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Author Topic: calibrated orifice DFS2A  (Read 20025 times)

Offline JWWebster

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Re: calibrated orifice
« Reply #20 on: June 14, 2009, 11:15:41 PM »

What are ya working on is it a walk in cooler or a ice machine or central air? WTF is it you are trying to charge? Get the suction pressure up to 68.5 PSI and that will give you 40 degrees F across the a-coil. that is a good thang. If you think the head pressure is getting too high watch your amp meter. This ain't rocket science. O0
« Last Edit: June 14, 2009, 11:22:54 PM by JWWebster »
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Offline patvac

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Re: calibrated orifice
« Reply #21 on: June 14, 2009, 11:22:25 PM »
i think you guys call it a mini split. 12000btu a/c unit where the condenser is outside to ground level and the evaporator is on the second floor

Offline Icehouse

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Re: calibrated orifice
« Reply #22 on: June 15, 2009, 01:29:21 PM »
When evacuating the system with both high and low side hoses connected to the compressor,
1.Open high side hand wheel on gauge manifold.
2.Leave low side hand wheel closed on gauge manifold. Start vacuum pump.
3.Observe low side gauge (should go into vacuum).
4.If it does not go into a vacuum reading, you have a restriction.
5.Continue operating till you have reached 29" hg. vacuum although using a micron gauge is the proper way (500 microns).
6.Let unit stand for 5 minutes, should be no change.
7.A slow rise indicates moisture (longer evacuation time).
8.Rapid rise, you got a leak.
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline JWWebster

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Re: calibrated orifice
« Reply #23 on: June 15, 2009, 02:27:30 PM »
I bet it has something to do with how the pipes connect from the evaporator to the outside condenser. How did you make up the connections?
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Offline Icehouse

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Re: calibrated orifice
« Reply #24 on: June 15, 2009, 03:32:19 PM »
I bet it has something to do with how the pipes connect from the evaporator to the outside condenser. How did you make up the connections?
>:( He mentioned that at the start. :tickedoff:
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline patvac

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Re: calibrated orifice
« Reply #25 on: June 15, 2009, 09:43:01 PM »
1/4 size pipe for pressure(copper)
1/2 for succion (copper)
they are shape like an Z but on the side

Sorry if i misconduct you
If needed i can add a picture

Offline JWWebster

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Re: calibrated orifice
« Reply #26 on: June 15, 2009, 09:55:30 PM »
Please add a pic because this is all becoming perfectly clear now. Your tubing is too small. The minimum is 3/8ths tubing for the hi side and 5/8th for suction.
« Last Edit: June 15, 2009, 09:59:06 PM by JWWebster »
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Offline Icehouse

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Re: calibrated orifice
« Reply #27 on: June 16, 2009, 04:37:41 AM »
Please add a pic because this is all becoming perfectly clear now. Your tubing is too small. The minimum is 3/8ths tubing for the hi side and 5/8th for suction.
  :) JW, he is giving "Nominal" size which is inside diameter. Air Conditioning uses outside diameter  which is larger by (1/8). Therefore 1/4" ID is 3/8" OD and 1/2" ID is 5/8" OD.
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline Icehouse

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Re: calibrated orifice
« Reply #28 on: June 16, 2009, 05:05:51 AM »
Let's look at "old school" charging. That is "Ambient Temperature" plus 30. Convert this reading using a "Pressure-Temperature" chart to pressure. Example 80*F + 30 = 110* F. Assuming the refrigerant is R-22, you will read 225# (actually 226.4).
Low side reading should be equivalent to 40* F evaporator temperature, in this case 69# (actually68.5).  O0
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline Repair-man

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Re: calibrated orifice
« Reply #29 on: June 16, 2009, 05:20:28 AM »
Since he is dealing with very low ambient temps, this system may not operate correctly under 68 degrees outside. He really needs a heat pump capable of defrosting itself.
"It's only expensive if someone else fixes it for you" -
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Offline Icehouse

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Re: calibrated orifice
« Reply #30 on: June 16, 2009, 05:39:11 AM »
Since he is dealing with very low ambient temps, this system may not operate correctly under 68 degrees outside. He really needs a heat pump capable of defrosting itself.
That or a professional.  O0
NATE, NCCER, PHCC,HVAC Certified Instructor
Member RSES, US Army Refrigeration Specialist(Retired), Former Refrigeration Teacher NYC Board of Ed.
a tragedy has happen to me : http://web.me.com/zenzoidman/Bobice/

Offline JWWebster

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Re: calibrated orifice
« Reply #31 on: June 16, 2009, 09:32:20 AM »
Did the quarter inch tubing come with the mini split or was that something you got on your own Pat?
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Offline maypo52

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Re: calibrated orifice
« Reply #32 on: July 09, 2009, 07:47:13 AM »
I was following this post because I have a similar problem with freezing, and I think your comment about the indoor and outdoor temps being the same is my problem. I just had a couple of questions. If the outside temp is say 70, and the thermostat is set for 78 but the temp inside where the thermostat is 80, so the unit is still running trying to drive it down to 78, but the indoor temp at the "A" frame which is in the basement is about 70, Is that the scenario that will cause the freezing of the "A"frame? Is there anyway to prevent the system from freezing up? When you said "block off the condenser" did you mean to cover the vent on the outside unit to prevent the cooler outside air from flowing over the coils?  Hope that made sense to you. Thanks for any help you can provide.

Mark


:) This system will not operate correctly because the "outdoor temperature" is nearly the same as the "indoor temperature".
The unit is so efficient that too much refrigerant is condensing in the condenser. Remember that this is a critical charged unit, therefore the condenser,evaporator,suction line and liquid line will contain the proper amount of refrigerant. If at anytime there is an unbalanced condition, the system will fail to operate in the prescribed manner. The condenser has too much refrigerant due to the low ambient therefore starving the evaporator thus resulting in lower pressure which results in lower temperature (frost accumulation).
To remedy this situation, block off the condenser allowing the head pressure to build up to a corresponding pressure of a 95*F day. You will then notice the suction pressure will also rise and now is the time to check the superheat.
My philosophies:

If it ain't broke, don't fix it and When all else fails RTFM (read the "funny" manual)

Offline JWWebster

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Re: calibrated orifice
« Reply #33 on: July 09, 2009, 08:28:44 PM »
If you was in someplace colder like Nova scotia then you might want to jacket the outside unit to mimick the outside temp of summer. I wish he would say who concocted that smaller tubing idea. I can already tell ya the answer. The tubing was suppiled by you and since you went cheap with a minisplit you decided to go cheap with the copper. Just a guess.
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Offline patvac

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Re: calibrated orifice
« Reply #34 on: July 09, 2009, 09:28:26 PM »
hi, jw the mini slip i bought was a kit.
condenser, compressor, pipping and sleeve to go over it.it cost over 1200$because a friend got a discount for me of 300$. Local shop around sell it 2000$ install. After the test with the jacket and risses of temp over 85 degree peaks at around 95. Units work perfect (it's cycling on and off, no freezing of the coils). Unlikely i dont have the tools suggested by icehouse  but definitly it's a charging problem( bad gas quantity)I would like to go the way superheat  and ...)
to bad i dont have the special tools...

thank for your help and your patience

Offline JWWebster

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Re: calibrated orifice
« Reply #35 on: July 09, 2009, 10:42:26 PM »
Je suis heureux vous l'ai obtenu fixe!
:D
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About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair

Offline patvac

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Re: calibrated orifice
« Reply #36 on: July 10, 2009, 04:42:31 PM »
thank you