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Ask Yourself "Why"? (25 Posts)
Ask YourselfIn class, I always tell my students to ask themselves why something has happened in order to trace the system back to the initial cause for system failure. Here's a quick example:
You go on an air conditioning service call and the customer is complaining that the system is not cooling the house. You gauge up on the system and determine that the compressor is operating, but the high and low sides pressures are the same. You check the compressor and determine that the valves on the compressor (yes, it's a recip) are leaking. You replace the compressor... Lo and behold, a few weeks later you are back on the job replacing the compressor again... Hmmm... Here's how things could have gone a little better.
You gauge up on the system and determine that the compressor is operating, but the high and low sides pressures are the same. You check the compressor and determine that the valves on the compressor are leaking. Why are the compressor valves leaking? Probably because liquid refrigerant has gotten into the compressor. Why has liquid refrigerant has gotten into the compressor? Because there was liquid in the suction line. Why is there liquid refrigerant in the suction line? Because the evaporator is being overfed. Why is the evaporator being overfed? Because the TXV is fully open. Why is the TXV is fully open? Because the thermal bulb is hanging freely in the return air stream. Why is the thermal bulb hanging in the return airstream? Very likely because the guy who was there had no clue about what is to be done with the thermal bulb on the TXV.
Yes, you will still need to replace the compressor, but in addition to the compressor replacement, you will also have to resecure the thermal bulb.
So, why am I mentioning this to you all? I was down in Orlando Florida for Thanksgiving and stayed at my sister-in-law's house. She asked if I could replace the toilet in her master suite as the water continues to run and keeps her up at night. I told her that the parts in the tank could easily be replaced and that there was no need to replace the entire toilet. She told me that all of the parts in tank have already been replaced twice by two different plumbers and that the problem still persists and she wants the toilet replaced. No problem.
I look at the toilet and notice that the float assembly in the tank is brand new, but the flapper assembly looked like Noah had it on the ark with him. She showed me the paperwork from the two plumbers and they both replaced the float assembly. Wow!
The complaint wast that the water was continuously running so they replaced the float... TWICE!
I was astonished that they simply did not ask themselves why the water was running. How about.... the water is running because water level in the tank is going down. Why is the water level in the tank going down? Because water is leaking out of the tank. Why is water leaking out of the tank? Because the flapper is not making proper seal at the bottom of the tank.
The poor float was just trying to maintain the correct water level in the tank.
So, $12 later the water has stopped flowing and my sister-in-law can sleep!
Hope you all had a great Thanksgiving!EugeneThis post was edited by an admin on December 4, 2013 7:00 PM.
Why is whatI ask myself, why am I not as smart as "The Professor"This post was edited by an admin on January 3, 2014 9:44 AM.
Too FunnyYou are too funny, my friend!Eugene
N/A January 4, 2014 @ 6:33 PM
Because your sisterdropped you on your head face first LOL. I just had to post that
N/A January 4, 2014 @ 6:35 PM
that was fortech-man not you Eugine.This post was edited by an admin on January 4, 2014 6:35 PM.
WoWAir Cond. and PLUMBING!
WHY , unclejohn,just a little bit of plumbing, LOL
LessonI am a firm believer that everything may not happen FOR a reason, but everything happens BECAUSE of a reason. You don't have to know everything to fix everything; just know how to learn and learn how to think.- Joe Starosielec
Guaranteed performance. Guaranteed energy savings.
Serving all of NJ, NYC, Southern NY State, and eastern PA.
David BroomeDavid,How did you know about that? LOL also. ( its true)
JStar, I agree. Way before Professor Silberstein there was a guy by the name of Carl Geist. One of Carls favorite sayings was ,in order to TROUBLESHOOT you have to develop "The Ability to Think". Carl stressed that point a lot in his book "New Ways to Solve Your Refrigeration and Air Conditioning Problems" Copyright 1972 which I bought new. He also made that point in his articles that he wrote for THE NEWS .I miss that guy and his MIND.This post was edited by an admin on January 5, 2014 10:01 AM.
Why Not:As a plumber, I know far too well what you are saying.
So if anyone cares, here's more to add. Regardless of what they tell you about the problem, you need to use your experience skills like looking for the TXV flapping in the breeze.
