getting closer to helping my scrolls

[ENERGY KNIGHT]

ok I will set between 15 and 20 but in the other units with superheat that high the discharge gets hot . but with the diferent piping mabey this one will be better. that will also bring down my suction right? what do you think is hapening with the oil . and what should it look like in the oil sight glass? and do you think the high side at 240 at 80 f outside is ok or will that change with higher superheat? thanks

[ENERGY KNIGHT]

I now have 85 f outside 235 psi discharge at 170 f 12 in away from comp. 225psi at filter 215 - 220psi after filter at txv. at 105 f ...suction is 60 psi at 50 f how does this look?

[Gary]

I now have 85 f outside
235 psi discharge
at 170 f 12 in away from comp.
225psi at filter
215 - 220psi after filter
at txv. at 105 f
suction is 60 psi
at 50 f
how does this look?

What does "at 170 f 12 in away from comp" mean?

What does "at 50 f " mean?

[ENERGY KNIGHT]

discharge pres. is 235 psi and the discharge pipe is 170 deg f about 12 in away from compresor outlet.
the suction pres is 60 psi and the suction pipe is 50 deg f about 12 in away from compresor.
it was 85 deg f outside. I adjusted the txv way open and took out a lot of r22 until my superheat was around 15 - 20 deg f
the oil in the sight glass on the compresor is "foamy" looking is that normal or what should it look like in there also are my pressures looking any better or close.

[aramis]

Gary its 170 degrees fahrenheit measured 12 inches away from the compressor.

235 psi is about 113 °F so your condenser is working at a 113-84 Dt = 28°C which is right at the edge between “normal” and “high” condensation.

If your maximum ambient can go 4°F higher for long periods of time then you will have condensation problems.

The same situation for suction saturation temperature is about 34°F which is at the edge of being low suction.

About the 50°F 12 inches away from the compressor: Did you insulate your sensor or thermometer when taking that measure. If not you will have to repeat it with insulation.

With a 50°F – 34°F saturation your superheat is at the edge of OK, Copeland would require 2°F higher suction temperature.

If you have small suction lines with high velocity then some level of foaming is expected anyway but it also depends on the “foam” if bubbles change size and behave violent then you should really re-check your suction temperature and pressure measurements this time with insulation at least 10 inches to either side of the sensor, including the sensor.

Measure the temperature of the air near the condenser intake and far away from the condenser if this difference is significant you may be recirculating hot air. Try to avoid this installing any air barrier at the sides and up and down of the condenser, with cardboard for example. If this improves condensation then you will have to install a definitive barrier.

If you have no problems with the air intake the system maybe still slightly overcharged.

When you compare system you have to take into account their working conditions too. Causes of high discharge are:

High condensing temperature

High superheat

Low suction pressure

... or any combination of the above. So you can’t only compare the superheat.

For example if all three above are the same but the amps drawn are different, one motor is causing more internal superheat because it is working at a higher (internal) temperature and this causes higher discharge temperatures on that system.

You may think the systems are equivalent but when you MEASURE you will discover they are NOT!

[ENERGY KNIGHT]

my compresor sit directly above my chiller barrel (evaporator) less tha 2 feet of pipe not shure what size but its very big and its factory right from climacool. this morning I started it up and my super heat was up to arround 25 deg f its 75 deg f outside now. I think I took out a little too much r22? do I have too much pres drop in my filter dryer. its a c489gt sporlan 402152 I cant find anywhere to tell me if that is the right one for 25 tons. is 10psi drop ok through filter ?and my oil looks violent once in a while when presures high and low hit the right pres at the right time ( meaning things are still fluctuating) the oil looks nice but then boom violent again I must still be missing something

[aramis]

Superheat also depends on thermal load, with higher load you should expect higher superheat.

This is something you should check with low thermal load when you get the lowest superheat it should not drop below 18°F measured at the compressor (or follow manufacturer's recomendation) and not less than 9°F at the TXV exit (unless it is an EXV).

Anyway 25°F sounds OK.

