The fixed orifice expansion device
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- čas přidán 9. 07. 2014
- This one covers how the fixed orifice expansion device works. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits. - Jak na to + styl
Thank you for posting this video GFM!
Welcome
GFM
Good explanation!
good refresher... Nice goodman piston by the way :)
Hey gray do you need to pump down the system to replace it or it can be replace with regular freon charge?
Question: If you needed to open the system for some reason, add dryer or pull the evaporator or...... Could you close the outlet on the compressor and suck the system down with the compressor and them close the suction side and open the system?
First would this be legal and 2 how low would you suck the system down to. I remember seeing a tech do this many years ago when he started a system and found a leak. How would this be done legally if it can be done. Thanks for your time.
amtpdb1 You can pump the system down if it has valves on the condensing unit. Here is a video on how. czcams.com/video/qBTHLHh3394/video.html This, of course is only useful for working from the liquid line out of the condensing unit and beck thru the suction line to the outdoor unit. When the repairs are done the portion of the system you have worked on must be evacuated using a vacuum pump before opening the valves and putting the system back in operation. Because you are not dumping refrigerant to the atmosphere, there are no laws violated that I know of. Hope this helps.
GFM
voice of Frank Hill? "king of the hill"
hi, if head pressure goes up to 350 and suction pressure stays at 100 in your example. would MORE refrigerant be fed into the evaporator because of bigger pressure difference? thanks.
Yes. Refrigerant flow, superheat and subcool are all controlled by the pressure difference.
GFM
You painted your work bench !
Say you bought a new condenser and evap coil. the evap coil has that orfice installed, and there is one in a baggie hanging off the condenser. Which one should i use?
Whichever one the manufacturer's instructions say to use for that combination.
GFM
I have a question on how one would select a specific size orifice.....I have a 2.5 ton Rheem r-22 condenser that was hooked to a York slab evaporator that employed a #59 orifice......I am replacing the slab coil with either a 2.5 or 3 ton "A" coil (depending on what I can find locally) ---wondering how I determine what size orifice to use with the new coil....dont really want to go to TXV - its a 10 SEER unit and dont see the benefit of TXV here.
Any info or place you can send me much appreciated - will be doing this soon since system is down from evap leak and its hot here
The fixed orifice is all manufacturer specs. In your case you have a mismatched coil and outdoor unit. The best solution is a TXV.
GFM
thank you very much for your kind reply.
Welcome
GFM
Hello dear! i looking for a table or something has the capabilities of each number from the fixed expansion device.
There is no chart for all these orifices. They are of different design for different manufacturers, so the manufacturer is the only source.
GFM
Is the only way to tell if it is restricted to take it out. For some reason I have problems with finding the restrictions.
Pretty much. low suction, low head, low delta T, adding charge makes no difference, Usually that is the problem. Other possibility is plugged drier (should be a temp diff across the drier). Subcool should go up as charge is added but no corresponding rise in suction pressure. hope this helps.
GFM
I have a mismatched 1995 Bryant 10 SEER coil and a 2015 Trane 13 SEER condensing unit MOD # 2TTB 3048A 1000 NA 4T R22. The orifice doesn't let enough refrigerant through under heavy loads and I would like to change it to a TXV. Do you have any recommendations on size or model number? Do you think an external equalizer is necessary? Do I need one that will bleed off the pressure during the off cycle? Thanks.
The system will never match properly.
To answer your questions, size is 4 ton. external equalizer is necessary. You may need either a hard start kit or a bleed TXV.
GFM
Hi do you know how to fix the threads in an aluminum coil where the Orifice is secured
It means a new coil.
GFM
Hi, I'm working in my home ac, after l lost all my freon r22 due to a leak in the outside condenser, I'm looking to recharge with a compatible and eco friendly freon. I watched your video and went and look the evaporator and came across with txv valve with 2 check valves, before and after the txv and it has orifice piston #40. It's a 2.5 ton Rheem unit with a 3 ton out side condenser. does it need all these components? or can l keep just the orifice piston and remove the txv?, btw, the txv has a equalizer as well. Thank you
What size of piston should I use for a 4 ton 410 unit?
There is no right answer. You should be looking at manufacturer instructions including evap size, and condensing unit model.
GFM
Hi GFM. I'm helping out a friend whose evap coil is leaking. It is a superior coil which isn't being manufactured anymore. The old coil was 3.5 tons and the cond. is 3 tons. I put in an Armstrong 3.5 ton coil. The problem I have is I cannot find anything on the condenser as to what size piston to use. Do you have any piston charts or any suggestions for the best size piston. My research on line is leading me the conclusion that I should use a #73 piston. It is an r22 system. It would have probably been best to replace the whole system but money is tight as his wife is recovering from cancer treatments. Thanks for your help.
+johnmiller102 I do not have any charts. About all you can do is use target superheat for charging and change pistons if necessary. Hope this helps.
GFM
Ok. Thanks. Would it be correct that if superheat is too low and the system is charged correctly than the piston is too large? If too high than the piston is too small? My concern is if the piston is too large I might end up slugging the compressor.
+johnmiller102 You are correct.
GFM
Hi sir i have reheem hvac evaproter not cooling full when unit on only hoff evaproter pipe going not fully coil sir whats we do.
One of the distribution tube may be blocked.
GFM
Thanks you sir
GFM is it safe to say that all pistons are capable of being a check valve for a heat pump......?
All that I have seen will work.
GFM
grayfurnaceman got it....thanks👍
I have a unit that has 3 pounds of freon. No leak. Evap is freezing up.. if I over charge the unit.. low side remains in fessing temperatures...air flow is good. Should I question the fixed orifice or the compressor?
I would look at the orifice first. Assuming the superheat is high.
GFM