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Old 07-29-2012, 11:13 PM   #61
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Adding R-22 increases suction temperature???


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I have digital bathroom scale but also have a Ohaus dual beam balance that goes to ~45 lbs (20+ kilos), and it is very accurate.
That scale is ok if your cylinder is a small 30 pound cylinder, and you aren't over charged by a lot.

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Old 07-29-2012, 11:15 PM   #62
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Adding R-22 increases suction temperature???


http://www.ebay.com/itm/New-110lbs-5...-/390435321155

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Old 07-30-2012, 08:38 AM   #63
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Adding R-22 increases suction temperature???


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Bought it. Thank you.
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Old 07-30-2012, 09:15 AM   #64
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Adding R-22 increases suction temperature???


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When I supect overcharged system (not saying that is it as others may disagree but that would be my guess without being there) I purge into reclaim cylinder from liq line. due it in short burst. allow at least 5 min between burst may be even 10 to be sure. check the system after waiting the 5/10 min. repeat the procedure unit your suction starts to fall. If you are overcharged you will let a lot out any suction will remain the same or near the same. you will see the high pressure drop as you let it out. Once you bring the low side down past where it should be you can then charge the system. Forget the chart as I think you wet buld is off somehow. I also supect you have a txv but you say you don't and I am not there. A piston metering device would typically increase the suction pressure as the discharge pressure increased. I think you are extreemly overcharged and your indoor coil is all liq vs gas. Once you are sure your charge is low then begain recharging slowly. Get the super heat to 8 to 12.
After removing some refrigerant a couple of times, last evening while outside temp was still over 100 I ended up with Suction Pressure 70 and Liquid Line Pressure 285. This morning with outside temp 78, I have Suction Pressure 60 and Liquid Line Pressure 215.

Indoor wet-bulb into the evaporator is 52. Superheat is off the Payne chart and -1 using Doc's formula.

Suction Pressure 60 equates to 36F. Measured Suction Line temp is 38, resulting in 2F Superheat. Not sure if I am under charged yet or not, but at least out of danger. My Promax RG5000 ships today. Should be here around Wednesday. So I am going leave things as they are, now that I am out of the danger zone, until the Promax arrives.

Paul

The house is a cold 70F.
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Old 07-30-2012, 09:17 AM   #65
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Adding R-22 increases suction temperature???


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Originally Posted by turnermech View Post
try to wrap your same theromocouple with wet rag and stick it in the return see what you get that way
I actually have a wet-bulb thermocouple on its way to me. Shipped last week via USPS. Should be here any day now.

I also have a digital Temp/RH meter on its way here. Also shipped last week.

Will report my findings.
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Old 07-30-2012, 11:32 AM   #66
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Adding R-22 increases suction temperature???


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Originally Posted by Doc Holliday View Post
Still no luck, huh? Sucks. Best bet would be what these guys have been saying, recover and weigh in charge. What is the system charge? It should say on the service panel.

And btw, that weigh in charge is good for the compressor, about 15' of line set and the evaporator. Don't be surprised if you have to add to that weight as you will most likely have to with a longer line set. You'll be dealing with superheat again.

If it were me I'd simply pump the system down, remove shraeder cores, shoot some nitrogen into the line by way of ONE side, either low or high and again, with the shraeder cores removed, and watch the other side's needle to make sure it comes up as well. Then close off the open side and open the other and back and forth to make sure there is no restriction. In other words, adding through one side the other side should rise as well. If not or noticeably too slow, restriction.

Let the nitrogen sit in there for about ten minutes to make sure there aren't any leaks which I wouldn't believe there to be at this point but still...then I'd remove the hoses from both valves and let the nitrogen fly out (taking any possible debri with it), put back in the shraeder cores, vacuum, open valves, turn system on and see what happens.

Then if still the same is when I'd get to recovering and weighing in the charge. I as well don't believe it to be overcharged but rather a restriction at this point.
Thanks for the suggestion Doc. Unfortunately I don't have nitrogen; and I just checked with a local welding supply store, and, although they have nitrogen and rent tanks, they don't rent the ~$125 regulator. I'll look into this to determine what other alternatives are available for nitrogen.
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Old 07-30-2012, 07:03 PM   #67
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Adding R-22 increases suction temperature???


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Originally Posted by psehorne View Post
After removing some refrigerant a couple of times, last evening while outside temp was still over 100 I ended up with Suction Pressure 70 and Liquid Line Pressure 285. This morning with outside temp 78, I have Suction Pressure 60 and Liquid Line Pressure 215.

Indoor wet-bulb into the evaporator is 52. Superheat is off the Payne chart and -1 using Doc's formula.

Suction Pressure 60 equates to 36F. Measured Suction Line temp is 38, resulting in 2F Superheat. Not sure if I am under charged yet or not, but at least out of danger. My Promax RG5000 ships today. Should be here around Wednesday. So I am going leave things as they are, now that I am out of the danger zone, until the Promax arrives.

Paul

The house is a cold 70F.
I still am having some trouble with your reading. suction pressure of 60 with line temp of 38. something seems wrong. with a suction pressure of 60 you would seem to be low on charge (but please don't add more) you would be 36 at the start of the coil but to be 38 at the suction line service valve can't in my mind be correct. are you taking this temp near the low side line set port (like with in a few feet)?
Try to test your thermometer by placing it in a water ice mixture and see if you read 32. Test you gauges by checking the pressure in your R-22 tank and then testing the temp of the tank (once you prove your thermometer). then use P/T chart to see if you gauges are correct. test both gauges
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Old 07-30-2012, 11:12 PM   #68
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Adding R-22 increases suction temperature???


