High Suction Press.

[vernilla]

Im sure this is supposed to go in the pro forum but I dont have quite enough post yet. Hopefully after this thread I will be able to apply.

Im working on a Goodman Packaged roof top. I think I know the problem but would like to hear some input from some of you guys.

Return temp 80
Supply temp 70
Suction Press 92
Discharge Press 260
Superheat 22
Subcool 6

The unit has two systems. Each one 5 tons. Each one running the same readings (with in +/- 2 degrees on superheat and sub) I adjusted txv to bringdown superheat but as I did that the suction press went up and the delta across the coil dropped (got down to about 4 degrees delta with a superheat of 10)

Anythoughts are greatlly appreciated!

[pageyjim]

Amp draw?, OAT? Cond. coil clean? Pressures on both circuits?Wetbulb? Filters clean? Can't have too much info.Always a good habit to have too much info when you need help.

[vernilla]

Amp draw?, OAT? Cond. coil clean? Pressures on both circuits?Wetbulb? Filters clean? Can't have too much info.Always a good habit to have too much info when you need help.

Amp draw comp1 L1=17 L2=16.5 L3=16
comp2 L1=19 L2=17 L3=17
OAT DB=95
WB=80
Cond coil clean? yes
Press on both circuits
Suction1=92 discharge1=260
Suction2=93 discharge2=270
Wet Bulb Return=68
Supply=64
Filters Clean? yes
Can't have too much info. SORRY!
Always a good habit to have too much info when you need help. Thanks for the advice!

[ascj]

Im sure this is supposed to go in the pro forum but I dont have quite enough post yet. Hopefully after this thread I will be able to apply.

Im working on a Goodman Packaged roof top. I think I know the problem but would like to hear some input from some of you guys.

Return temp 80
Supply temp 70
Suction Press 92
Discharge Press 260
Superheat 22
Subcool 6

The unit has two systems. Each one 5 tons. Each one running the same readings (with in +/- 2 degrees on superheat and sub) I adjusted txv to bringdown superheat but as I did that the suction press went up and the delta across the coil dropped (got down to about 4 degrees delta with a superheat of 10)

Anythoughts are greatlly appreciated!

So you have 22 degrees SH on a 92psi suction line. So you line temp is about 85 degrees. So your suction line is hotter than your return air? Is this a HP? You have HGP?

[pageyjim]

Amp draw comp1 L1=17 L2=16.5 L3=16
comp2 L1=19 L2=17 L3=17
OAT DB=95
WB=80
Cond coil clean? yes
Press on both circuits
Suction1=92 discharge1=260
Suction2=93 discharge2=270
Wet Bulb Return=68
Supply=64
Filters Clean? yes
Can't have too much info. SORRY!
Always a good habit to have too much info when you need help. Thanks for the advice!

No need to be sorry but always good advice esp. if its your boss or tech support.
Amp draw is given but you didn't show RLA which is on nomenclenture plate. But that is probably not the problem since both are close.
Are you drawing in an excess of outdoor air? Economizers stuck open? You may think the condenser coil is clean but it mat not be.
Check TXV feeler bulb is insulated and mounted right.
When you take your measurements are you opening a panel that effects the airflow over the condenser?

[Chiller Guy]

I'm in Delaware and know what kind of weather we are having here and probably there! We are at or above design conditions a lot this year. Whats chances that you have more load than you have machine? Do things fall into line after cooling down at night ? You have two circuits exibiting the same problems. Look for the common denominator (ambient maybe)? Water on condensers?

[cperk]

Sounds to me also, that you have too much load on your evap. Prob why subcooling is low, because your TEV is wide open trying to get superheat down. I know this sounds crazy, but I would try to add some gas and get subcooling right, then superheat might drop and in turn TEV is going to pinch off to lower suction press. and saturation temp.

[vernilla]

No need to be sorry but always good advice esp. if its your boss or tech support.
Amp draw is given but you didn't show RLA which is on nomenclenture plate. But that is probably not the problem since both are close.
Are you drawing in an excess of outdoor air? Economizers stuck open? You may think the condenser coil is clean but it mat not be.
Check TXV feeler bulb is insulated and mounted right.
When you take your measurements are you opening a panel that effects the airflow over the condenser?

No economizer on this unit.

Txv bulb is insulated but not to my standards. It is foam taped but could be effected by the air stream. I dont think it would be the cause of the problem being that it ran that way in the past.

The panel that is removed for readings doesnt effect the condenser flow.

[vernilla]

I'm in Delaware and know what kind of weather we are having here and probably there! We are at or above design conditions a lot this year. Whats chances that you have more load than you have machine? Do things fall into line after cooling down at night ? You have two circuits exibiting the same problems. Look for the common denominator (ambient maybe)? Water on condensers?

Thought about that but I think it should still have more than a 10 degree delta?

[vernilla]

Sounds to me also, that you have too much load on your evap. Prob why subcooling is low, because your TEV is wide open trying to get superheat down. I know this sounds crazy, but I would try to add some gas and get subcooling right, then superheat might drop and in turn TEV is going to pinch off to lower suction press. and saturation temp.

I think that is my next move. Just kinda has me confused with the high suction. That goes againt everything that I've been taught.

Low suction=low charge and visa versa??

[pringlel]

So you have 22 degrees SH on a 92psi suction line. So you line temp is about 85 degrees. So your suction line is hotter than your return air? Is this a HP? You have HGP?

I would be tempted to pull enough refrigerant out to cause your liquid line to be at saturation then i would take a liquid line temp to compare it to your saturation temp. If there not close recover refrig and start over with virgin refrig.
As stated something doesnt sound right with your suction pressure and suction SH. SH is about spot on copeland would like A Min of 20 at the compressor. If you are taking this at the comp that shows your TXV is doing its job, and you have adequate sub cooling maybe not design.
As stated I would be looking hard for a hot gas bypass

[cperk]

Sounds to me also, that you have too much load on your evap. Prob why subcooling is low, because your TEV is wide open trying to get superheat down. I know this sounds crazy, but I would try to add some gas and get subcooling right, then superheat might drop and in turn TEV is going to pinch off to lower suction press. and saturation temp.

Are the comps. on totally diff. circuits? Or are the comps.on same circuit?

[vernilla]

Are the comps. on totally diff. circuits? Or are the comps.on same circuit?

Different circuits.