I only know the C-489-G and 10 psi is way too high it should be less than 1 psi.

[stufus]

Can you post photos of the piping arrangement from condenser to receiver something on the liquid line is a miss
Cheers
Stu

[kleen]

Hi guys dont want to hihgjack this thread but why 10 f is to low for Suction superHeat . On a Wgz unit Scroll compressers with a brazed plated evaporator water cooled or airCooled the recommand Superheat his 8 to 12 TxV or ExV .

[aramis]

Really 0.01°F should be enough but in the field you have to take precautions mainly due to measurement errors and you have to get rid of droplets travelling in the gas flow that don’t touch the tubes in straight runs.

In mechanical TXV the minimum static superheat is 7.2°F and you have to operate them a little higher.

If you read different manufacturer’s literature you’ll notice slight changes and that’s only because they use different safety factors.

[ENERGY KNIGHT]

I tink the climacool rep said 10 deg f superheat with one compresor runing and as low as 5 deg, f superheat with both compresors runing, ( two compresors share one brazed plate heat exchanger)
that might be right after heat exchanger or (chiller barrel) but the is so little pipe between barrel and compresor that it wont make mugh diference. would lowering the superheat to 8 - 10 deg f help with the high side . it looks like I have two problems the high discharge pres. and the foaming oil. again the chiller and condenser are from two different companies and something is not right. I can try and get some pictures on here. I was looking in a book on filters and the one that had 1 1/8 lines that could handle 25 tons used two filters in it and the one that had 1 1/8 line and only one filter in it could only handle like 15 tons or something like that . but I put in the numbers in the internet and didnt find tonage for my housing. I just know last time I checked It had 10 psi drop through it

[Gary]

I adjusted the txv way open and took out a lot of r22 until my superheat was around 15 - 20 deg f

The superheat is raised by closing the TXV, not opening it... and removing refrigerant is NOT the way to increase superheat on a TXV system.

Is the sight glass clear?

[Gary]

I now have 85 f outside
235 psi discharge
at 170 f 12 in away from comp.
225psi at filter
215 - 220psi after filter
at txv. at 105 f
suction is 60 psi at 50 f

235 psi = 113F - 85F = 28F TD

28F over ambient is normal.
170F discharge temperature is normal
More than a few psi drop through the filter is not normal.

[r.bartlett]

235 psi = 113F - 85F = 28F TD

28F over ambient is normal.
170F discharge temperature is normal
More than a few psi drop through the filter is not normal.

Are you trying to tease Aramis ?

[aramis]

Nah r.bartlett is just trying to stir the nest Gary.

[Gary]

Are you trying to tease Aramis ?

Nahhh... if I were trying to tease Aramis, I would point out that a temperature comparison of two flow streams is a TD, not a dT... and that a temperature change in a single flow stream is a dT.

[Magoo]

EK.
what is the TXV super heat, light load what ever load, can you indicate please.
The evaporator barrel is now a PHE, I must have missed something in earlier posts.
magoo.
ps.., cool comment Gary

[ENERGY KNIGHT]

Im sorry guys I may not have all the best info from my side , I will do my best please dont give up on me .
I do not have a reciever in the system at all right now. I dont know what the txv super heat is .I am just measuring temp on pipe about 12 inches away from comp. and the brazed plate heat exchanger is only 2 feet away . just below the compressor so the temp in the pipe can not be that much different? the sight glass is not clear right now since I have taken a lot of r22 out. Im thinking about puting just enough r22 in to get 10 deg super heat so my comp stays cool and see what my high side and oil look like . I dont know what else to do I would like to hire an engineer to come out here and tell me what I need to do but thats not up to me I hope I can get the right infp o you guys and fix it .. what do you guys need to know to make this system happy.