Take a flashlight and look down the overflow tube. If you see any water moving inside on the bottom, change the flapper. If you take out the flapper, and is shows the marks close to the edge, it has shrunk down from the original size from bleach or things in the water, If you see water "tracks" on the sides of the bowl in the back from the underside of the flushing rim to the water level in the bowl, the flapper is probably leaking. Take some toilet paper and wipe it away. If water appears, change the flapper. Mark the water level in the tank with a pencil and shut of the supply valve. If the level drops, change the flapper. If the water supply is on and it is running over the overflow pipe, repair/change the ballcock.
And the #1 cause of leaking "flappers". THE WRONG ONE FOR THE TOILET FLUSH VALVE! Kohler used to use one basic flush ball for most of their toilets 20 years ago. It was a round ball. Then, they started using a flat one on some toilets that were the same as the ones you could get readily in a hardware store. They all leaked. Then, Kohler started using ones from Fluidmaster. They leaked. And they used one that was a hard plastic with a soft plastic disk. The soft plastic shrunk from chemicals and leaked. Finally, Kohler went back to listing and selling flappers specifically spec'ed for their brand and model of toilets. You can't buy them at HD or Lowe's, only Fluidmasters. That will leak.
Get the right one for your particular application.
Because the same process of reasoning and troubleshooting applies to fixing toilets as it does to fixing your AC problems.
So why does the AC in my 30 YO Condo in Florida have moisture coming around the ceiling grills in some rooms and staining the sheetrock and popcorn ceilings. It didn't do it for 30 years and just started last year. I had a AC Tech here who seemed very knowledgeable. I was concerned because a few years ago, the system stopped working because it was low on refrigerant. A guy came and said that he needed to replace the lines because there must be a leak. It would have been a job running new lines. They go under the slab and would now have to run overhead. He never did the job. I haven't lost any refrigerant. So I told the guy what and why had happened. He put his gauges on the system and said it was OK, slightly low and the temperature Delta T was higher than he liked to see it. It was less than 20 degrees. He added liquid and brought it down to 10 degrees Delta T. Its no different. Typical Florida institutional install. Condenser in a closet with louvered door above the water heater about 4' above the floor. The drain is clean and clear. It makes up lots of water on the coil when it is running in the Summer. Is it just throwing off moisture from the coil into the cold air stream? If so, what can I do about it?
I'm a Heater, not a Cooler. Any suggestions.
icehow about a dirty evap coil, suction would be lo( mimicking lo on Freon)
Coils and other such things:I've thought about that. It drains well, it doesn't look dirty on the underside, I can't see the system side but the air flow seems OK and I get plenty of condensate out the drain. I use quality a quality filter and it never really gets dirty but I change them monthly even so. Maybe there's something to be said for El Cheapo filters that have less restriction and filtering power.
You've given me thoughts. maybe the coil is dirty around the edges and the air only runs through the middle. The flow is accelerated and sucking condensate off the coils into the air stream. I'm waiting for the outside temperature to go down some more before I go up in the attic for a look around. Ann that Flex Duct is above the insulation and in the uncooled, sun heated space.
Thanks for the thoughts to make my aged brain keep working.
Low Suction:The guy didn't think it was really low. It was well within the realm. He wouldn't have done anything. We bought the place in 2005. It was a few years later when the unit was freezing up in the coil and stopped working from a lack of refrigerant. THAT person said that the line set was leaking because he couldn't find any leaks at the compressor or the condenser. I have no idea how often the unit was serviced before that. He seemed to be a "Gypsy Sub Contractor" working for the company that my wife called with a recommendation from a friend. He had his own beater truck with no name on it. He spent as much time on his cell phone as he did on my problem. We gave him permission to replace the line set which would have been one serious job before we went North for the Summer. He never did the job. Three years later, it was still running fine. No leaks. That's why I called the last guy.
I'm sure that you know that it is very hard to troubleshoot something that is working properly.
Lo suctionMorning icesailor, your system is probably Freon r-22 , on a 70-72* day the lo side press should be about 60psig = to 34* Freon temp( evap temp) ,hi side press about 184 psig = to 96* Freon temp ( condensing temp) and no bubbling in the SightGlass/MoistureIndicator. WHAT? No SG/MI !!! Have one put in . Low air flow or lo freon = lower air temp off of evap coil = moisture around supply registers. Can you see the air inlet side of the evap coil? Just because the surface of the evap looks kinda clean doesn't mean the space in between the fins is not dirty. Use a flashlight and a mirror. Can you put a digital thermometer on the suction line( larger of the two) leaving the evap coil? Well insulated of course.This post was edited by an admin on January 9, 2014 3:39 AM.
