Results 1 to 7 of 7

Thread: Attention mf545

  1. #1
    42yrs exp is offline Professional Member BM -bad email address
    Join Date
    May 2003
    Posts
    176
    Only the old timers know. The government and the industry are pushing for higher and higher efficiencies. The problem is that the higher the efficiency the less moisture removal.
    Last year they were pushing 12 SEER. This year they are pushing 13 Seer and above. Every time the SEER is increased the system loses some more of its ability to remove moisture from the air per hour.

    Three years ago I installed a 12 SEER system and immediately noticed that my house did not feel as comfortable at 78 as my 20 year old system,probably a 6 or 8 SEER. An air conditioner not only cools the air it removes moisture, and if the system removes less moisture per hour you will feel less comfortable.

    So, only the old timers know that the higher SEERS suck. The newbees (less than 25 years experience)will say that if the system is design right you will not have any problem, with less moisture removable, bull.


    The SEER on ac systems is like the cars and gas. They keep pushing the envelope for more and more out of these products, and they get more and more BUT AT A PRICE. The price for air conditioning systems and high efficiencies is less moisture removal per hour and less comfort in the home.

    Here is one way to correct for the moisture problem. On my old system I used to keep it at 78F to feel comfortable. On my 12 SEER system I have to keep it at 74 defrees F to get the same comfort feeling. This is a law of thermodynamics and not a manufacturers design problem. So the lower moisture problem on the high SEER units in not due to any specific manufacturer. Every manufacturer will say there systems compensate for the problem. The manufacturers probably will not even consider it a problem.

    Many of my customers have complained about the uncomfortable feeling with the new system. When I tell them to low the temperature 2 to 4 degrees colder, I never hear from them again. And the ones I do say that they feel more comfortable.


    There are those who will say "did you do a heat load calculation, DO you have an engineer design it. Did you do this, did you do that. From my experience 99.99 % of my customers are happy making there home 2 to 4 degrees colder to compensawte for less moisture removal due to high efficience systems.

    I have also experienced this solution (going colder on stat)
    with many customers of other companies.

    Don't make you Air conditioning system installation a nighmare. Many times something simple will solve the problem, but if you get the wrong people involved in solving your problem, you'll have a hellish nigh mare.

    One company came out to a home of a 2 year old system and talked the home owners into a new system. They told the customer they had the wrong system, a lie. They said the system was not designed proberly, a lie. They put a system 20% two large in. The customer was so desperate that they had the 2 yeard old system pulled and a new one put in. The problem was worse with the new system. It was the AC from hell. It was two large for the home. The home always felt damp and muckie. It chilled ya to the bone. Very, very cold and damp.

    well, good luck.










  2. #2
    Join Date
    May 2004
    Posts
    1,462
    You have just made a great argument for variable speed motors. Higher seer is not a problem if you can control the air speed over the coil to control both sensible and latent heat removal.

    PS. My 32 years in the business probably makes me an oldtimer but I stongly believe in properly designed high seer.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  3. #3
    42yrs exp is offline Professional Member BM -bad email address
    Join Date
    May 2003
    Posts
    176

    well spoken

    Well spoken Mr Plain Spoken. The variable speed motor is another answer to the problem. But I live in a poor neighborhood and the people are lucky to have AC let alone a motor that varies it speed relative to load conditions.

    I know, before long they will all be variable speed, and once again the poor will not be able to afford central AC. That's how it started out. In the sixties only those who made big money had central ac systems. The poor, if they were lucky had window units.The cycle of life. Have you noticed that middle class is going the way of the $2 a gallon for gas.

  4. #4
    Join Date
    Jul 2006
    Location
    Ohio
    Posts
    22

    Re: well spoken

    Originally posted by 42yrs exp
    Well spoken Mr Plain Spoken. The variable speed motor is another answer to the problem. But I live in a poor neighborhood and the people are lucky to have AC let alone a motor that varies it speed relative to load conditions.