[MikeHolm]

What you need is Gary to come out, engineers on this side of the pond will muck it up.....LOL

[aramis]

Im sorry guys I may not have all the best info from my side , I will do my best please dont give up on me .
I do not have a reciever in the system at all right now. I dont know what the txv super heat is .I am just measuring temp on pipe about 12 inches away from comp. and the brazed plate heat exchanger is only 2 feet away . just below the compressor so the temp in the pipe can not be that much different? the sight glass is not clear right now since I have taken a lot of r22 out. Im thinking about puting just enough r22 in to get 10 deg super heat so my comp stays cool and see what my high side and oil look like . I dont know what else to do I would like to hire an engineer to come out here and tell me what I need to do but thats not up to me I hope I can get the right infp o you guys and fix it .. what do you guys need to know to make this system happy.

I learned that getting the correct information in the forum is as hard as milking a dry cow! ... and even then you can’t be sure it is correct.

Thanks to the off topic chat I didn’t notice the BPHE reference sooner!

BPHE rely on turbulent flow and enough to cover all the plates if the mass flow of your compressor(s) is not enough to satisfy both conditions the performance of the coil drops to the floor and you´ll NEVER get the capacity you want. And just for the record this applies to the water side also. This means you should respect minimum pressure drops on both sides.

You should try to get the BPHE manufacturer’s software and check what happens with smaller flow.

Without compressor and BPHE models (provided they are known here) we can’t help you with this.

Nahhh... if I were trying to tease Aramis, I would point out that a temperature comparison of two flow streams is a TD, not a dT... and that a temperature change in a single flow stream is a dT.

That’s just because here we don’t use hyperbaton that much. We pronounce it Dt. But I’ll keep it in mind thanks! (I imagine r.bartlett grinning with delight!)

Totally agree with Gary. Check and reset the TXV superheat as suggested previously. Your water split at 10 'F is fairly standard

I thought You, Gary and Energy Knight were on the same side of the pond, but maybe this is another miss pronunciation.

[Gary]

That’s just because here we don’t use hyperbaton that much. We pronounce it Dt. But I’ll keep it in mind thanks! (I imagine r.bartlett grinning with delight!)

It's not hyperbaton. TD and dT have precise meanings.

The temperature difference between the air on and the saturation temperature for any coil is the coil's temperature difference or TD.

The temperature difference between the air on and the air off for any coil is the coil's delta temperature or delta-T or dT.

[Gary]

What you need is Gary to come out, engineers on this side of the pond will muck it up.....LOL

Retired... that's ***R*E*T*I*R*E*D*** Best job I ever had...

[aramis]

It's not hyperbaton. ...

Well it is and from my point of view you use a lot of it. The correct order is adjective before noun like in Latin. This was preserved in French and Spanish, not in English.

If the meaning is clear in the context then we save a lot of explanation and we don’t have to pay attention to every little detail when we post.

For example saying “170 f 12 in away...” is clear enough in context.

Now r.bartlett must be holding his beer belly lol!

[ENERGY KNIGHT]

so any ideas on what I should do . I guess I will just add a little r22 back in until I get 8 - 10 deg f superheat at comp. then see what my presures look like. and I will keep looking to see if the filter is the correct size .
in case I didnt mention this is a(clima cool) factory built modular chiller with two 25 ton scroll compresors and one brazed
plate heat exchanger. the condenser has to be the problem because it is the only thing not factory hooked up to the chiller. and maby the piping because Im shure there other climacool modular chillers out there working.

[aramis]

Yes! Wake me up after you measure subcooling at the TXV inlet! If possible at a high and low condensing cycle.

It would be a good idea to turn off the fan control and keep the running (depending on ambient).

I would like to get compressor and BPHE model but I think this is asking too much.

Maybe you can measure the face area of the BPHE and the number of plates?

[Gary]

It needs a receiver.

