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  1. #1
    Join Date
    Jul 2006


    Hi y'all, newby here. I recently removed a number of trees that were shading my house and now I may have an AC capacity issue. Now during the summer if I set the units below about 80F they will both run nearly continuously. I don't know if it is normal, if my units are old and need attention, or if they are under sized. Anyway here is the data.

    I have a 4200 ft^2 house with two Carrier heat pumps for cooling. The model numbers are 38YH030310 and 38RQ034320. The YH unit runs constantly during the day with a setpoint of 80F. The outside air temp is 95F, pressures are 260 and 55. Air temperature out of the register is 57-60F depending on distance from handler. Return air temp is drawn near the floor and about 77F. The air filter is fairly clean.

    Two questions:
    What is the capacity in tonnage and BTU for each unit and does it appear normal for the one unit to run all day to maintain temperature?

    [Edited by jd990 on 07-16-2006 at 04:09 PM]

  2. #2
    Join Date
    Aug 2002
    Office and warehouse in both Crystal River & New Port Richey ,FL
    The YH is 2.5 ,and the RQ is a light 3.0 ,"nominal" tons.

    Your return at the floor being 77 ,sounds a little odd,do you have the supply grilles in the floor??

    They likely need serving and the coil,and blower cleaned,at least that's a good place to start.

  3. #3
    Join Date
    Jul 2006
    Ok, I have decided to replace both of my 26 year old Carrier heat pump systems with new. So far I have two quotes and another to come the first of next week. In order to compare apples to apples, each quote is for the Carrier Performance and Carrier Infinity sytems.

    The first guy did a basic heat load assessment based on a few square footage measurments, but didn't look at the existing duct work. He wrote out a quote which only specified the system name and tonnage. He admitted that he had been in sales for only three months, but had been an installer for many years.

    The second guy asked a few questions about current system performance and took a good look at the existing duct work and air handler for one of the systems. No heat load calc and not familiar with any duct issues associated with the Infinity system. He emailed a very basic quote similar to first guy.

    Now I am the type that HVAC pros may not like to deal with--engineer in business management--, but I think that there should probably be more to specifying a system than what I have seen so far. So far both have been nice guys, not pushy, and didn't try to BS me, but should I expect more?

    By the way, if any Atlanta area Carrier dealers want to give a quote you can PM me. Go to my profile, click on my home page, email is there. I hope I didn't just violate a rule.

    [Edited by jd990 on 07-23-2006 at 12:16 AM]

  4. #4
    Join Date
    May 2006
    Las Vegas,Nevada
    By moving the trees,you added to the heat gain on the house.Without being there to do a load calc, you might be looking at more tonnage or at the very least a zoning set-up.JMO.26 YO systems have definitely used up their servicable lifetime,though.

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