what size orifice to use with 407c in a 5 ton

I work at a University, and am fighting a reoccurring issue with a residential split system non keeping up when temps become into the mid eighty's and upwardly.

Unit of measurement is a 3 ton R410 I.C.P. unit, fixed orifice.
Indoor unit calls for a 070 piston. This piston in it is 067. Condenser only references TXV, doesn't specify a piston size.
Subcool is approx x, superheat is in the 40's. Comp amp draw is below RLA, suction pressure is low (gauges show a twenty degree gyre, merely no ice or sweating is occurring), and head pressure is slightly low.

According to my research, every bit I'm non familiar with a "normal subcool, high superheat" scenario, this indicates a "mild restriction with excess refrigerant", which makes sense because the guy earlier me crammed freon in thinking it was but low.

And so the piston is a 067 instead of a 070, but the evap coil is also fairly dirty, AND the filter drier looks like the installer never replaced it when he did the R-22 to R-410 install. I'm wondering if these 3 issues could be compounding to create a "mild restriction" like situation where the unit loses efficiency when the temps get higher. So my main question is, would you replace the piston with a 070? Obviously I'll clean the evap scroll and supervene upon the drier, but I'1000 wondering if I should get ahead and wait for a 070 piston to get here as well, or is information technology OK to just put the 067 back in and let it go. I was thinking most a TXV, merely this thing has very little room for one and I don't desire the arrangement down any longer than it needs to exist, as the apartment is occupied.

Thanks for any advice you tin give.

Usually, the right sized piston comes with the new condenser. Me personally, I change the piston everytime unless it'south an exact lucifer in the gyre already. Seeing that you lot switched from an R22 to a R410A system, it should accept been changed anyway. If y'all tin get a .070 piston, y'all should alter it. Change the filter drier and clean the inside coil. Check your pressures afterwards that.

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02:22 PM

I would take some before and after readings, to compare such as temperature difference, pressures, amp.reading etc at similar OD temperatures if possible.

everything is low even temp split.. I wonder what that means.

ten� subcooling is kind of low for a system with fixed metering, and certainly doesn't hint at a brake.

All of the symptoms you mentioned point to an under accuse.

A 0.067 orifice is about right for a 3 ton 13SEER R-410A system, or at least really shut, depending on which manufacturers chart you look at.

Mostly you should ignore the orifice size listed on the indoor coil, and become with what the outdoor unit calls for, which in this case is a TXV.
Since you don't have a TXV, the next closest thing you tin can do is look at a generic chart, and most of them I have at hand testify 0.067 to 0.070, so there isn't actually anything significant to be gained by irresolute the orifice.

what ICP model # ? If its a 14seer go with txv subsequently cleaning evap/blower wheel & replacing drier . If its a 13 so with a clean scroll shouldn't exist a problem with a 67 vs a lxx

Quote Originally Posted by mark beiser View Post

10� subcooling is kind of low for a organization with fixed metering, and certainly doesn't hint at a brake.

All of the symptoms y'all mentioned betoken to an nether accuse.

Yeah, yesterday, after replacing the drier, cleaning the evap roll, and ensuring the piston was make clean, I got the system back up over again and I ended upwards with thirty degrees superheat, six degrees subcooling, still with a 20 degree evap coil but 225psi on the loftier side (with an indoor temp of 71 and outdoor of 75). And so now I'one thousand at the indicate of adding freon to smooth everything out. When I took the line apart to get to the piston, I BARELY put force per unit area on the crescent wrench and the nut turned. Well-nigh similar information technology was just beyond hand-tight. I might have had a slight leak in that location. This unit of measurement has been giving them problems for a few summers now. I'm wondering if it's been leaking downward in the winter and so the guy before me was just charging information technology up and leaving.

I was taking a 10 caste subcool to exist "normal", because when I worked for a residential service HVAC company, they ever made usa "accuse the unit to 10 degrees subcool unless unit specifies otherwise". Based on the unit'southward chart on the panel, with our outdoor temps fluctuating wildly in TX correct now, 10 degrees subcooling was pretty shut to what it wanted. At this point I'm only going to adjust the charge and monitor it through the summer.

