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  1. #27
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,879
    My comments:

    1. Efficiency has nothing to do with how long the unit runs. Your 25 year old system had a low seer and your new one 10 seer plus.

    2. Set the thermostat and forget it (was also good advice from another poster) IF you want to screw with the thermostat get a programmable one and set back a few degrees.

    3. A properly sized system will not pull down temperature very fast on the hottest day. Qac - Qload = "thermal mass" X dT/dt At the hottest part of the year the capacity of the ac just meets the load therfore it won't be moving temperature all that quick. "set it and forget it" you wont save any money by shutting off the unit because when you turn it back on not only are you cooling the temperature of the air in the house but you also have to remove the heat on the "thermal mass" or in other words the heat contained in the building envelope and all the contents.

    4. Did you go with the lowest bidder? If you did then dont' be surprized if they dont have a micron guage and dont pull a vacuum but purge the system. Get the system tuned by a reputable company to check the charge.
    Give a man a fish, he will eat for a day. Teach a man to fish, he will eat for a lifetime.

    Give a man a capacitor, doesn't know what to do. Teach a man to install it, now he knows everything.

  2. #28
    Join Date
    Jun 2006
    Posts
    628
    How far up in the bids need one go to get basic competency? Somehow I think incompetence is available at a wide range of prices.

    OP wasn't too clear about it, but it sounded like he said he left the system on with 75F set point for 27 hours and the system could not keep up as temperatures went up the second day.

    Model numbers would be nice for this exercise.

    What can the guy do though, the AC is in, and its too small, or not working well. Maybe the thing to do is verify its working properly first.

  3. #29
    Because all the problems and concerns, I am not comfortable running the system. I only run it on very hot days (twice so far), therefore it's not possible to look at the bills to determine the efficiency. Plus, PSE&G does not always provide actually reading every months.

    Originally posted by thomefan2579
    youll probloy be surprised when you get your gas bill the system sounds like it runs like mine and is very effeicnt i set it for 70 all the time and have very low bills

  4. #30
    1. Condenser - Trane XB13, 2-ton, 13 SEER
    2. Evaporator Coil - ADP TE32436, 1.5-3 ton (www.adpnow.com)

    No check of ductwork, they already exist for 25 years.

    Yes, it's in an attic.

    I live in central New Jersey.

    Originally posted by HVAC/Stud
    What is the brand and model #?

    Is the evap coil and condenser unit an ARI match?

    What seer is the unit?

    Was any check of the duct work done?

    Is the duct work in an attic?

    Where do you live?

    STUD

  5. #31
    Started the system at 6:45PM outdoor temp 85F, indoor temp 86F.

    around 7:15PM
    outdoor temp 85F, indoor temp 85F
    closest outlet air temp: 71F
    farthest outlet air temp: 72F

    around 7:45PM
    outdoor temp 84F, indoor temp 84F
    closest outlet air temp: 70F
    farthest outlet air temp: 71F

    around 8:15PM
    outdoor temp 84F, indoor temp 83F
    closest outlet air temp: 69F
    farthest outlet air temp: 70F

    around 8:45PM
    outdoor temp 83F, indoor temp 82F
    closest outlet air temp: 68F
    farthest outlet air temp: 69F

    I also measure the inlet air temp, it says 82F. I was a little puzzled why it has the same reading as thermostat. But I think of two possible explanations:
    1. the thermostat is 6 ft up on the wall, but the inlet is close to the floor.
    2. The reading comes from the two thermometers, and they may not agree exactly.

    Before I shut down my system, I went out to balcony and put my hand over the condenser fan, the temperature of the air blowed out seems very close to air temperature. It seems to me that the cooling system is not very good at taking the heat out of my house.

    Around 9:15PM, since the outdoor temp is the same as indoor temp, we shut down the system, opened all windows and just used fans instead.

    This is a cooler day compared to the last run, and the result is very similar too.

    Any insights?

    Originally posted by mayguy
    so what is the temp reading you've gotten?

  6. #32
    you are in some trouble why by the xb line the xr line is like 200 more and has double the warranty something sounds fishy this was the lowest bid correct and only 5 year compressor and coil warranty shoulda got the xr13 properly installed its also much quiter

  7. #33
    also can you get a temp on the return near the furnace and one just above the a coil so we can get a temp drop if your 18-20 degrees its working pretty dang good

  8. #34
    You are right, this is the lowest bid. But I think the problem is not what kind of equipment you selected, but how the installation is done.

