Carrier A/C, Again!

[hrdwrkingacguy]

Re: Carrier A/C, Again!

everything i am about to tell you is based on the assumption your system is R-22...You are looking at the chart for the wrong refrigerant or reading it wrong...157# on 410a would be right if you indoor air temp was 90 degrees...85# on r-22 is to high...If you have a thermometer you can read the liquid line temperature it should be about 12 - 15 degrees higher then the outside air temperature entering the outdoor coil...

Basically from the beginning your data plate refrigerant charge is based on a line set that 25'(long radius 90's add 3' of total length to the lineset). to get the charge really close add the 90's + length over 25' and its .3 oz per ft you need to add...

or you could charge to 9 degrees subcooling and be done...

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

For a r-22 system your not too far off. Let the system bring the indoor temp down to 75 and check again to see if it falls to around 65 psi. A 22 degree drop across the coil is pretty good but fan speed also factors into the equation so your looking at ballpark. Put a amp-clamp on the compressor and check it against the nameplate FLA.

Not trying to start a war but this advice is totally wrong....That system will be flooding back like crazy at 65#...FLA of the compressor is based on ARI test environment with a 78 degree indoor temp/90 degree outdoor temp with a 56 degree wet bulb...FLA is going to change based on load and we already know your compressor pumps...The only way to charge a txv system is by measuring subcooling...condenser saturation temperature in the liquid line - liquid temperature < 9 you need to add > 9 you need to remove...

 

[bigdee]

Re: Carrier A/C, Again!

Not trying to start a war but this advice is totally wrong....That system will be flooding back like crazy at 65#...FLA of the compressor is base on ARI test environment with a 78 degree indoor temp/90 degree outdoor temp with a 56 degree wet bulb...FLA is going to change based on load and we already know your compressor pumps...The only way to charge a txv system is by measuring subcooling...condenser saturation temperature in the liquid line - liquid temperature < 9 you need to add > 9 you need to remove...

I apologise if I was mis-leading.....I know FLA cannot be used accurately judge a judge but it can alert you to being overcharged which I believe to be the case here. I agree 85 at his temps is HIGH for 22 but there is no need to panic.....his house has been without AC and soaking up alot of heat (I live in the same area) so give it time to stabilize the indoor temp to normal and check again. Those refrigerant charts can be misleading because of errors when it comes to measuring indoor/outdoor temps. My 40 year old Lennox was recharged by weight last summer, @90 degrees indoors I was getting close to the same suction pressure (80psi) After 2 days I checked again and it was at 65psi.

 

[Nandy]

Re: Carrier A/C, Again!

Got you guys some numbers:
73 - Air incoming to the evap right between the return fan and the evap coil.
50 - Air leaving the evap into the plenum.
71 - Temperature across the house (ac thermostat shows 69 but that is irrelevant I think)
89 - Outside temp.
104 - Temp of the air coming from the condenser fan.
68 - Suction Line temp at outside unit next to recharge port.
92 - Liquid line temp.
66 to 70 PSI - Suction line pressure. It does change, seems like when the compressor is off/on. Stays mostly at 70.
255 to 275 PSI - Liquid line pressure. It does also change, not exactly at the same time the suction line. Stays mostly on 275.
3.5 amp - Compressor amperage.
Dee, I could not find the FLA number you mention. I have RLA and LRA in the label. The label is on post #30 http://forums.iboats.com/showthread.php?t=392715&p=3257879&viewfull=1#post3257879

I used the chart in the unit to calculate my pressure. and it came out at 67 psi so at worst case scenario im 3 psi over. Not sure that will cause any problems.
It is so great to have all the house cooling now, before we were all spending most of the time that we could in the living room where the window unit is. That is the only part I will miss. Last night when the ac starting cooling and the house got comfortable it was like someone drop a bomb and everyone went to their room. I think im going to fake a/c failures in the future to keep everyone in the same room. Other than dinner it is the only other time it happens....

I still have a few things to do. The overflow dripping pan had to be moved to cover the larger coil and be able to fit it under the A frame so the pvc pipe will have to be cut. The main drip pvc pipe did not had to be cut or added, just moved a bit to the side. I had to build a cover to seal the unit where the coil was taller than the plenum and the furnance and the section on the plenum is sweating big time so I have to reopen the coil case and add some of the insulation I forgot to do. Other than that, and if y'all agree with the pressure being fine, Im done with this baby!