Quote Originally Posted past oldguy1949 View Post

what ICP model # ? If its a 14seer go with txv after cleaning evap/blower bicycle & replacing drier . If its a xiii then with a make clean ringlet shouldn't exist a problem with a 67 vs a seventy

Hmm, I'll have to check that out. Knowing this school, information technology'south a 13 SEER considering of pricing, haha. That's definitely why information technology's ICP.

Quote Originally Posted past BrownPigeonSwag View Post

I was taking a x degree subcool to be "normal", considering when I worked for a residential service HVAC company, they always made us "accuse the unit to 10 degrees

I would just like to know why you're concerned well-nigh SC on a piston system, could you lot delight explicate.
Thank you.

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The Lennox charging charts always used subcool for pistons. Ran xiv-16 at 65 ambient and went down as it got hotter out No idea why they have to be so ass backwards from everyone else.

every bit you know sc cool should be about 15 on piston depending on ambient weather of class.

Quote Originally Posted by Mr Nib View Post

I would just like to know why you're concerned about SC on a piston system, could you please explain.
Thank you.

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Quote Originally Posted by Mr Bill View Post

I would just like to know why you lot're concerned about SC on a piston organization, could you please explain.
Thanks.

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A few reasons. I is I always get mixed upwards on when you demand what reading. Superheat only for pistons? Or is it contrary? Or should I only get both? My HVAC background comes from active duty air force, and while they did teach us about superheat and subcool, I can safely say we hardly EVER used it. Honestly, most of my experience was irresolute fan motors, replacing pumps, and installing compressors. Not very much charge adjustment, so I never really got the whole superheat/subcool stuff memorized. And when we did do freon piece of work, we'd merely accuse it to a 38-xl degree evap coil, check supply/return air temp split, and go. And that was about Always sufficient, even after doing yearly followups on the equipment nosotros'd worked on. I always idea, "Hey, this HVAC stuff is easy." And then I got out and got hired past a service company and they wanted to make everything all complicated. I haven't be able to fix an A/C since.

As well, the master reason is that when a unit gives me some really strange symptoms that come and get, specially with inefficiency, and it'southward non electrical, I like to just have all the data. Well-nigh every troubleshooting chart I look at asks for superheat, subcool, amp depict, temp splits, outdoor and indoor, temp. So I merely endeavour to get ALL of that, regardless of expansion device. Can't hurt, as far as I'grand concerned.

Always take both. As each one can also point to a problem the other doesn't isn't showing. but generally SH for piston, and SC for TXV.

OK, well subsequently getting back over in that location, I think I may take the situation figured out, with help and communication from this thread.UPDATE:
My data, when input into my troubleshooting chart I employ, pointed to a "mild restriction with excess refrigerant". That is all fine and swell, except for the SOURCE of the information was incorrect. I'd misread the condenser charging chart, and incorrectly calculated x degrees subcooling every bit my "required subcooling". Later some of your comments, I reread through the equipment literature and discovered the actual subcooling should be 14 degrees. Then, instead of a "normal subcool/high superheat" condition, I had a "low subcool/high superheat" condition (undercharge). I couldn't find anything indicating how to accuse this unit based on superheat, equally it only said to refer to condenser charging nautical chart and get by its piston size, only then the condenser says TXV and doesn't mention anything nearly charging by superheat. And so I said spiral all this bullcrap and shoved refrigerant in it until I had a 40 degree evap coil, then checked and found I had correct at 14 degrees subcool with about 16 degrees superheat.

Now if I can merely verify what the superheat should exist on this unit, I think I'll have information technology nailed downwards. The room render temp is about 73 (Tstat shows room temp at 71), and outdoor air temp is about 77, with a 40 degree evap coil.

Need to know indoor wetbulb to calculate what the Sh should be. As information technology changes by the indoor wetbulb and outdoor dry seedling temp.

Quote Originally Posted past BrownPigeonSwag View Post

Unit is a three ton R410 I.C.P. unit, stock-still orifice.
Indoor unit of measurement calls for a 070 piston. This piston in it is 067. Condenser merely references TXV, doesn't specify a piston size.
Subcool is approx 10, superheat is in the xl's. Comp amp draw is below RLA, suction pressure is low (gauges show a 20 degree curl, but no ice or sweating is occurring), and head pressure is slightly low.

