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Not Cool: Techman & Meplumber:

I really appreciate your input on my situation. I wanted to keep you informed.

I may have other issues with the replaced system. not seeming to work as well as the old, but one thing is that decreasing the heat gain is only a step forward. The attic insulation is a mess. Over the years, different people rooting around for alarm systems and cable TV systems have caused the insulation to be piled up in some places and non existent in others. I know the limitations of IR thermometer guns. But relatively, they show something. If the room is set at 79 in the AM and it is 80 degrees OAT, the inside floor is 75 degrees, and the ceilings are all 79+/- and one room is 78degrees, it gives you a guideline. But in the room that is 78*, there is a closet with an access panel in the ceiling with no insulation, and the side facing in measures 101 degrees, it is a good indicator that there is little resistance to heat gain in that area. I know that the area above this closet has had all the insulation pushed away and not put back. I'm going to have additional insulation blown in.

The issue I discovered should be of interest to you. My theory that adding additional attic ventilation (full length ridge vents) 3 years ago has added to the problem by increasing the humid airflow in the attic increases heat gain that is putting additional load on the system. I have three recessed ceiling lights in the ceilings. The three incandescent bulbs add heat to the building. They aren't IFC so they can't be covered with insulation because the air is part of the cooling part of the listing. So, I changed them to LED spots and dimmers and I will do something to cover them up so the insulation isn't in direct contact with the housing. The worst that can happen is that they might blink off and on if they get too hot. They are only 12 watt LED bulbs though. But when I stuck my hand inside to guide the new bulbs in to the sockets, I was surprised to feel how much humidity/moisture I could feel in the top of the housing. It was extremely noticeable.  I suggested that the moisture was traveling through the insulation and through the gypsum ceiling, where it was being absorbed by the cooler and dryer air. It never goes above 50% inside while yesterday, it was in the 80% range outside. The only place I get any condensation is on the closest and coldest metal ceiling registers. And the condensation shows up first on the ceiling, where the register meets the sheetrock and comes from under the grill. Yesterday, during the hottest part of the day, the structure gained 1 degree (78* to 79*) and the humidity outside went to over 80%. But the humidity inside stayed below 50%. The closet room with the access, the surface temperature went from 101* to 106*.

In my life as a Hydronic Heater, I found a lot of problems with cold air infiltration in recess ceiling lights. Enough so that in a well and properly ventilated unconditioned space that had recessed ceiling lights, you could have a 28 degree OAT day with 35+ MPH wind and not be able to get the room to a temperature above 60 degrees and the boiler is off on high limit. Go back on another day and the OAT is 10 degrees, the same room is 70 degrees inside and the boiler is cycling. On the cold, windy 28 * day, inside the light is 34 degrees inside the light housing. On the 10* day, it is warmer, maybe 45 degrees inside the light housing. It doesn't matter if they are IFC rated or not. They still leak/infiltrate air. If you ever have a lack of cooling call, and there are recessed ceiling lights, especially in cathedral ceilings, look there. I promise you it will be surprising to you how much is lost there.

Additionally, the AH has some EEV Motorized valve assembly that controls liquid going in to the expansion valve. It stopped working and the system stopped. It must be a "Normally Open" valve because when they by-passed it, it became fully opened and the vapor return line is now very cold and at the compressor, it is now sweating when it is running. That should qualify for something. I don't think it was ever working properly. I never saw the condenser sweat since it was installed. It does now. Like the one beside it.

I felt that it was extremely restricted in the return airflow. I have always used quality air filters. I change them once a month and I can see the dirt on the air side. If the AH is running when I take off a filter, it will try to suck it back. When I try to put it back, it sucks it right out of my hand. The louvered cover they send to use in place of a bottom inlet will do the same. It adds a lot of restriction to the intake. That's why I want to cut out the louvers. The other day, the inside temperature started to go up while running. I took off the filter and louvered panel. Air flow improved. If the bi-fold louvered door is not quite closed, the intake return fan will suck it closed. The better the filter, the more restriction it can add. I figured that out. Cheap filters have a place.