 

[bigdee]

Re: Carrier A/C, Again!

congrats for a job well done. Now sit back and reward yourself with a cool drink. RLA=running load amps FLA=full load amps......if you are at or under RLA you should be fine.

 

[Nandy]

Re: Carrier A/C, Again!

Thanks to all of you for all the help. Of course the filter got home friday evening... Aint that something!!!

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

This unit isn't right at all...you are on the way to a dead compressor...See how the liquid line temp / outdoor ambient is like 3 degrees different...This unit has a seriously underfeeding txv, or possibly a liquid restriction...

Charging chart is irrelevant with the system you now have...That chart only applies to a matched system...

275# = 125 degrees - 98 degree liquid temp is 27 degrees subcooling = overcharged/restriction
68 degree suction line - 70# = 40 degrees = 28 degree superheat = not enough refrigerant flow/starved evaporator...

If you are flowing the liquid in the system the condenser is stacked up with and the evaporator is underfeeding...If you followed some of the earlier posts I talked about physical coil size and the fact that you have a large indoor coil in relation to you outdoor unit....Outdoor coil should be about 1.5x the size of indoor(You don't have that relationship anymore) you are more or less 1 to 1...

Basically your flow rate from your condenser isn't enough to satisfy the demand of the indoor coil...You need to adjust in the stem on the txv if there is one to lower the superheat....at 70# your suction line should be 52ish and your in your case your discharge pressure should be 245 and your liquid line should be about 110...

Above 60 degree suction line temp your going to cook the oil in your compressor and its going to die...forget FLA you need a low 50's suction line and a liquid line 15 degrees warmer then the out door temp with about 10 degrees of subcooling...

I think your TXV isn't adjustable...You can get a 3 ton aftermarket txv with a equalizer line for about 75$ from ARS or RSD...I think you are going to need to open up the txv to feed enough refrigerant through the system...If you need a TXV and have either of those parts houses near by(American refrigeration supplies, or Refrigeration supplies distribution) I can will call it and you can go in and pay cash for it...

 

[dolluper]

Re: Carrier A/C, Again!

Is 200 the magic number similar to automotive pressure

 

[Nandy]

Re: Carrier A/C, Again!

Ok, so the saga continues. I did a quick search in point and it don't seems I have either supplier in charlotte. Exactly what txv size, type or model I need? I might get it at the local supplier.
Thanks for your continued help.

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

Is your TXV in your system adjustable? Is the sensing bulb really tight to the suction line and insulated? Basically the bulb is trying to provide 12 degrees superheat by reading the line temperature leaving the coil and returning to the compressor...If can't open your txv far enough it will restrict refrigerant flow to the indoor coil and the result is high subcooling...Think of a txv like a camera shutter it opens and closes to compensate for load...If yours can't open at all the txv is bad...If it cant open far enough its to small...If it opens to far the result would be a super cold suction line at the coil and flooding liquid back to the compressor...Remember superheat is suction line temperature - suction saturation temp(what the gauge shows in degrees 68.8# = 40 degrees) < 12 degrees = flooding and overfeeding txv > 12 degrees is underfeeding txv...

You are looking for a 70ish # suction pressure with a low 50's suction temperature(Keep in mind this temperature is measured at the coil...You will gain a little heat as you get further away from the indoor coil...If the coil is 52 degrees at the condenser should be like 54 or so...

What I would do is take the bulb off the suction line and put it in hot water to warm it up...Don't use a lighter because there is refrigerant in the bulb and overheating it could break the internals of the valve...If it works right you should see the suction line temperature drop to like 44 or so degrees...If it does that then you need to get the bulb as far away from the indoor coil as you can...Mount it out of the unit at 12 o'clock and insulate it if it...

If warming the bulb doesn't change anything then you have a bad valve...

Most suppliers sell valves that are built custom...They had different power heads and bodies and cartridges...What I would do is get an adjustable externally equalized 3 ton valve and see if it will adjust to give to 12 degrees superheat...If your superheat at that point is > 17 then I would change the cartridge to a 3 1/2 ton and you should get 12 degrees out of that...

For what its worth this system being a 10 seer condenser and a 13 seer evaporator was never going to be easy to set up(I think I mentioned that in an earlier post) I will help you dial it in Its just going to take some time...If you make changes and ask a question I need to know suction temperature and pressure, liquid pressure and temperature(and there is a difference between discharge pressure and liquid pressure) indoor temperature and outdoor temperature

 

[Nandy]

Re: Carrier A/C, Again!

