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High Humidity w/new compressor

Hoping someone can help...old compressor dies a few weeks ago, and we had a new one installed. It's a Spacepak system, the air handler is a 4860, and the old compressor was a 5-ton. My a/c guy did some calculations and suggested the 5-ton was a bit oversized for the 2,600 sq ft we have, and suggested we switch to a 4-ton to avoid it running for too short of a period. Last 3 days has hit 95+ degrees and high humidity, and the humidity in the house syrocketed (over 60%), and then slowly comes back down into the 40's at night.



I've contacted my guy, but of course by the time the heating/ac guy comes back out tomorrow it will be cool outside, so I'm trying to figure out what could make everything go so haywire. In theory, the new unit should be running MORE often, and take out more humidity than before. I'm going to look for drainage issues, but any other ideas on how going from a 5-ton to a 4-ton could make everything go so haywire in what's a pretty small home? Did this guy screw me over by switching to a 4-ton?

Comments

  • RDSTEAM
    RDSTEAM Member Posts: 134
    ???

    hard to say without seeing the house. thats a pretty large house and depending on alot of variables it could go either way. usually with a smaller condensing unit and a larger evaporator you will get more dehumidification not the other way around. however, spacepak is a high velocity system so the air isnt in contact with the coil for very long and your doing more sensible heat removal than latent. I'm not to sure if you can adjust the fan speed on the handler. sounds like your cooling down temp much faster than removing humidity.
  • RDSTEAM
    RDSTEAM Member Posts: 134
    did he

    put in a condenser that space pak uses with their systems?
  • RDSTEAM
    RDSTEAM Member Posts: 134
    did he

    put in a condenser that space pak uses with their systems?
  • Techman
    Techman Member Posts: 2,144
    Hi-Veloicity systems

    operate with the evap coil temp very close to freezing,giving good dehumidification.By switching to the 4t comp the evap temp is higher,giving higher humidity .As a mechanic I try my best for my customers. Not knowing something ,BUT!!!!!!!! trying to do good w/ lousy results ,does not necesserily mean you are being taken advantage of . How this is handled will determine if your mechanic is a good guy to keep  or not .My customers give me A LOT OF LATITUDE,{which means I'm not sure often enough]. 
  • rickrox
    rickrox Member Posts: 2
    Found the culprit

    Well, I'm no AC expert, but I starting tracing it down yesterday. Looks like it was overcharged (his thinking, not mine).



    I left work early, and arrived home to nearly 100 degree outdoor temp. The fan was blowing on the outdoor unit, but the compressor was not running. I shut everything down, checked the attic (air handler) and when I switched everything on the compressor kicked in. Ice-cold air...for about 5 minutes. Sure enough, the compressor tripped off again.



    Now it's 60 degrees outside, so everything works fine, but he just came out to bleed off some charge, and said he'll be back to check it on a high-heat day again as well. He thinks the house remained somewhat cool, but humid (it never got over 78 degree inside) because it kept tripping on and off for the full 3 days, running for 5-10 mins, and then tripping off for longer periods.



    Guess I'll have to wait for a really hot day again to see if the 4-ton is up to the task.
  • RDSTEAM
    RDSTEAM Member Posts: 134
    edited June 2011
    the unit shouldn't be

    going off after 5 minutes. that just means its being overworked for a specific reason. we can pretty much eliminate the fact the its going off on high head because of a dirty coil since its new. you may have non-condensables (air, water or some other form of contamination) or your overload is going off.
  • John Mills_5
    John Mills_5 Member Posts: 935
    Hmmmmmm

    Why is he bleeding off refrigerant? Which also begs the question ... where did the refrigerant go? Hopefully into a recovery jug. But 60 ambient is too low to be messing with the refrigerant level anyway.



    First question is to figure out why the unit is quitting after 5 minutes. Could be a high pressure switch in the outdoor unit causing it. What brand of outdoor unit?



    Could be the freezestat on the coil causing it. As someone else mentioned, those units run cold coils and usually have a thermostat that if the evap freezes, it shuts the unit down til it thaws. Newer high velocity air handlers require more runs than the old ones of the same size did. So it is likely that there is now insufficient ductwork. On the other hand, downsizing the unit could have solved that. Also there is usually a damper on the air handler to adjust static pressure which most dealers wouldn't bother with.



    SO: is it a high pressure switch or a freezestat shutting it down?



    If this dealer isn't up on high velocity, and since he was adjusting the charge at 60 out I'd wonder, he should call Space Pak's technical support
  • Techman
    Techman Member Posts: 2,144
    What was changed ?

    The compressor only, or the entire condensing unit?
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