If you have done any small boat single handed sailboat racing like I have for most of my life, you appreciate the value of good, clean and undisturbed air.  It would have been better to use the bottom return because there is less turbulence in the air going through the louvers than when it is only a few inches from the intake.filters. Its what makes airplanes fly and sailboats sail.


  • Techman
    Techman Member Posts: 2,144
    Not cool

    Happy to be of help, Dan's idea of knowledge sharing at work.

    This is where knowing what the system freon pressurers were would have cleared up this problem sooner. For your own sake and understanding of AC , try to get an actual press reading . The loside press would have been low for a given set of conditions.
  • icesailor
    icesailor Member Posts: 7,265
    Under Pressure:

    Understand that I am not the cooling pro. Someone else is. Those gauges. Who'd a thunk that you could tell the temperature with a set of Magic FM gauges? Pure Magic.

    There are only two types of issues with troubleshooting.

    #1 If it is new and it doesn't work, "Why doesn't it work. What do I need to do to make it work.

    #2 It worked for 20 years. Now it seems to be working, but isn't. What changed?

    What needs to be corrected to make it work.

    Its all based around Mr. Watt and his steam engine. AC systems are just Steam Engines with a different medium, running in reverse. Both depend on Phase Changes. If you have a 100 year old steam system that worked well for 95 years, and it suddenly started to sound like the chain gang was in your house turning big ones into little ones, you can look around for all the bad steam traps and un-pitched radiators in the world. But if someone did an asbestos remediation 5 years ago and they didn't recover the steam pipes, you might be letting the chain gang loose inside those big old pipes. You want the phase change inside the pipes or inside the radiators? Insulate the pipes with lots of insulation and FM can occur. The insulation removal also cut down on the output of the system. "Heaters" usually understand all that. But "Coolers", due to the nature of life, don't always know or understand what they are dealing with.

    Where I lived and worked in Massachusetts, environmental conditions are extreme. In the old IBR H-22 heat loss guide, there were two places that they considered to be and use 0 (Zero) degrees OAT, but Boston was higher (+05* and Pittsfield was -2*. Where I lived wasn't colder, but the wind blew all winter at well above the wind infiltration factor figured into the constant. It never went to "0*". Maybe 10+". I remember pulling my arm out of a broken meter pit and having ice form on my arm after I pulled it out. Blowing 40 MPH. So, we dealt with a 70 degree differential and always went with the size boiler over the design load. The new IBR/GAMA H-22 Heat Loss Guide no longer lists those same two places. Nor does ACCA or ASHRA. Someone though that high wind air infiltration was an insignificant issue. I assure you that it is NOT. But they're smart, and I'm not. They didn't ever ask me of MY opinion.

    So, here I am in Florida. ACCA says that you or I should use 90 degrees OAT as the factor for my area with a moderate swing and size it so it will maintain 75 degrees inside. I've already had well over 10 days over 95 degrees in my area. Last Summer, I had at least 10 days at over 100. I've had 100+ degree days this year already. With "global warming", it's not going to get cooler. Los Angeles, CA and Wilmington, NC are on the same latitude. But Los Angeles has a lower high degree design factor than Wilmington. Growing up in LA, I remember lots of over 100 degree days in September. Does the factor need to be bumped up? What a political ship show that would be. I've never been to Wilmington NC. I thought Wilmington was in Delaware.

    From personal experience, I know that who did my work was more than competent and knew his craft well. Its the craft of others that are weak. If something worked for 30 years and then it doesn't work well under extreme conditions, why? There are 240 units in this 30+ YO development. Less than half are the size of mine that is the larger size. They all have 3 ton units and I am an end unit with a greater loss. I'm closer to the design maximum than most of the other units. And maybe all the end units are the bigger ones. So the smaller ones are over sized compared to me. If I started to complain that the new system didn't work like the old one, why?