[Magoo]

EK.
an example of checking TXV superheat. Not necessarily yours but,
water in 52'F water out 42'F, evaporating pressure at compressor 32'F.
System TD is water in, versus evaporating temp.
52'F - 32'F = 20'F Super heat should be in region of 60 > 70% of system TD, so 20'F x 0.65 = 13'F.
Temp at tXV thermo bulb should be 32'F + 13'F = 45'F. That is for close coupled as you have any suction strainers will change things and add pressure drop to reading taken at compressor.
Checks are done with suction gauge and contact thermometer. Opening TXV will lower the superheat closing will increase. Any adjustments wait for 15 minutes for TXV to stabalize. Idealy a schrader connection at the thermo bulb would be perfect, or on the external equalizer line of TXV.

[ENERGY KNIGHT]

I will get the subcooling at the txv and the compressor moldel number Ill try to get bphe #
also the other units have receivers and they get up to 380 psi when it gets hot . they are making cold water but we have lost 4 of the 8 compressors in 4 years. this last year we didnt loose any but I have water runing down condensers when high side gets to 300 psi. climacool says they want nothing to do with it unless we change out the condenser to the one they would have used . then they will work with us. thats fine and dandy but the new condensers are like 20g each x 8 . I think with you guys help we can get these scroll's to run

[aramis]

If they are installed close together you could have an important problem of hot air recirculation.

Supposing your condenser is correctly sized, one important difference with more expensive ones is the air throw. With good designs you can minimize hot air recirculation, cheaper models don't have these designs and you should check whether recirculation occurs.

[Gary]

We can't see it from here, but this is what I suspect is happening:

The condenser has a subcooling loop, which serves as a receiver.

The chiller has a receiver.

You can have one or the other, but not both. They are interfering with each other.

Please correct me if I'm wrong about any of this.

If the above is true, then on one of the other systems, simply bypass the receiver and you should see a big difference.

[ENERGY KNIGHT]

85 - 90 deg f entering condenser coil. 225 - 250 psi discharge . now at the txv temp is 103 - 116 deg f and 105 - 119 psi. suction was 63 psi and 52 deg f. this is all with fans full speed , and sight glass never clears.
so I added some r22 and it looks like the sight glass is clear only when I have between 8 and 9 deg f subcooling at txv. anything less and it instantly flashes off.

[ENERGY KNIGHT]

condenser.png this is my condenser before I re piped it . it is nine 1/2 in tubes four row
10 fins per inch. then there is four more 1/2 in tubes that come out of the liquid header and back to that
small header which the liquid line comes off of. I have tryed to re pipe it a bit.

[Gary]

It would be clearer for me if you could report temps/pressures in this format:


Evap air in temp:
Evap air out temp:
Low side pressure:
Suction line temp at TXV bulb:

Cond air in temp:
Cond air out temp:
High side pressure:
Liquid line temp at TXV:

[ENERGY KNIGHT]

bphe in temp: 54 deg f
bphe out temp: 44 deg f
low side pressure: 63 psi
suction line temp : 52 deg f


cond air in temp: 85 - 90 deg f
cond air out temp: not shure
high side pressure: 225 - 250 psi
liquid line temp at txv: 103 - 116 deg f
liquid line pressure at txv: 205 - 219 psi

[Gary]

bphe in temp: 54 deg f
bphe out temp: 44 deg f
low side pressure: 63 psi
suction line temp : 52 deg f


cond air in temp: 85 - 90 deg f
cond air out temp: not shure
high side pressure: 225 - 250 psi
liquid line temp at txv: 103 - 116 deg f
liquid line pressure at txv: 205 - 219 psi

54 - 44 = 10F evap dT. That's good.
63 psi = 36F SST. 52 - 36 = 16F SH. That's good.

Averaging:

87.5 - ? = ? cond dT
237.5 psi = 114F SCT. 114 - 110 = 4F average SC. Too low. Your subcooling needs to be 10-15F... or a clear sight glass, whichever comes first.
114 - 87.5 = 26.5 TD. That's good.

You need to add more refrigerant to bring the subcooling up to 10-15F... and you need a receiver OR a subcooling circuit.

The liquid pressure at the TXV is going to be severely affected by modulations in the valve, which makes this reading useless.

Ideal would be pressure and temperature readings at the sight glass.

