probe on the floor in one spot, but used the IR to check the eveness of the heat. It read the same as the probe on the floor. Are the laser units more accurate? (not that I can rationalize buying one, much as I loves my toys!)

  4. #19
    Retired Defense Industry Engineer jadnashua's Avatar
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    A direct contact device is not what I thought you said you were talking about! An inexpensive laser IR thermometer won't likely have any adjustments to it, and may be factory calibrated to one type of surface (say a painted wall), and while it could be quite accurate at that type of surface, it could be way off when trying to compare say a painted surface with glass. Here's a link that shows the range http://www.scigiene.com/pdfs/428_Inf...ytablesrev.pdf. You'll get skewed results unless you can adjust the unit to what it's looking at. It's not always easy to get a good, reliable contact reading as sometimes, just touching the surface with the probe can skew the results, or insulating it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #20
    DIY Member Belmondo's Avatar
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    I wasn't originally talking about the direct contact probe, I brought that up just to say it confirmed the cheapie IR unit, at least reading a floor. Even the probe unit was a Depot cheapie, but I thought it was great for tuning heating systems as it logs hi and lo temps. If I was pro, no doubt I'd get the real laser deal.

  6. #21
    Retired Defense Industry Engineer jadnashua's Avatar
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    My point, though, is that without changing the emissivity of the non-contact device, it is only good for the thing it was calibrated for. It is still good for comparative readings of same materials, but those values could be quite different from reality. Now, there are a lot of things that are close, but they will be different.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #22
    In the trades Dana's Avatar
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    ANY IR thermometer requires that the emissivity of the different surfaces be identical when taking a comparative reading. Windows (particularly those with hard-coat E on the exposed surfaces) will be WAY off. Bare copper heating piping will show a much lower temperature than the iron-bodied pump that it's directly connected to due to it's much lower emissivity. No IR thermometer can be considered a precision instrument, but will give pretty good results over a wide temperature range provided it's a high-emissivity surface.

    Putting hockey-tape on the surface to be measured is a common way to put a high-emissivity measurement point on any surface where you don't want to permanently alter the surface. Spots of flat-black spray paint works for the "don't care" situation.

    With a indirect setpoint of 150F and a high-limit of 180F you will be almost guaranteed to have burner cycling on calls from the indirect, even with a 6-7gpm flow and a ~20F delta-T on the boiler loop, since the return water from the HX in the tank has to be many degrees above the tank temp to achieve a heat exchange rate comparable to the boiler's output. Drop the setpoint to 140F or even 130F and see if it still cycles.

    PEX will actually tolerate 200F water at typical heating system pressures, even though manufacturer's spec it for 180F at higher pressures (though it's better to be conservative about it. (IIRC Wirsbo has an experimental system for their PEX that has been running at or above 200F for at least a couple of decades now, with no signs of degradation.) Pushing the high-limit to 190F will be fine, but I wouldn't take it to 220F without a thermostatic mixing valve to control the temp on any PEX loops.

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