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Head pressure
johnjohn89
Member Posts: 114
I work on r410a system(txv) today! My head pressure run 425 psig with 0 subcooling and my low side ( back pressure) only run 105 psig my suction line 72f ( I got 38 superheat)
I test txv sensing bulb into hot water it did react, I put temperature pro cross filter drier inlet and outlet no pressure drop, I couldn’t figure out today
anyone got any opinion? Thanks
I test txv sensing bulb into hot water it did react, I put temperature pro cross filter drier inlet and outlet no pressure drop, I couldn’t figure out today
anyone got any opinion? Thanks
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Comments
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Sounds undercharged but i'm not the expert on this.0
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72 suction line? How’s your airflow?
There was an error rendering this rich post.
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Do you have ice on like the bottom 1/4 of the evaporator?0
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johnjohn89 said:I work on r410a system(txv) today! My head pressure run 425 psig with 0 subcooling and my low side ( back pressure) only run 105 psig my suction line 72f ( I got 38 superheat)
I test txv sensing bulb into hot water it did react, I put temperature pro cross filter drier inlet and outlet no pressure drop, I couldn’t figure out today
anyone got any opinion? Thanks0 -
Zero subcooling means there's no liquid refrigerant packed up in the condenser. High head pressure means there's either an obstruction downhill from the condenser or no heat leaving the condenser. High superheat means the TXV can't feed enough liquid to bring the superheat down, which goes along with no liquid making it to the valve. Assuming indoor & outdoor conditions aren't crazy, dirty condenser coil. What's the approach temp?0
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dirty condenser, Add a little charge and see what the superheat does. Could be a bad txv. Non condensable in the system0
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ratio said:Zero subcooling means there's no liquid refrigerant packed up in the condenser. High head pressure means there's either an obstruction downhill from the condenser or no heat leaving the condenser. High superheat means the TXV can't feed enough liquid to bring the superheat down, which goes along with no liquid making it to the valve. Assuming indoor & outdoor conditions aren't crazy, dirty condenser coil. What's the approach temp?0
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Approach temp is the difference between the liquid line temperature & the outdoor air temperature. In other words, if your liquid line temp was 100° & the outdoor air temp was 90°, your approach would be 10°. IIRC New Lennox charge by approach & not subcooling.
In any case, I'm being you have high approach.
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ratio said:Approach temp is the difference between the liquid line temperature & the outdoor air temperature. In other words, if your liquid line temp was 100° & the outdoor air temp was 90°, your approach would be 10°. IIRC New Lennox charge by approach & not subcooling.
In any case, I'm being you have high approach.
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@all thank u for the helping0
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ratio said:Approach temp is the difference between the liquid line temperature & the outdoor air temperature. In other words, if your liquid line temp was 100° & the outdoor air temp was 90°, your approach would be 10°. IIRC New Lennox charge by approach & not subcooling.
In any case, I'm being you have high approach.
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pecmsg said:
I’m used to “Approach” being used on Water cooled units. Lennox now wants that information?
That's what my li'l buddy said, charge to an approach of whatever. A couple of caveats: these are commercial condensers (10-15 ton) & that's what he told me, I haven't actually verified it myself.
As long as the outdoor coil's clean, it should work.
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