Organization Info /Type:

Heating type (EH, Gas, Propane, Oil)
Equipment (Packaged, Split)
Cooling but, Oestrus Pump,
Metering device (TXV, Cap tube, orifice)

Here is a list of operating data to evaluate Air conditioning cooling performance:

RA temp DB
SA temp DB
RA temp WB (to calculate ID Relative Humidity...Target 50% RH)
Condenser air leaving temp
OD ambience (Condenser air inbound temp)
Condensing temp (not pressure...from PT Chart)
Liquid line Temp
Suction line temp at Evaporator outlet (to calculate evaporator SH)
Evaporating temp (not Pressure...from PT Chart)
Suction line temp at Compressor (to evaluate compressor cooling Maximum temp at normal operation conditions = 70 deg F)
Belch line Temp (Oil breakup if over 270 deg F...Spit test)

Calculations:
Evaporator air split =#1 - #2
Condenser air split up =#four - #v
Subcooling = #6 - #7 (10 to 15 deg F Normal for any type of metering device)
Superheat = #8 - #nine (x-12 deg F for TXV and for Cap tube or orifice at NORMAL operating loads)
Suction line temp at compressor (at least lxx deg F for compressor cooling and no less than 5 deg F SH at compressor inlet to foreclose liquid flooding.)

Quote Originally Posted by beenthere View Post

Demand to know indoor wetbulb to calculate what the Sh should exist. Every bit information technology changes by the indoor wetbulb and outdoor dry bulb temp.

I concur, however in my ARIZONA feel, I have NO feel in high ambience humidity.
Also I would add that airflow matters a lot. The testing by Arizona Public Service (utility) adamant that the average airflow of the average Air-conditioning in their testing was nether 325 CFM per ton which they cited as the manufacturer's minimum airflow.

Quote Originally Posted by lynn comstock View Post

I concur, however in my ARIZONA experience, I take NO experience in high ambient humidity.
Likewise I would add that airflow matters a lot. The testing past Arizona Public Service (utility) determined that the average airflow of the average AC in their testing was under 325 CFM per ton which they cited as the manufacturer's minimum airflow.

Yeah, the SH charts are ready with a somewhat narrow range of CFM.

Quote Originally Posted by beenthere View Post

Yes, the SH charts are prepare with a somewhat narrow range of CFM.

Clarification:
The SH charts utilize to cap tube and orifice systems only. The TXV systems establish a stock-still SH once there is plenty refrigerant to fill the liquid line...Then SC tells you when to cease calculation refrigerant. I'd say, xv deg F is max.

Quote Originally Posted by BrownPigeonSwag View Post

OK, well later on getting back over there, I recall I may take the situation figured out, with aid and advice from this thread.

UPDATE:

My data, when input into my troubleshooting nautical chart I utilize, pointed to a "balmy restriction with excess refrigerant". That is all fine and dandy, except for the SOURCE of the data was wrong. I'd misread the condenser charging chart, and incorrectly calculated x degrees subcooling equally my "required subcooling". After some of your comments, I reread through the equipment literature and discovered the bodily subcooling should be 14 degrees. Then, instead of a "normal subcool/loftier superheat" condition, I had a "low subcool/high superheat" status (undercharge). I couldn't notice annihilation indicating how to charge this unit based on superheat, as it just said to refer to condenser charging chart and go past its piston size, but then the condenser says TXV and doesn't mention anything nearly charging by superheat. So I said screw all this bullcrap and shoved refrigerant in it until I had a xl caste evap coil, then checked and found I had right at 14 degrees subcool with about 16 degrees superheat.

Now if I can simply verify what the superheat should be on this unit, I call up I'll have it nailed downwardly. The room return temp is about 73 (Tstat shows room temp at 71), and outdoor air temp is well-nigh 77, with a xl caste evap coil.

Superheat and subcooling look spot on. Record what y'all have now along with some static pressures to confirm proper air flow. Bank check the system again when it is xc* exterior to make sure it is non overcharged. You should then have a superheat no lower than half-dozen.

what size orifice to use with 407c in a 5 ton

067 sized piston, unit of measurement calls for 070. Is this enough to cause issues?

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