All pumped up:It's R-22. No sight glass. Why would you put one of those in? They're so expensive. Its like greasing the connections on faucets when you install them. The time it saves you if you ever have to repair it. Another no brainer.
It was a very hot day when he checked it. High 80's I think. It was hot here in Florida this Summer. I didn't question anything he said. He seemed very knowledgeable. I asked him if he was doing anything with gas heat, He replied that he didn't and had no interest in anything like that. I told him that he better get up on it because it was what is coming. So much for that. That the principles are the same
He had two temperature probes. One on the supply and the other on the return. One was his Multi-meter. Both my RMS Multi-meters have temp. probes. I don't know what the numbers were but what I do remember was him saying that the temperature differences were now at a 10 degree differential. In hydronic heating systems I designed, I/we always went for a 20 degree differential.10 degrees usually means that the heat transfer sucks or the flow is too fast. He had 20 degree Delta T before he added liquid, it was 10 degrees after he added liquid. Maybe it was the pressure differential. I'll have to think on that.
But like I said before, I stopped at AC. It is a whole other field. I understand it and I could do it, but I didn't. And at my age, I didn't need to learn another field.
Maybe I need to buy a set of gauges and a good book on the subject so I understand the relationships better. To be honest, it didn't seem to cool as quickly after he added liquid and had the 10 degree Delta T than it did with the 20 degree Delta T. Which would make sense. I probably need to find out the Delta T between the air inlet at the filter and in the outlet as it goes into the system.
Also, the cover inside the outer cover, doesn't seem to fit the same unit. It is painted the same color, but the screw holes don't line up with anything on the frame and there is a notch where there are no pipes for it to fit over. Could I be sucking condensate water around the end of the coil and into the air stream? The bottom of the fan cage has signs of moisture on the bottom over the coils but it isn't rusted. Maybe the quality filters get dirty and cause high suction between the outlet of the filter and the fan. Causing high vacuum and sucking condensate water into the filtered air stream. I wish I had my big Bacharach draft gauge for vacuum readings.
Thanks for the reply. Its given me something to think about. I don't want to replace the unit if I don't have to. I'm not a public money pit.
icesailorI use a SG/MI to save my customers money.You can SEE if the system is low on Freon, you can SEE if there is moisture/ acid in there ,and react and save a compressor. You go to HVACR supply houses? I use mostly SAE ones. An ambient of 90*, the r22 should be about 259.9 psig & 120* in the cond unit, air in 90* air off about 1/2 way. Condensed Freon (liquid) should be cooler than the 120* Freon by 5-10-15-* depending. Evap ,75* room, 55* air off of evap coil,35* Freon in evap=60.7 psig .Out of evap, suction line 35* + 10-12* for SuperHeat( Freon steam) = 45-47*, back at comp another 5-25* depending. Is there a P trap in condensate line at evap? Can you remove drain line and look into line and drain pan?. How many years and the evap coil has never been washed? WHY?WHY NOT?This post was edited by an admin on January 11, 2014 5:22 PM.
Delta T:"" Condensed Freon (liquid) should be cooler than the 120* Freon by 5-10-15-* depending. ""
There's the Delta T and the 10* Delta T. It seems like I remember that the HP was up where you suggest and the low is in the range. When he added liquid, the numbers changed and the temperature changed to the 10* Delta T from 20 * Delta T.
Its a Rheem RCGA 36A2AS17 made/Model # 2/96. The condensate containment seems to be a single plastic pan. All drain openings seem to drain water. I ran a wire up inside and they seem clear. Because the unit is mounted so the flow is vertical, any overflowing of the pan would drip on the filter. There has never been any signs of that.
My condensation problems could go to the crappy Acorn aluminum windows. Living most of my life in New England, I know the muffled sound of tight windows. The sound is so sharp, I often thought a window is open. My explanation/rule of heat loss is that heat flows to cold, and dampness flows to dryness. If it's 100 degrees outside and the humidity is 95%+, and the inside temperature is 80 degrees and the humidity is less than 60% inside, that's a lot of energy trying to get in. Insulation wasn't a priority for the developer. Even though someone in the past added more insulation in the attic space, there is poor ventilation above and the ceiling gets toasty in the afternoon. Sun shining on an outside wall will make it go up.
Adding a Sight Glass requires a vacuum pump and more liquid?
Perhaps my use of quality filters is part of the problem? When we bought the place in 2005, there was that quality universal filter supplied as an OEM filter. It had a "quality" (cheap) filter in it. You know the type, the cheapest one with one pleat per foot. Little to no restriction or filtration. Maybe my obsession with quality filters is part of my problem. I change them every 6 weeks though because I am always doing something that will cause dust.