Cool, I appreciate the help. I left yesterday to VA as I have my mother in law in icu. Once I get back next week I will check and get with you.
Thanks!

 

[bigdee]

Re: Carrier A/C, Again!

I agree with hrdwrkingacguy......I was thinking this was a capillary evaporator that left you without options to adjust. Do what hrdwrkingacguy said with the txv sensing bulb and feel the suction return at compressor to try to get the temp down. If it makes you feel better,my system is mismatched (was that way when I bought house) and I have to overcharge to get suction line to sweat. My liquid pressure runs around 275 and it is still running since 1972!. When I bought this place 30 something years ago the compressor was locked up and I had to break it free with a double start kit. I told my wife not to expect much life out of it but it is still kicking...knock on wood.

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

I have to overcharge to get suction line to sweat. My liquid pressure runs around 275 and it is still running since 1972!.

I know you didn't ask but the reason for this is because your piston is to small on the indoor coil...Larger piston and remove some refrigerant will make that system run more efficiently...

 

[bigdee]

Re: Carrier A/C, Again!

I know you didn't ask but the reason for this is because your piston is to small on the indoor coil...Larger piston and remove some refrigerant will make that system run more efficiently...

Thanks but I am stuck because it is a capillary system. This thing is probably 7 seer at best so system replacement is long overdue. Sorry for hijacking thread.

 

[Nandy]

Re: Carrier A/C, Again!

I haven't been able to work on this system but I checked the pdf for my coil and it is a non adjustable txv. I dont have either of those suppliers anywhere close to me but the guy that sold me the coil can probably help. Is a "3 ton aftermarket txv with a equalizer line" all I need to look for? no other designation or parameter needed? I hope this system dont fail any time soon, it could be up to 2 weeks before I can actually do anything.
Thanks...

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

In a supply house you buy the body, the power head, and the cartridge...The body is externally equalized with a 3/8" in and more then likely a 1/2" out...The cartridge is a 3 ton, or possibly a 3 1/2 ton...And you need a R-22 power head...Pretty simple to put together...put a rag on it and braze it in...keep the equalizer line between the coil and the sensing bulb, keep the sensing bulb at 9 - 3 o'clock and make sure its crazy tight and insulated and your GTG...Just need to adjust for 12ish degrees superheat at that point...To a certain extent the line sized in and out are just connections, you don't want the valve to be smaller, but a size bigger on either end wont hurt anything...

70ish degree back temperature, with a 98 degree ambient is a recipe for an overheated compressor...BTW I don't think your compressor amps of 3.5 in a 230v single phase system is right...Are you checking the black wire that goes to C on the compressor? or the brown?

 

[Nandy]

Re: Carrier A/C, Again!

I was reading the black cable going to the compressor. I went and check the numbers tonight but im not sure they are as "real" and the day numbers... Plus I turned the thermostat on the upper 70s to keep it in a more economic temperature. I dont have the psi so these numbers might be useless...

55.4 suction line
78 liquid line
82 condenser fan air
75 at the return
59 out of the master bedroom register
78 inside the house

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

55.4 suction line is a lot different then last time...Check it again when it's hot out...

Suction pressure
Suction temperature
liquid pressure
liquid temperature
indoor temp
outdoor temp

because it wasn't as hot your txv might be hitting the max it can open but there wasn't any load and it runs ok...If in the heat of the day you have a 65+ suction line temp, then you need a bigger txv...

The indoor temp being the same as the liquid line temp is like driving a car down a hill to do a test drive...

 

[Nandy]

Re: Carrier A/C, Again!

Im having trouble locating an adjustable valve mostly because I cant find any online documentation for the valves I have found to make sure they are adjustable. Maybe you guys do have better documentation. These is a sampling of what I have found:
http://cgi.ebay.com/SPORLAN-Y1087-B...221?pt=LH_DefaultDomain_0&hash=item2c5c80b67d
http://cgi.ebay.com/Alco-Thermo-Exp...951?pt=LH_DefaultDomain_0&hash=item4cf47e6e37
http://cgi.ebay.com/1TVM702-TXV-Exp...564?pt=LH_DefaultDomain_0&hash=item45faf6ef64
http://cgi.ebay.com/3-TON-R22-REFRI...843?pt=LH_DefaultDomain_0&hash=item43a793b443

Thanks for the help.

 

[hrdwrkingacguy]

Re: Carrier A/C, Again!

Do you have any HVAC supply houses in your area? ebay might not be the best place to get a valve...