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Comparable NEW Model?

Megs Member Posts: 4
Seems that I have gotten a few extra years out of my home A/C unit, considering I am under the impression that average life is 20 years. However, my Lennox A/C unit has bit the dust. It is a 1989, HS18-311-7P. If I am correct, it is a High Side 2.5 Ton Single Phase, 208-230 Volts unit.

My question is:

My house is a 1400sqft ranch.

Can you help me figure out a comparable replacement?
What It Is Is Beautiful.


    JUGHNE Member Posts: 8,533
    My Lennox book is from 1980, however they refer to a 311 unit to be 31,000 BTUH, which is a 2 1/2 Ton AC.

    Depending where you are located, a 3.5 ton unit is quite large for a 1400 sq ft house.
    The 2.5 may be a bit oversized. New installer should do a heat gain survey for your house. A 2 ton might be a better choice.
    The survey would tell you.
    Paul S_3
  • Megs
    Megs Member Posts: 4
    Ah! I just looked, again. You are CORRECT! It IS a 311. I must have looked the info up on the wrong chart. I was sure hoping the size was incorrect. These aren't cheap! Thanks!
    What It Is Is Beautiful.
    JUGHNE Member Posts: 8,533
    For sizing consideration; factors are your location, the construction envelope of your house and orientation to the sun.
    The cost difference between a 2 and 2.5 ton is minimal, the concern is to have the smallest unit that will cool the house on say a 90 to 95 degree day (depending upon your location). This would give you the most comfort and operating economy.
  • Megs
    Megs Member Posts: 4
    I guess what is confusing me the most is - this current model doesn't have the same coding as the new models. So, I don't know where to start. Before the unit died, it cooled the house amazingly. I'll do more research. However, I think the 2.5 ton is the correct size for my house. But, if I look at charts, a 2 ton might work, like you said.

    Basically, it'd be great to have this late model in an updated form.

    And, I understand, I am most-likely making this more difficult than it needs to be.

    But, as frugal as I am, I want to make the best decision with the money that I spend. I'd rather be spending it on my children! Although, this is sort of like that. LOL!

    I'm in 52591.
    And, my home is pretty much shaded from the sun, nearly all day long.
    What It Is Is Beautiful.
  • Ironman
    Ironman Member Posts: 6,398
    It looks like you're about midway between Des Moines and Davenport. I looked on two different design manuals and one called for 91* and the other for 94* design temp.

    There are a lot more things that have to be factored in. You really need to find a COMPETENT HVAC contractor who will do an ACCURATE load calculation based upon ACCA Manual J.

    As a contractor who's responsible for the performance of the equipment and systems that we install, I would never let a home owner dictate to me what SIZE equipment is needed. They can choose the level of efficiency and which brand from what we offer, but not the size - that's my responsibility.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    JUGHNE Member Posts: 8,533
    With the cooling season pretty well over you have all winter to pursue this. You could do your own heat loss/gain calculations yourself. There are some on line apps for that....someone younger than me can tell you how to get them.

    Some contractors will want to sell you a complete system, not always a bad idea. I assume your furnace is Natural gas and the same age of AC?

    Most economical would be a "dry" unit replacement......if still available. It uses the old type R-22.......not always a match to the inside coil.

    A new R-410A system needs a taller inside coil (usually) and maybe new lineset. Old furnace usually taller than new and can make for a tight fit in basement.
  • hvacfreak2
    hvacfreak2 Member Posts: 500
    Those HS and HP series units were fantastic and tough as nails. Sadly , I do not feel the same about that brand today however , nobody makes them like they used to I suppose.

    Do yourself a favor and get away from R-22 and have a decent 410 A system installed. R-22 has gotten out of hand price wise and the jury is out on the performance of the current replacements ( opinion ). The existing duct system is an overlooked factor in replacement work more often than not. It's great to say that a capacity change from the existing will do this or that , but the current duct system will ultimatly determine the net effect of those changes. I agree to do a load calculation if there is a question of the existing capacity .

    Best of luck on your project .


    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

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  • John Mills_5
    John Mills_5 Member Posts: 935
    Ironman said:

    There are a lot more things that have to be factored in. You really need to find a COMPETENT HVAC contractor who will do an ACCURATE load calculation based upon ACCA Manual J.

    That's the key right there. Don't guess. Charts don't mean anything, sq ft alone doesn't either.

    Don't just replace the outdoor unit. We probably took out more HS18s in the day due to leaking indoor coils and rusted drain pans than we did problems outside.
  • Megs
    Megs Member Posts: 4
    With all of your answers, I have come to realize - this project is well beyond my hands. I have a professional coming to check things out, tomorrow!

    Some things are better left to NOT me!

    Thank you, all!
    What It Is Is Beautiful.
  • ChrisJ
    ChrisJ Member Posts: 11,784
    How much did your old unit run during the hottest months?
    Did it often run continuously, or close to it, but keep the house nice and comfortable?

    What about during heat waves?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment