low high-side pressure, help

[mackking]

there is no other high side tap

[mackking]

there is no other tap in the high side

[Gary]

Ok... then we have no choice but to trust the high side pressure measurement at the shutoff tap.

[Gary]

ok the stat says 76 room temp
evap-air in 76
air out 65
condensor- air in 79
air out 88
suction line temp 72
liquid line 89
low side pressure= 66 psi
high side pressure=170 psi

suction line temp is 72F
saturated suction temp for R22 @ 66 psi is 38F

72 - 38 = 34F superheat

Add refrigerant slowly until the superheat is about 15F, then take a new full set of temp and pressure readings.

[tonyelian]

hi
is the unit is enough for the area coverd more detail pls
size of both orifices &u fitted with o ring&right direction
did condensing unit match air handling
more detail pls

[mackking]

suction line= 56f
liquid line=93f
low side=85psi
high side=200psi
condensor air in=82f
condensor air out=94
evap air in=77f
evap air out=59f

[mackking]

its a 3 ton goodman heat pump with matching air handler (both brand new).
its in a 900sq ft mobile home (with a lot if insulation).
the indoor orfice is a .82 and the outdoor orfice is a .55
both are in correctly and workin correctly

[Gary]

The .082 orifice is too large and is overloading the system. You need to switch to the .078 and then take a new set of readings.

[mackking]

i know the orfice is too large but when i put the .78 in, the vent temp rose 8f

[Gary]

We need to get everything in balance. And at this point the orifice is too large.

[mackking]

ok ill put it back in but how will i get the temp down
how cold can i make it get?

[mackking]

am i expecting too much from this unit? because i really expected to see temps in the 40's.

[mackking]

it would seem that my understanding of how the system works is wrong, so what directly determinds how cold the coil gets?

[Gary]

Planning on turning your mobile home into a refrigerator?

[Gary]

Once we get the system in balance the next step will be to reduce the blower speed.

[mackking]

well kinda, i just want it to cycle during the day instead of running all the time. i keep the stat set on 70f, during the day it get up to about 82 of 83. when night falls, it takes it until 2am to bring it back down to 70.
i would have said that it was an insulation problem, but i rebuilt the house last year and completely packed every wall with styrofoam and fiberglass insulation then sealed the outside with thermoply before putting the siding back on. also if it were an insulation problem, i would figure it would recover fast at night or during the rain but it dont. and im trying to reduce my light bill from $400.

[Gary]

well kinda, i just want it to cycle during the day instead of running all the time. i keep the stat set on 70f, during the day it get up to about 82 of 83. when night falls, it takes it until 2am to bring it back down to 70.
i would have said that it was an insulation problem, but i rebuilt the house last year and completely packed every wall with styrofoam and fiberglass insulation then sealed the outside with thermoply before putting the siding back on. also if it were an insulation problem, i would figure it would recover fast at night or during the rain but it dont. and im trying to reduce my light bill from $400.

I have 3 tons for 1500 sq ft and it pulls down pretty fast. For 900 sq ft it should pull down very fast... but first we need to get it working right.

[mackking]

i couldnt agree more. ive never had this much trouble. ive always just charged a system to 72psi on the low side and it worked but like i said i havent done a whole lot of it.

[Gary]

i couldnt agree more. ive never had this much trouble. ive always just charged a system to 72psi on the low side and it worked but like i said i havent done a whole lot of it.

I've heard of a lot of different ways to charge a system, but that is probably the worst.

[Gary]

BTW, right now you have 6F superheat, which means the system is overcharged. I clearly remember saying charge it to 15F superheat.

[mackking]

well maybe before this is all said and done, ill know the correct way. its sure been a learning experiance.

[Gary]

You might want to read through this thread:

http://www.refrigeration-engineer.co...ad.php?t=19701

[tonyelian]

hi
ur orifice size should be 065 indoor&o70 outside

[mackking]

ok i put the .78 back in and reset it and set the evap blower to low(from medium)
suction line=62f
liquid line=88f
lowside=80psi
highside=190psi
condensor in=79f
condensor out=89f
evap in=76f
evap out=60f

[mackking]

the .78 came with the air handler and the .58 was factory installed in the condensor. from all the experiments ive tried, when i install a smaller orifice, the vent temp rises. my only explination is that when i install a smaller orifice, it restricts the refrigerant flow too much and cant keep up with the coil. but i could be wrong.

