Page 1 of 2 12 LastLast
Results 1 to 13 of 14
  1. #1
    Join Date
    Jul 2005
    Posts
    14
    I'm not happy with the performance of my Carrier 2 speed top-of-the line a/c. I'm convinced the unit was not sized correctly. I have a 3 ton. My understanding was that the unit would have long run times on low and kick into high on extremely warm days. The problem is that I hardly ever see the unit run on low. It usually runs on high even when the outside temp is less than 78 and the set temp is 73. The result is an uncomfortablly low RH.

    Tech came, never seen a 2 stage a/c, (did/t even believe me when I told him I had one). Says everything checks out but wanted to replace the Infinity T-Stat. Again, because he has never seen one, let alone understand it, he expects it to act like a "traditional single stage a/c and thermostat" ie. set temp 73, a/c kick on at 74 , turn off at 72. I had to explain to him how the thing works. Anyway, I did'nt allow him to change it because I have no confidence in his ability to hook it up correctly and as far as I'm concerned, it works fine.

    I don't think a proper heat load calc was done, taking into account our very unique floor plan (raised bungalow, raised by full story), 2 story foyer (heat trap) and our many oversized windows.

    How do I get an independant heat load calc performed? Are my expectations out of wack. Is 77 degrees considered extremely warm?

    Also have a question re High Cool latch. Set it to 90 to keep unit running on low. Maintained a comfortable RH of 46 and temp 73 so I thought problem fixed. But as the temp started to rise today, unit still kicked into high when outside temp reached 77? Shoud'nt the high cool latch prevent this?

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Th elatch can be overidden if it can't maintain the temperature.

    Sounds like something is wrong ,not sure what.


    Load calculation can be done on this site at the 'bullseye " above for a small fee.


    I'd call them back ,and request a tech with some training on Infinity.



    New construction,or what size did you have before?

  3. #3
    Join Date
    Jul 2005
    Posts
    14
    The house is about 18 years old. We purchased the home about 3 years ago. The a/c unit that we replaced was an Amana and no tech here (Toronto) could tell what size it was. However, it ran 24/7 and could not get below 78. We were using more than 7000 KWH's per month thus the decision to upgrade to an energy efficient unit.

    When the Carrier was installed last summer (not a particularly hot one), I thought the unit was running on High way too much but thought the problem was our roof, which had inadequate venting. Roof now replaced with add'l vents. House, when a/c is not required, is cooler than it was before. A/C however runs on high and never really cycles. Currently, the outdoor temp is 73, set temp is 73, and a/c has been running on high for nearly 2 hours.

    Windows are double glazed but leaky. Triple glazed, Krypton filled, double Low E to be installed later this month.

  4. #4
    Join Date
    Aug 2005
    Location
    PA
    Posts
    104
    So how does it work now since you should have new windows?

  5. #5
    Join Date
    Jul 2005
    Posts
    14
    The windows are amazing and have certainly reduced the cooling load. Before, it was uncomfortable to enter some of the rooms when the sun was shining in. Now, you are comfortable right up close to the windows with the morning sun beating in. No window treatments required (other than for privacy)! A/C has responded favourably. Next home improvement is the attic insulation and the rest of the windows to reduce the cooling load further.

    By the way, I just received my hydro bill for the 62 day period ending July 27th which was prior the change of windows. I compared my usage to the same period 2 years ago prior to making the furnace and a/c change. Even though this has been a record breaking year in terms of heat, my total usage decreased from 5617 KWH to 3451 KWH!!That kind of performance should put the skeptics in their place! (previous post mistated the KWH's used prior to the change out).

    As stated before the a/c is running better than before,however it still struggles after the sun has gone down. I figure it is dealing with heat built up in athe attic which is penetrating my ceilings?? I figure if I do some sealing up there and improve the insulation, I should see a big difference.





  6. #6
    Join Date
    Aug 2004
    Location
    Great White North
    Posts
    92
    Bolsen: Is it possible that you told the installer/supplier that you would be putting in new, triple glazed windows, attic insulation, etc? If you did, then perhaps he did the load calcs based on your "future" improvements. That way, your system wouldn't be too big once you did the fix-ups.

  7. #7
    Join Date
    Jun 2004
    Posts
    146
    Originally posted by bolsen
    By the way, I just received my hydro bill for the 62 day period ending July 27th which was prior the change of windows. I compared my usage to the same period 2 years ago prior to making the furnace and a/c change. Even though this has been a record breaking year in terms of heat, my total usage decreased from 5617 KWH to 3451 KWH!!That kind of performance should put the skeptics in their place! (previous post mistated the KWH's used prior to the change out).
    What a difference expectations make. I'm in the Seattle area where the summers I believe are similar to Toronto's. I have a 4 ton heat pump. My 62 day electric bill ending Jul 26 totaled 1809 KWH (~29 KWH/day). I'd be screaming if my 2-month electric usage was 3451 KWH let alone 5617 KWH. What's your electric usage during the non-cooling months? Somethings using a lot of electricity - maybe your AC, but maybe something else.

  8. #8
    Join Date
    Jul 2005
    Posts
    14
    To garry b

    No, those quoting assumed my existing windows and never in quired about changes. I had expressed concern about the a/c being undersized due to the heat load from the above-average amount of glass area and the 2 story foyer. I was told that as long as the windows were double-glazed,which they were, they were not an issue. My decision to make these upgrades were because of high gas and hydro consumption.