    In the competitive world of today, a lot of potential customers only care about price. $50.00 will give the job to a hack. $1,000 will be sure to give it to the hack, even if the customer knows the hack is a hack and is known to do a bad job. When they replaced the compressor and replaced the pad, the Jamaican dug up the old line in the back and found a kink in the suction line. I didn't see any reason for him to have dug it up. But he did, and replaced the line and eliminated 3 couplings. Quality work. In February. If I knew nothing about heat loss/gain. I'd think they did a bad job because now it has issues. If it was just my wife, you wouldn't want to be dealing with her. In passing last night she commented that "WE" sure have learned a lot about AC haven't we? We sure have. Understanding what you are dealing with is key. Give people choices. If they might need a bigger system, but need additional insulation, tell them. Just don't have some estimator spend 5 minutes looking at a replacement. You might miss something.

    In my experience and opinion.
  • meplumber
    meplumber Member Posts: 678
    Not Cool

    Sorry for the delay, we have been pulling 14+ hour days trying to punch out on a project.  My service guys and I have a massive amount of equipment on this project (boilers, RTU's, a MultiStax chiller, and more air handlers than I can count) to startup and commission.

    Ice, I am not sure that I helped that much, but it looks like you are learning more in a few days of tinkering with your system than some of my apprentices have in years.  As Tech said, the first thing that I would have done was throw the gauges on.  The low suction would  have indicated the low airflow and hence a high delta across the coil.  You are on the right track.

    Good Luck.
  • icesailor
    icesailor Member Posts: 7,265
    Low Flow-High Gain:

    I understand about the time and the work. Some don't care what time you leave for work in the morning (as long as you don't wake them up) and insist that we be home by 6:00 PM for dinner (and don't be late) and don't work weekends. Where do the extra goodies come from?

    As far as restricted/low flow ducting, I understand how restricted flow would show on gauges because its the same as having a too small radiator on your car and pulling a heavy load. A compressor and a car engine are just heat engines. The radiator is just the means of removing wanted or unwanted heat energy, heating or cooling. Like steam (AC is just a steam boiler in reverse), whatever the pressure is, determines the temperature of the water before it flashes into steam. (Square Root of the water pressure X 14 +198 equals the boiling point of water).

    You take the high side pressure, and then you know what the temperature of the liquid turning to vapor like the steam. The return vapor is also under pressure but it is colder and under less pressure. The temperature pressure differential is the amount of heat energy used to remove/transfer heat energy from one side of the coil to the other (inside). I still think that my #1 issue is excessive heat gain through the ceilings. That I also gain humidity through the ceiling because of a lack of a vapor barrier in the vinyl ceiling paint. The structure always maintains 50% or less humidity, no matter how long or less it runs. Yesterday, I found that I have many places where people have gone where there is less than 2" of attic insulation and other places where it is bare.

    This all started because my energy bills went UP after the install. I dealt with it until the unit stopped working. It has some kind of electronic expansion and evaporative control system. Something went wrong with that. All run by a FM Board. Its supposed to create magic tricks. To me, it looks like a potential PITA board. It has a gas temperature sensor (GT) which I guess is the liquid temperature and a Evaporative Temperature Sensor (ET) that appears to come out AFTER the distribution fitting. That control runs an electric motor that controls the rate of liquid flow. I don't think it ever worked properly from the beginning. Its a Normally Open motorized valve, and the FM board tells it how much to be open or closed. If either of the two sensors (GT & ET) migrate to do Magic Tricks, the pooch is screwed. One of those two sensors told the FM board to shut down the EEV stepper motor. Disconnected, the valve is open, and the vapor line is cold like it has never been before.

    I think that the design of the high tech AH leaves something to be desired. Designed by the same people that designed the camel when they were trying to improve the horse. You can't push the same amount of air through a 16" x 16" opening that you can through a 16" X 20" opening without increasing the fan speed, And make it noisier.

    Its like my wife says. "You can have anything you want. Just not everything you want". Same with knowledge. If its important, we'd know about it. Like a 3 ton AH with a 16"X16" outlet. Replacing a AH that has been replaced before, so you have a X2 hacked supply plenum that need to be replaced. You should be able to use the same size as the new AH. And if you called them with questions about problems, they are like little kids that ate the Blueberry Pie. "NOOOO, Not US mommy". With blueberry pie all over their faces.

    The other thing my wife says: "When I need help, I call me".