[Gary]

With suction pressure that high the discharge pressure should be much higher. I'm thinking you may have an inefficient compressor.

Close the suction line shutoff valve and see if the compressor will pump down into a vacuum.

[mackking]

what would cause the compressor to be inefficient? and what would cause two of them to be? like i said before, this is the second system and both of them act the exact same way. i have examined both refrigerant lines inside and out and both are fine and restriction free.

[mackking]

um not very well. it pulled it to a 8inhg vacuum. is that enough? or could it be the reversing valve leaking? i have questioned the reversing valve all along but i dont know how to check it.
it doesnt seem to have much efficientcy in heat mode either but that could be a compressor too, right?

[Gary]

I found a piston kit chart. Let's see if we can find the official right size:

http://site.famousparts.com/goodman/PDF/PKC-00U.pdf

[mackking]

the condensor is a model # gsh130361bb
the air handler is a model#
adpf304216ba
i couldnt find the exact app for this unit in the charts.

[mackking]

oh i dont know if it matters, but whan i closed the suction shut-off valve, the high side pressure DID NOT rise.

[Gary]

Is there a model# on the coil?

[Gary]

oh i dont know if it matters, but whan i closed the suction shut-off valve, the high side pressure DID NOT rise.

Did the low side pressure at the compressor inlet go into a vacuum?

[mackking]

which coil? but probly not there is not alot of id numbers on it

[mackking]

not much of a vacuum, 8 inhg

[Gary]

which coil? but probly not there is not alot of id numbers on it

The indoor coil.

[Gary]

the condensor is a model # gsh130361bb
the air handler is a model#
adpf304216ba
i couldnt find the exact app for this unit in the charts.

The ADPF304216BA can have a 2.5 to 3.5 ton coil.

As near as I can tell a 2.5 ton needs .065 and a 3.5 ton needs .078

[mackking]

i cant find any other numbers, so what do u think about the vacuum and pressure?

[mackking]

i was told that the air handler was built to range from a 2 1/2 ton -3 1/2 ton, making it a good candiate for my 3 ton condensor

[Gary]

I am not ready to blame the compressor just yet. We need to get the right orifice in there and see what the temps/pressures tell us.

The .078 is just too large, so we can assume that the coil is not 3 1/2 ton.

Unless you can find the btu rating for the coil we will just have to keep changing orifices.

I want to see that suction pressure down around 70 psi (or a little less) with about 15F coil outlet superheat.

[mackking]

well before i knew about the superheat method, i was setting the suction pressure at 70psi or little below, and when i put in smaller orifices(trying to raise the head pressure) i would loose a significant amont of efientcy. wich is how i ended up with the .82 orfice, the gave me the coldest vent temp.
it still really concerns me, that when i shut off the suction valve completly, the high side didnt change but the low side came down to a small vacuum. before i blamed the compressor, i would question the reversing valve, but i dont know how to check it.

[Gary]

You keerp mentioning the vent temp as if it were important.

[mackking]

if it dont blow cold then whats the point?

[mackking]

60f just isnt cold

[Gary]

if it dont blow cold then whats the point?

The point is transferring heat.

[mackking]

call it whatever you like but the whole fact of the matter is that it cant transfer heat if it cant make heat, and with a head pressure of 180psi, it cant make heat. and when i close off the suction line and it still dont raise the head pressure, nothing will no matter how many orifices i throw at it.

[Gary]

call it whatever you like but the whole fact of the matter is that it cant transfer heat if it cant make heat, and with a head pressure of 180psi, it cant make heat. and when i close off the suction line and it still dont raise the head pressure, nothing will no matter how many orifices i throw at it.

Why would you expect the head pressure to rise when you shut off the suction valve?

[Gary]

Did you try another orifice today?

[mackking]

no i didnt have a chance, but i would expect the pressure to rise since the refrigerant has nowhere to go, it would be compressed in the coil, hense the pressure should skyrocket.

[mackking]

the only other orifice i have is a .73, but when i installed it before it acted like it had too much restriction to flood the coil with enough refrigerant to keep it cool.