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

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Jadnashua

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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.
 

Dana

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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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Hey, wait a minute.

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