    Originally posted by thomefan2579
    you are in some trouble why by the xb line the xr line is like 200 more and has double the warranty something sounds fishy this was the lowest bid correct and only 5 year compressor and coil warranty shoulda got the xr13 properly installed its also much quiter

  9. #35
    The inlet is less than one foot to the furnace, so the temp should be the same. However, I am not able to measure the temp just above the coil because it's closed.

    Any suggestion to get a ballpark estimate? The closest outlet is about 9 ft from the coil and I measured the temp as in my previous post (72 ~ 68 F).

    Since the temperature drop between closest and farthest outlet is about 1F, we can assume the temp just above the coil to be in 71 ~ 67 range. The inlet temp is in 86 ~ 82 range. The difference in average is about 15 F. Not very good at all.

    However, there is one difference between testing condition and normal usage. Under normal usage, I will close the close outlet because it's almost right above the inlet. The cool air comes out and goes right back in the system. It's not a good design actually. I will measure the temp drop under that condition next time. But I would expect the difference to be small.

    Originally posted by thomefan2579
    also can you get a temp on the return near the furnace and one just above the a coil so we can get a temp drop if your 18-20 degrees its working pretty dang good

  10. #36
    Join Date
    Jun 2006
    Posts
    3
    You have given a lot of information but I am a little confused with the results you stated after setting the thermostat at 75 and levaing it for 27? hours.

    You said: I do understand the difference between efficiency and capacity. And neither of them hold up to my expectation. I set target temp to 75F and kept the system running for 27.5 hours (2:30PM to 5:00PM the next day). It took 10 hours to get to the target running continuously, while the outdoor temp has dropped from 91F to 76F. But it can not hold that temperature the following day starting from 10:00AM, it started running continuously again. The on/off cycles only happened between mid-night and 10:00AM. I think it's very inefficient, only marginally improved compared to my 25-yr old system.

    My question is how high does the temperature go if you just let the system run? It's not really clear in your answer here.



  11. #37
    The following day is 1 ~ 2 degree cooler on average and the cooling system can only maintain 76F when the outdoor temp is mostly at eighty something degree (hit 90 for 1~2 hour max).

    The most problem here is that it ran non-stop. During on/off cycles, the indoor temp will hit 76 and system turned on, but it will cool back down to 75 and then system turned off.

    Originally posted by cme4oil
    You have given a lot of information but I am a little confused with the results you stated after setting the thermostat at 75 and levaing it for 27? hours.

    You said: I do understand the difference between efficiency and capacity. And neither of them hold up to my expectation. I set target temp to 75F and kept the system running for 27.5 hours (2:30PM to 5:00PM the next day). It took 10 hours to get to the target running continuously, while the outdoor temp has dropped from 91F to 76F. But it can not hold that temperature the following day starting from 10:00AM, it started running continuously again. The on/off cycles only happened between mid-night and 10:00AM. I think it's very inefficient, only marginally improved compared to my 25-yr old system.

    My question is how high does the temperature go if you just let the system run? It's not really clear in your answer here.



  12. #38
    tiger 15 is not great but not horrible i have not done a split on mine either try this set it at 75 and leave it there turn it on in the am and let it go let us know if it stays there or not maybe even try 70 i just check my temp from return to vent and it was 16 and my house stays at 70 no matter what temp it is outside but i let mine run 24/7 i would try that and see what happens if it can pull a house down to 70 and hold it in 90 heat your fine. my system runs alot as well highest bill last summer was 75 bucks and it was a hot summer here in ohio

  13. #39
    Thanks for your advice, I have run the system on a not very hot day by setting target temp to 75F, it ran 19~20 hours on 24 hours basis, and it could not stay at 75F.

    I think the most important thing is whether skipping those important steps during installation is acceptable, and what kind of short-run and long-run problems are typcially anticipated. And how do I go about to dispute the problem and have a solution for it.

    In the worst case scenario, I would have to find another contractor to fix the problem. I suppose our professional members here can provide a lot of insights how to remedy the system.

    Originally posted by thomefan2579
    tiger 15 is not great but not horrible i have not done a split on mine either try this set it at 75 and leave it there turn it on in the am and let it go let us know if it stays there or not maybe even try 70 i just check my temp from return to vent and it was 16 and my house stays at 70 no matter what temp it is outside but i let mine run 24/7 i would try that and see what happens if it can pull a house down to 70 and hold it in 90 heat your fine. my system runs alot as well highest bill last summer was 75 bucks and it was a hot summer here in ohio

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