    I know, before long they will all be variable speed, and once again the poor will not be able to afford central AC. That's how it started out. In the sixties only those who made big money had central ac systems. The poor, if they were lucky had window units.The cycle of life. Have you noticed that middle class is going the way of the $2 a gallon for gas.
    Hi 42yrs exp,

    Thank you so much for taking the time to give such a good and in depth explanation of the high efficiency vs low efficiency systems. I must say, trying to sort through all the information can be a daunting task!

    Yes, we have a high efficiency system--19 SEER--YIKES! Well, we're not happy but we're trying to resolve the whole thing. We switched the fan setting from "on" to "auto" today and this has made a substantial difference in the humidity level and comfort of our home, although the humidity is still higher than we would like. We're trying to work with the company who sold us the system. We have a long standing relationship with them and I'm counting on that as a basis for a happy resolution.

    Again, thank you.

    Michele

  5. #5
    Join Date
    Jul 2006
    Location
    Ohio
    Posts
    22
    Originally posted by plain spoken
    You have just made a great argument for variable speed motors. Higher seer is not a problem if you can control the air speed over the coil to control both sensible and latent heat removal.

    PS. My 32 years in the business probably makes me an oldtimer but I stongly believe in properly designed high seer.
    Hi Plain spoken,

    Our 19 SEER system is a variable speed unit so at least we have that in our favor! We are now trying to determine if the system is oversized. I'm waiting for a call from the service manager and I plan to ask him to recalculate the load (or whatever it is you do to determine the size unit). I'm not sure that was done properly in the first place. I think they may have gone by the size of our old unit.

    Thanks for your input. I really appreciate all the great responses I've received here. I knew so little about the subject and the responses I have gotten have shown me what I need to look for and the questions I should ask my contractor. Thanks again to all who have responded.

    Michele

  6. #6
    42yrs exp is offline Professional Member BM -bad email address
    Join Date
    May 2003
    Posts
    176

    Hummmm mf545

    MF545 - So you have a 19 SEER with a variable speed motor and still have a humidity problem. The highest I have put in is a 13 SEER. So a 19 Seer would have even less moisture removal per hour.

    Did you try to lower the sensible heat setting a few degrees to lower the humidity in the home? Check to see what the setting is on the printed circut board relative to the blower on and off cycle. A shorter run cycle may give you more moisture removal.

    Is the system set to the lowest motor speed on the variable speed motor?

    This may sound silly, but is ever thng in the home closed up so no warm humid air is entering the home. For instance are the kids leaving an outside door open all day. Are there any windows open in any of the bed rooms?

    Do you have a fresh air intake in your system? If so close it and see what happens.

    Just some things you may want to check other than system capacity.

  7. #7
    Join Date
    Jul 2006
    Posts
    1,091
    42yrs said,
    Every time the SEER is increased the system loses some more of its ability to remove moisture from the air per hour.

    Why is that? Low head pressures, high suction?

    You sparked a memory and I had to go look it up. Crawled up into the attic and there it was, my book of old equipment data/spec books.

    I looked up the performance data for an old rheem RPFB 024 with the RHQA810 air handler and a RCPB-024JA

    Who cares about the Mod# it's a 9 SEER... back in the day it was a big deal. Anway, in the regular old data sheet it boasts a 24000 BTU 17600Sen/6400Lat, but in the deeper data... performance data it breaks it down like this

    Using the 67* wb indoor and 95* db outdoor

    920 cfm... total btu 25.4... sen btu 14.7
    800 cfm... total btu 24.7... sen btu 13.7
    680 cfm... total btu 23.7... sen btu 12.8

    I understand the higher (though slight) rise in latent removal at a lower cfm, but why does the equipment deliver more BTUs at high cfm across the indoor coil.

    And by the way, I looked up the data on 10 SEER sensible goes up 100 latent dowm 100.

    Once more, I look at the latent on the newer 10, 11, 12, 13 SEER equipment.

    10 seer 6200 latent
    11 seer 6600
    12 seer 6400
    13 seer 6200

    Oh well, thought I was brain storm'n... it was just a low pressure system.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event