    To go redskins

    I am jealous of your hydro numbers. My record consumption was 5855 KWH for a 62 day period so you can understand why I would be thrilled with my new numbers. We do have a pool. We have started to shut the pump off for about 10 hrs a day to no ill effect to the water condition.

    Since making the furnace change, we have obtained a record low of 1756 KWH (which is almost what you used for a cooling period) during a non-cooling, non-swimming pool 58 day period ending Mar 26, 05.

    I agree that our hydro consumption is high but I don't know what else I can do. Our appliances are all less than 5 years old. My husband has changed every lightbulb to those new energy efficient kind. We have a gas dryer as well as a gas hot water tank.

    Any suggestions as to how I might figure out what is using so much hydro?



  9. #9
    Join Date
    Jun 2004
    Posts
    146
    My low point in recent years was about 1450 KWH for a 2 month billing cycle. So that's not really that different.

    Unless you've got some other big electrical appliance that you only use during the summer, then the AC is probably the most likely culprit.

    The way I checked mine was to use an ammeter to check its typical electric usage and then put a timer on the thermostat to see how long the AC is running per day.

    Below is a snapshot of my ammeter measuring the current.



    It's showing 12.93 amps. It varies depending on temperature, but my unit is usually between 12 and 13 amps. I also measured the voltage at 235 volts. So with that I can measure the approximate power usage to be 2820 to 3055 watts per hour. So it's using about 3 kilowatts per hour.

    Below is the timer (Omron H7ETNFV1B) I attached to my thermostat. This is a cheap timer I bought for about $16. It's wired to the C and Y terminals on the thermostat to measure the run-time of the AC (or heat pump in my case). The second one off to the left is used to measure the heat strip usage during the winter.



    So with this I've been able to keep track of my AC usage. I averaged about 2.25 hours/day in July and about 3.2 hours/day so far in August. That a little less than 7 KWH/day in July and almost 10 KWH/day in August for AC.

  10. #10
    Join Date
    Jul 2002
    Location
    37760
    Posts
    420
    Anyone checked to see if the piston was accidentally left in the coil when the txv was installed and or subcooled to manufacturer specs?

  11. #11
    Join Date
    Mar 2004
    Posts
    1,042
    Where is all the hydro going?

    The size and power consumption of your pool's pump may vary, but for an example, my condo association has a small pool. I have determined the power consumption of it, running the pump 24 hours a day (required by local health codes for public pools), is about 1800 kwh per month. That's JUST the pool.

    You may want to investigate cutting back further on your pump's running time. You may also have a time-of-use metering plan available from your utility that will give you a discounted rate for running the pump when load on the grid is low. There are also demand-based plans in some areas that will give you a lower rate if your consumption is steadier than average (as it tends to be when you burn up lots of power because you run a pool pump for hours and hours every day).

    Since you can only get down to 1800 kwh when not running the pool's pump at all (as I understand what you said), there may be some other energy hog present and unaccounted for. You might want to look around in your circuit breaker panel for any circuits you'd never really considered that might be there. You may have electric heaters in your roof to prevent ice dams, for one. If need be, you can (or you can have an electrician do it) use a clip-on amp meter on the circuits at the breaker panel to see how much power is going into each circuit; that will help you figure out where the energy hog is hiding.

    Do you have an HRV, ERV, or steam humidifier, by chance?

  12. #12
    Join Date
    Jul 2004
    Posts
    253
    I have a Bryant 2-speed system - same thing that you have - Bryant is the same as Carrier. For the last 3 months, I have averaged 9.6 hours a day on low-speed and 3.6 hours a day on high-speed for a total of 13 hours a day. I live in southeast Georgia.

    Originally posted by bolsen
    I'm not happy with the performance of my Carrier 2 speed top-of-the line a/c. I'm convinced the unit was not sized correctly. I have a 3 ton. My understanding was that the unit would have long run times on low and kick into high on extremely warm days. The problem is that I hardly ever see the unit run on low. It usually runs on high even when the outside temp is less than 78 and the set temp is 73. The result is an uncomfortablly low RH.

    Tech came, never seen a 2 stage a/c, (did/t even believe me when I told him I had one). Says everything checks out but wanted to replace the Infinity T-Stat. Again, because he has never seen one, let alone understand it, he expects it to act like a "traditional single stage a/c and thermostat" ie. set temp 73, a/c kick on at 74 , turn off at 72. I had to explain to him how the thing works. Anyway, I did'nt allow him to change it because I have no confidence in his ability to hook it up correctly and as far as I'm concerned, it works fine.

    I don't think a proper heat load calc was done, taking into account our very unique floor plan (raised bungalow, raised by full story), 2 story foyer (heat trap) and our many oversized windows.

    How do I get an independant heat load calc performed? Are my expectations out of wack. Is 77 degrees considered extremely warm?

    Also have a question re High Cool latch. Set it to 90 to keep unit running on low. Maintained a comfortable RH of 46 and temp 73 so I thought problem fixed. But as the temp started to rise today, unit still kicked into high when outside temp reached 77? Shoud'nt the high cool latch prevent this?

  13. #13
    Join Date
    Feb 2002
    Location
    Toledo,OH
    Posts
    142
    Please tell me you are using a 58MVP and why arent you using the infinity control stat. Your system probably aint designed for 2 stage. Must have variable speed blower with this condensor.

Page 1 of 2 12 LastLast

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