subcooling

how do you measure subcooling

you convert the head pressure reading to tempreture then messure the liquid line tempreture the dif between the saturated tempreture and actual temp is subcooling

read Refrigeration 101: by Gary

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Originally Posted by martinw58

you convert the head pressure reading to tempreture then messure the liquid line tempreture the dif between the saturated tempreture and actual temp is subcooling

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This not quite correct, actual sub-cooling you need to measure the liquid pressure (and convert to a saturated temperature) and measure the actual liquid temperature, the difference between the temps is the actual level of sub cooling. Sorry for being so perdantick, as this is one of my pet subjects.:D

Yes oldtimer
madfridgie is very correct as usual. A few more tips - If no access point is available at outlet of cond or liquid line allow for pressuredrop through condenser of more than about 5psi. There is nothing like an accurate measurement so get your self a superheat calculation kit like yellow jacket (ritchie) and measure the refrigerant temp and pressure directly. Even if you have to pump down the unit and weld in a schrouder port anywhere on the liquid line.

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Originally Posted by Tesla

Yes oldtimer
madfridgie is very correct as usual. A few more tips - If no access point is available at outlet of cond or liquid line allow for pressuredrop through condenser of more than about 5psi. There is nothing like an accurate measurement so get your self a superheat calculation kit like yellow jacket (ritchie) and measure the refrigerant temp and pressure directly. Even if you have to pump down the unit and weld in a schrouder port anywhere on the liquid line.

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hes asking about subcooling not superheat :D

Cool tony--1
But just check it out first - the superheat calc kit measures sub cooling directly as well as superheat.

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Originally Posted by Tesla

Cool tony--1
But just check it out first - the superheat calc kit measures sub cooling directly as well as superheat.

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That we call humor, my friend.;)

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Originally Posted by mad fridgie

This not quite correct, actual sub-cooling you need to measure the liquid pressure (and convert to a saturated temperature) and measure the actual liquid temperature, the difference between the temps is the actual level of sub cooling. Sorry for being so perdantick, as this is one of my pet subjects.:D

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sir how can i know if the subcooling measure are correct compare to the superheat of evaporator

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Originally Posted by tony--1

hes asking about subcooling not superheat :D

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sorry sir im just new im quite thinking the balances of both measurement ,like in multi stage.

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Originally Posted by karas

sir how can i know if the subcooling measure are correct compare to the superheat of evaporator

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Kamusta (tagalog not to good)
Sub cooling has no direct relationship to evaporator superheat. If you have no sub cooling at the expansion valve, then you are likely to have a mix of liquid and vapour. The mix will will reduce the mass flow through the valve, causing the evaporator to be starved (not enough liquid) if the evap is starved then you will have high superheat.
I hope this is what you meant?

The others have measuring subcooling correct, but system needs to be fully loaded, all cond. fans running. May have to manipulate low ambient controls if cold enough outside.