Replyall the coils I replaced were on systems that had txvs, or needed them. I also made sure the airflow was correct, since that can throw off charge.
Professional Member*
Hey BL...
Do you charge the MC systems to SH/SC standards? Or do you carefully measure/calculate and weigh in? I can understand the TXV thing.
The reason I am asking about MC coils is: I am not totally satisfied with the AlliedAir line (not the product, the distribution chain)... thinking of going back to Rheem/Ruud. When I heard they were going MC... it gave me pause. Trying to be sure I am not jumping out of the frying pan into the fire so to say...
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Professional Member*
all the coils I replaced were on systems that had txvs, or needed them. I also made sure the airflow was correct, since that can throw off charge.
Col 3:23
questions asked, answers received, ignorance abated
Professional Member
Hey BL , Whats best when adjusting these units for charge? I am using the chart to charge the units. Also will it happen that the subcool maybe slightly off but based on the chart , the charge is correct? I have one of the units the indoor coil has some slight water dripping off the coil from the middle and falling in the middle of the filter. I know that can be a indication of low charge or low airflow as the indoor coil maybe slightly icing up, although visual inspection didn't indicate that. But everything seem correctly setup. I am wondering the lack of load inside the building is causing the coil to be colder then it should. Indoor the building is a currently empty commercial building. Indoor is 73F. OD 76F. SH 10 SC 13. Suction Temp 50, Liquid Temp 79. Vsat 40 Lsat 92. Low side 120 High side 286. High side would jump up and down between 285-288 ( got measurements from sman3) I did a DeltaT and it came out 22 thats after I increased the airflow from 1405 to 1490, but I never really measured the cfm or Static Pressure , so it may not be totally accurate. (I will later on this week) I remember from class that a DeltaT 22 indicates not enough airflow perhaps. Air handler B6EMMX42K-B and outdoor unit JS4BD-042KA/B.Originally Posted by ga-hvac-tech
Hey BL...
Do you charge the MC systems to SH/SC standards? Or do you carefully measure/calculate and weigh in? I can understand the TXV thing.
The reason I am asking about MC coils is: I am not totally satisfied with the AlliedAir line (not the product, the distribution chain)... thinking of going back to Rheem/Ruud. When I heard they were going MC... it gave me pause. Trying to be sure I am not jumping out of the frying pan into the fire so to say...
Professional Member*
Follow-up to my post:Hey BL...
Do you charge the MC systems to SH/SC standards? Or do you carefully measure/calculate and weigh in? I can understand the TXV thing.
The reason I am asking about MC coils is: I am not totally satisfied with the AlliedAir line (not the product, the distribution chain)... thinking of going back to Rheem/Ruud. When I heard they were going MC... it gave me pause. Trying to be sure I am not jumping out of the frying pan into the fire so to say...
Seems the sales rep at the Ruud shop was wrong... Rheem/Ruud will NOT replace their entire evap coil line with MC coils... rather tub & fin all aluminum coils (same 'N' configuration, with CO tubes for brazing). They should get here later in the Summer or fall, depending on how quickly the existing stock of CO tube/Al fin coils is sold out.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Global Moderator
Use whatever chart is appropriate. Subcool on TXV inside, pressures on piston coils. I noticed some of the subcool targets are lower than before. Just gotta go real slowly!
GA, what about MC outdoors on Rheem?
Professional Member*
So far all I can get out of the tech folks (both Rheem and Ruud, different dist) is many of the package units use MC coils, and some outdoor units use them... they are vague on which outdoor units.
I did get out of the tech guy at Rheem; the MC coils are being manufactured by Delphi (division of General Motors).
I did get a commitment on the new aluminum indoor coils... they are tube/fin, all aluminum, with CO stubs for brazing... and possibly bolt in TXV's. I was told the reason for going all aluminum was formicary corrosion. Asked about outdoor all aluminum (tube/fin) coils... guy got vague and said the issue was formicary corrosion... so why change the outdoor units. Then in the very next breath he said the indoor units would be waaaay cheaper to make all aluminum. I did not poke at him about why not the outdoor units also...
MeThinks they may be doing some testing... and when they decide... we will find out. Just my $0.02...