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Originally Posted by turnermech View Post
I still am having some trouble with your reading. suction pressure of 60 with line temp of 38. something seems wrong. with a suction pressure of 60 you would seem to be low on charge (but please don't add more) you would be 36 at the start of the coil but to be 38 at the suction line service valve can't in my mind be correct. are you taking this temp near the low side line set port (like with in a few feet)?
Try to test your thermometer by placing it in a water ice mixture and see if you read 32. Test you gauges by checking the pressure in your R-22 tank and then testing the temp of the tank (once you prove your thermometer). then use P/T chart to see if you gauges are correct. test both gauges
For measuring the suction line temperature I have been using a digital infrared thermometer. I couldn' seem to get good contact with a thermocouple strapped to the pipe with velcro.

I have set up a ice water bath and have three thermocouples in it connect to two instruments. The closest any of them read to 32 is 33.2. However, the infrared reads 32 when held about three inches above the water bath. It read a degree or two less when held really close; presumably because it it measuring an ice cube. At three inches away the pattern is presumably broad enough to capture the average of water and ice cubes and I believe is more likely to reflect the correct temperature.

Bottom line the infrared thermometer that I have been using appears to be accurate. However, I will fashion some type of clamp other than velcro to attache a thermocouple and see what reading I get. (Keep in mind that all three thermocouples and instruments they are attached to consistently read higher than 32. It is hard to get consistent reading. Stirring the water bath changes the readings - varying from 33.2 to ~35)

Once again. thanks for your staying power. This experience has been very educational and enjoyable - despite the wild good chase adding R-22 when the system was already overcharged. No one is at fault here. As you mentioned it is very easy to be fooled when reading are distorted when a system is overcharged.

Paul
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Old 07-30-2012, 11:14 PM   #69
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Adding R-22 increases suction temperature???


My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.
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Old 07-30-2012, 11:35 PM   #70
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Adding R-22 increases suction temperature???


any mixture of water and ice will be 32 every drop of water and every inch of ice. this will stay constant until all ice is melted or all water is frozen. This is handy fact of science so mixing should not matter, ice temp will be same as water temp. You would need to let the two adjust to one another several min before testing temp

What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.

Last edited by turnermech; 07-30-2012 at 11:42 PM.
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Old 07-30-2012, 11:40 PM   #71
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Adding R-22 increases suction temperature???


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Originally Posted by psehorne View Post
My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.
I have never need to use one in my career as of yet. i bought one years ago and never used it before one thermomete broke. I fixed it and it somehow broke again.

When I need to know wet buld I put a digital thermometer in the return duct of a running system with wet cloth on the sensing probe.
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Old 07-30-2012, 11:59 PM   #72
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Adding R-22 increases suction temperature???


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My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.
Sling psychrometer provides the following readings:
  • Dry bulb 25C
  • Wet bulb 17C
  • wet bulb depression is 8C

The chart says this is [EDIT:50% RH should be 44%]. I find this hard to believer. Our local airport is reporting
  • Temp 31C
  • Dew Point 15C
  • Barometric Pressure 29.94
which translates to 38% RH according to http://easycalculation.com/weather/w...calculator.php and my Psychrometric Chart.

I find it hard to believe that the humidity inside my air conditioned house is higher than the outdoor humidity.

However, if I use the above 17C (63F) and the current outdoor temperature of 88F, the Payne Chart shows required superheat of ~8F.
Current measurements at the heat pump are:
Suction Line psi/temp: 65/40
Suction Line temp: 45
Superheat: 5

I think from what I have learned this indicates that I am still overcharged a bit. Correct?

Last edited by psehorne; 07-31-2012 at 12:20 AM.
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Old 07-31-2012, 12:09 AM   #73
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Adding R-22 increases suction temperature???


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Originally Posted by turnermech View Post
I have never need to use one in my career as of yet. i bought one years ago and never used it before one thermomete broke. I fixed it and it somehow broke again.

When I need to know wet buld I put a digital thermometer in the return duct of a running system with wet cloth on the sensing probe.
I have a wet-bulb thermocouple on its way to me. In the mean time I can try your method, which some, perhaps you, suggested earlier in this thread. I just had not gotten around to it yet. (Besides, being fond of vintage technology, I just had to have a sling psychrometer.

I could have mentioned early on that my primary reason for venturing into this DIY HVAC journey is mostly because I have always had a thirst for knowledge and wanted to understand how these systems work. (Of course, that is not the reason I gave my wife. ) I have enjoyed every minute of the time I have put into this 'hobby'. Maybe that helps you understand why I do not mind spending good money on old technology. But I also have modern equipment and cross-check things. (just the techie in me... I gotta do it.) And by the way, my wife and I have been married long enough that she has caught on.... and she knows I need a 'hit' every so often; so she now knows that all the things I buy are not necessary ... but she approves because she understands me.
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Old 07-31-2012, 12:13 AM   #74
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Adding R-22 increases suction temperature???


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Originally Posted by turnermech View Post
any mixture of water and ice will be 32 every drop of water and every inch of ice. this will stay constant until all ice is melted or all water is frozen. This is handy fact of science so mixing should not matter, ice temp will be same as water temp. You would need to let the two adjust to one another several min before testing temp

What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.
I would think that if the temperature in my freezer is -10F, that would be the temperature of the ice until it is warmed up by the tap water I put in the container along with it.
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Old 07-31-2012, 12:35 AM   #75
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Adding R-22 increases suction temperature???


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What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.
Current split (after removing R-22) is 17F

I have checked the gauges - just a few minutes ago:
Suction Line Pressure/Temp: 65psi/40F
Suction Line Temp Measured: 45
Superheat: 5
High Side: 240 PSI
OAT: 88F
Wet-Bulb: 17C/63F

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