# Thread: Low Temp R404 TXV setting

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## Low Temp R404 TXV setting

If this topic exists somewhere else, I can't find it.

How do you calculate superheat for low temp R-404a, suction pressure being 19psi, which is -16 degrees, subtracted from 19 degree suction line, close to the txv bulb. In simple math -16 subtracted from 19 would be 35 because two negatives in math make a positive causing 16 to be positive and the sum would be 35. Does it work this way in dealing with superheat when the pressure converted to temperature is a negative number and the suction line temperature is a positive number? Can someone please give me an example and clear this up for me.

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Originally Posted by cdklos
If this topic exists somewhere else, I can't find it.

How do you calculate superheat for low temp R-404a, suction pressure being 19psi, which is -16 degrees, subtracted from 19 degree suction line, close to the txv bulb. In simple math -16 subtracted from 19 would be 35 because two negatives in math make a positive causing 16 to be positive and the sum would be 35. Does it work this way in dealing with superheat when the pressure converted to temperature is a negative number and the suction line temperature is a positive number? Can someone please give me an example and clear this up for me.
Your math is correct.

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