Thanks for your interest.
I guess I'll have to buy a set of gauges. Being the tool Weenie that I am, I can justify it. You should have seen my lifetime collection of work tools that I had when I left Massachusetts that I wish I had here now. Makes me sick.
You do needan EPA certificate/ license.
EPA Certification/License:I know that. That's why I wouldn't be doing any cutting in and installing any sight glass or any other things that have to do with the system and the refrigerant.
I only wanted to know answers to my questions about the condensation of ceiling registers and the damage to the finish. I called someone recommended. I still have the problem. Not bad in January. Next August? Popcorn ceilings are hard to replace or repair. I'm not trying to second guess anyone. I'm a heater and a plumber. I'm not a cooler. In 2007, I replaced the water heater because I thought it was leaking. It had rust stains on it and every indication I could think of was a leak. Electric's leak. I replaced it. The next year, it was still doing it. The coil was freezing up and when it melted, all the ice melted and ran on top of the water heater, I used to come down at Thanksgiving, and go home, then come back for Christmas and leave after New Year. I would cone back down in April and drive my wife back to Massachusetts. In 2008, when I came down in April, I found that my wife wasn't using the AC because it didn't work. The person recommended by someone sent the "Sub-Contractor" with the beater truck and no name on the side. He said that it was low on gas (which it was) and put more in. It ran fine then. He couldn't find any leaks and said that the line set needed to be replaced. It runs under the slab. I left the next day for Massachusetts and he was supposed to replace the line set. He didn't. After four or five years, I thought I ought to have it checked. Obviously, it wasn't leaking. He replaced a missing cap on a Schrader Valve. The guy had all the equipment and knew how to use it. If he came for an interview, most might not have hired him. Unless they hire Pond Scum. If you can't take a shower before you leave for work, brush your teeth and scrape your face, you don't belong going on service calls and facing the public. Image is important. We bought the place in 2005. It was built in 1982. There were no signs of moisture damage on the ceilings at the few registers that have it now. It didn't have it two years ago. It is recent.
When built in 1982, it had some sort of a AC/Domestic Hot Water coil set-up with a water heater in the closet. The old lines are outside and in the closet, capped off. All 240 of the units had them. All are disconnected. Somewhere after 1996, they replaced the compressor and condenser. It has one of those quality duct board supply plenums going through the closet ceiling with round flex duct in the attic. In a hallway, where the first round take-off is, there was some water damage. I found that there was little insulation around the metal transition and condensation was making up. I double wrapped the connection and it stopped it. AS I think and write now, perhaps the problem is that there isn't enough insulation around the metal transition boots and the hot, moist air condenses on the outside of the metal boots. It is worst on the downstream, outlet side. The insides of the transitions are insulated. I'll have to go up there and look.
Yesterday, I checked the air temperature through the unit. I had 75 Degrees inlet and 55 degrees outlet. 20 Degree Delta T. It's 75* outside and 75 * inside now, Not over 90* and higher like in July and August.
It isn't a Cadillac system. Maybe for Florida, but not where I was from. Maybe for a quickie hack, but I was always under the impression from what little scorched air systems I did that it is always a good idea to have a plenum on the supply and the return. The space in the closet between the top of the water heater and the filter is the plenum. I suppose that the whole closet could be considered a plenum when it is closed off by the doors and all the return air comes through the louvered doors. It works because there's lots of dust on the louvers.
If someone needs to be done in the system, I'll be calling a licensed professional. I'm not one for AC. I consider myself a professional when it comes to plumbing, hot water heat, gas and well piping. Retired now.
Someday, the whole mess will need to be replaced. Not now. My budget doesn't allow for it.
okhaving 75* room temp and 55* out of the supply register is not quiet right, it should be 55* off of the face of the evap coil so the supply out of the register will be a little warmer. This would be a good time to know the comp suction press and the suction line temp leaving the evap and if the liquid line is full entering the evap. The duct should be well insulated, including the top of supply register . A lot of dust on the door louvers suggests dust on the evap coil, no air filter is 100%. Do the louvered doors restrict air flow back into the air handler? Try opening the doors and re-measure the supply air temp.
Air Temps over:I really thank you for your time and interest.
So, the air temperature going into the bottom/filter (over the electric water heater) is 76 degrees, the same as the hallway. The wall electronic clock thermostat is 4' away and reads the same. The air temperature inside the cabinet, just above the A-Coils is 52 to 53 degrees.