They did say the entire furnace line was being re-designed; new condensing furnaces will be here by late summer or fall depending on inventory. Main feature of the new 90+ units is the upflow will work left or right also... I guess movable DIM motor and/or various drain options (IMO that was overdue). The new 80% have cut-outs on the sides for venting... not sure I like that... they will be more noisy unless they have a 'firebox' inside. I saw some pics of them... they look like appliances... wonder what they are thinking. I like the way they look now.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Global Moderator
No way. I thought that looked horrible on a Carrier or Goodman back when they did it that way. We have a lot of downflows and often don't have much room for a big old flue pipe coming out the bottom side and up along the furnace. Not to mention how hot single wall pipe gets.The new 80% have cut-outs on the sides for venting... not sure I like that...
Professional Member
I read optimized subcool is between 10-12. So seems like I am in ball park that's also following that chart they gave to base the charge off.
wHen I diE I hOpe gOd haS mErcy oN my SiNful LifE
Professional Member
BL....have you had any problems with the TXV going bad on the microchannel coils from Nordyne?
wHen I diE I hOpe gOd haS mErcy oN my SiNful LifE
Professional Member
Well Ill be going back to the job I did on Tuesday. I also did not know u had to pull the valve core out of the equalizer tap. The system seemed to be running great. 10* subcool, 12* superheat, 20* split. I guess it all makes sense tho, there isnt a depresser on equalizer nut. What will happen if I dont remove valve core? There wasnt a tag saying so.The biggest problem I've seen is installer error on indoor coils, between the piston size and an epic run of retardation at our shop that had me looking at every MC coil we installed with a txv kit, they(our guys) never pulled the valve core from the equalizer tap....
Last edited by Carbent; 06-13-2013 at 05:58 PM. Reason: Wheres my sign
Professional Member*
The valve won't sense evap pressure and will shutdown causing high superheat
Professional Member*
There was a thread showing pic of a big yellow tag telling you to remove the schrader that they had to remove?
Professional Member
I did the jjob prior to reading this thread
Professional Member
Its in this thread! loll on pg 2. I just removed the TXV and replaced it today... the strainer was partial clogged with debris and was causing a restrictions. I saw it after I removed the old one. LOL, was very frustrating with my first TXV change out. ROFL
wHen I diE I hOpe gOd haS mErcy oN my SiNful LifE
Professional Member*
Was the debris oxide by chance? Because we just had a discussion where some members didn't think brazing with
Nitrogen was all that important.
Professional Member*
I'd like to hear or see what copper oxide will do to the microchannel coil passages......I guess time will tell.
Was the debris oxide by chance? Because we just had a discussion where some members didn't think brazing with
Nitrogen was all that important.
Professional Member
It sure was. Kinda shame on me...well my friends... whom brazed all the original lines. Although I did mention to him to do it but he was being an A-hole about it that time. Actually more ignorant. Then it came back to haunt me! ROFL. I did use nitrogen today.
Was the debris oxide by chance? Because we just had a discussion where some members didn't think brazing with
Nitrogen was all that important.It seemed it was 1/3 clogged. The unit kept freezing. I saw it froze from the TXV all the way to the compressor. ROFL. And my suction won't go up at all. It floated around 90-95 psi and kept the saturation temp down. It was a real roll coaster ride.
wHen I diE I hOpe gOd haS mErcy oN my SiNful LifE
Membership Chair/ARP Committee / Professional Member*
Clean the line well and shiny all the way around with sand cloth.
Use a clamp-on access valve.
Remove the o-ring seal.
Clean the inner clamping areas with sand cloth.
Clean it with brake cleaner or other solvent.
Dry it and re-install the little o-ring seal
Install the clamp-on valve with J/B weld smeared lightly on all the inner clamping surfaces Outside the little r-ring seal.
Wait 24 hours before running the piercing needle in.
Put the seal cap on, lightly wire brush the whole valve, and paint it with engine enamel.
They last a very long time installed that way.
But don't ever let anyone know you have done this or they will call you a hack. <g>
PHM
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PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
Global Moderator
Knock on simulated wood but we've found the Danfoss TXVs Nordyne uses to be more reliable than some of the other brands.
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