[Magoo]

EK.
your initial post indicated a vertical air cooled condenser, "x " wide and " ÿ "inches high, the pic/sketch of your of condenser with full face sub cooling will complicate things I beleive, with additional internal pressure drop/ loses in condenser.Generating a high pressure differential across condenser. Generally a sub cooling circuit is at the bottom on a vertical arrangement air cooled condenser.
magoo

[ENERGY KNIGHT]

not shure what you mean . the coil is 50 in tall and 70 in wide . the air flows horizontal through the coil. and the subcooler is at the bopttom.
I was trying to measure the air temp going into my coil I noticed the temp was a lot higher than outside
air. I think the air blowing out the top is coming back down and through again . is that heard of ?

[Magoo]

OK.
the condenser coil is mounted vertically, and air flow is horizontal. Hot off coil air re-generation is a constant problem with induced air patons as most of air flow is off the fan blade tips so goes side ways and can be re-introduced back into air on air flow. Baffling may be necessary to direct air away from re-generation.
Seems that all your problems relate to location and positioning of remote air cooled condenser and receiver vessel.

[ENERGY KNIGHT]

with a clear sight glass my discharge temp - outside air is 30 deg f
what should I set my super heat at when measuring 6 in from comp. 8 - 12 or 15 - 20 deg f ?
what should suction pres be with 54 deg f water in and 44 deg f out of bphe ?

[Gary]

what should I set my super heat at when measuring 6 in from comp. 8 - 12 or 15 - 20 deg f ?

At 10F superheat, all of the liquid droplets have boiled off. Some compressor manufacturers call for a minimum of 15F SH at the compressor inlet, while others call for 20F SH at the compressor inlet.

It's a trade-off. We want to completely utilize the coil, without flooding the compressor.

[mad fridgie]

not shure what you mean . the coil is 50 in tall and 70 in wide . the air flows horizontal through the coil. and the subcooler is at the bopttom.
I was trying to measure the air temp going into my coil I noticed the temp was a lot higher than outside
air. I think the air blowing out the top is coming back down and through again . is that heard of ?

Now this making a lot of sense.
Yes air re-circ is a common problem.
Stop this first, before you make your next move!

[ENERGY KNIGHT]

ok I now have the condenser re-piped and the receiver out next to the condenser
I also have a baffle built to keep the hot air from coming arround
I have a clear sight glass
10 deg superheat
30 deg difference between discharge and ambient
new larger contactor and timer
should I install an oil seperator on discharge line so oil does not go through system?
I believe that would help my foamy oil let me know what you guys think on this thanks.

[Gary]

Evap air in temp:
Evap air out temp:
Low side pressure:
Suction line temp at TXV bulb:

Cond air in temp:
Cond air out temp:
High side pressure:
Liquid line temp:

[ENERGY KNIGHT]

sorry Gary its really cool here 55 deg f . it was hot. in need te get those readings with fans full speed .
what would you say min. high side pres. should be ? its suposed to be mid 60's f tommarow could I run fans full speed and get you those readings?

[ENERGY KNIGHT]

would an oil seperator be helpfull

[Gary]

I've seen no indication of oil problems.

[ENERGY KNIGHT]

I would like to post the new readings but I'm not shure about my superheat where should I be most concerned about the temp of the pipe. my compressor is very cold and most of the comperssor is very wet. I have about 10 deg f superheat at compressor inlet. some say at comp i should have at least 15 deg. f . but there is only about 3 foot of insulated pipe between bphe and compressor so the temp is the same . what do you think I should do?

[ENERGY KNIGHT]

o and when I change the filter just before the txv I get about a coffee cup of oil out of filter housing.

[Gary]

The compressor inlet superheat needs to be at least 15-20F... and the compressor crankcase should be warm. The cold crankcase indicates flooding, which washes oil out of the compressor. Adjust the TXV superheat.

[ENERGY KNIGHT]

ok Gary I will adjust the txv in a little thanks a lot for helping me. after I get around 15F I will try and get all those other readings and post them .