The liquid line going into the unit is 79 degrees and the vapor line is 54 to 53 degrees. I'll check the temperatures outside at the compressor in a while when I finish what I am doing as today's project. I'll post back. Guess I'll have to invest in some gauges so I can tell the pressures. I told you that the lines run under the slab for probably 40' so there should be a lot of heat transfer to the ground.
As an aside, we bought the place in 2005 from the original owner from 1982 who lived here year around. She never had a problem. When we bought it, I devised a way to keep the Condo unit dry to stop any mold by wiring in a de-humidistat to run the AC during the summer. It would only run off the de-humidistat. I wired the electric part to act as a heater if the AC super cooled if there was an argument with the controls. It never happened. The maintenance persons lost their minds because they never heard of such a thing. I didn't care how hot the unit got, as long as the humidity was low. It worked well. As I said, we were never here from May to November. I had it set so that the humidity was at 55 % and if the inside temperature went below 60 degrees, it was super cooling and the heat strips would come on. They never did and the electric bills showed it. In 2012-2013, the cleaners futzed with the thermostat-humidistat settings and changed them. Because of a language barrier, the instructions weren't followed by the cleaner and the caretaker lost his mind trying to figure out the concept and the proper settings. I told him to just set the humidistat "off" and set the AC to whatever kept the humidity down according to the temperature on the indoor/outdoor thermometer-humidity meter in the kitchen. I noticed the problem of the peeling ceiling outlets in November of 2013. The electric bills went up.
Time to look for a reasonably priced set of gauges. I always wanted a set but never once had occasion to use them. Now that I can't write it off to my business, I need to buy a set. A lot cheaper than my almost brand new Bacharach Insight combustion analyzer ($1300.00+) that someone offered me $200.00 for. With brand new $300.00 Oxygen sensors installed and calibrated. I gave it to my son.
More: (later)The compressor outside after running for 1/2 hour.
High side-Liquid line: 87 to 89 Degrees
Vapor side: 39-37 Degrees.
It appears hotter and colder a few minutes after starting. The longer it runs, the colder the vapor side gets.
ReadingsThe suction line temp of 37-39 is low, figuring 10-12* for SuperHeat ,then the Freon temp inside the evap coil is 25-27*, if the suction line temp was at the outdoor unit then that's even worse. You need ALL of the temp/press at the same time to make a decision . Indoor air temp of 60* ,then the strip heaters would come on? That's refrigeration, not AC
Strip Heaters:As far as I know, and from my experience after being here for a summer, the strip heaters have never been on. It was only a back up when I didn't know how well the system cooled. It's January 15, it is 67* outside now and is supposed to go to 80* today. If it was 80 degrees in Massachusetts in July, it would be considered as HOT. No matter how hot it got outside, I kept it at 78* to 80* and 85* at night with a clock thermostat. The humidity never went above 60% even though it might be in the 90%'s outside. It just ran longer while cooling.
Years ago, I read an article about using Arma-flex type insulation underground and in wet/damp locations with copper tube. The insulation failed and the copper tube would deteriorate. Ever try repairing copper tube that was stained by Arma-Flex insulation? The line sets run under the slab. The compressor is 16 years or younger by the date of manufacturing and installation. Compressors are probably like water pumps. As they get old, they don't develop the pressures and GPM that they did when new. Perhaps it is getting time for a replacement. I don't relish that. Time for a set of gauges.
Again, thanks for your interest and comments. They are appreciated.
Replacement:Sounds like the thing is getting ready for a dirt nap at the scrap yard. It has a 1996 manufacturing date and could have been installed in 1997 or later. My wife would be here from November until April and I would be North, in comfort, working and sailing. She just doesn't make an issue when the AC stopped working and the house was hot. She doesn't mind the heat, I do. When I came down in April to pick her up in 2008 or 2009, it wasn't working. That was after I changed the water heater because I thought it was leaking and it was the coil iceing up when running and melting when it shut off. I notice the car super cooling and cold air only comes out of one side of the AC. I know it needs a snort of refrigerant. It has happened more than once, I get down and she is driving around with the windows down.
I better get on it while I can still afford it. Before the Wall Street Crime Syndicate and their Bankster Buddies get done cleaning out the rest of my retirement savings to transfer to the 1%'ers. Somehow, I have a vague feeling that those Rheem "Scroll Compressors" might not have worked out so well.