I'm considering buying a portable AC rated at 4500 DOE BTU / 8000 ASHRAE BTU. My landlord says I can only have an AC 5000 BTUs or less.?

If I buy this particular AC, will I be in compliance?

5 Answers

  • elhigh
    Lv 7
    1 month ago
    Favourite answer

    The number that matters is the bigger one - 8000 ASHRAE BTU.  I'll explain:

    The portable AC's raw cooling power is equivalent to 8000 BTU.  Well and good, and that defines how much power the unit will consume, which is probably what the landlord is concerned with.  Bigger unit = bigger power, more likely to trip a breaker or something similar.  So as far as that goes, this portable is too big, end of story.  Keep shopping.

    But the way a portable works (usually, not always, get to this caveat in a moment) is this: it pulls air in from the room, uses that room air to cool its hot coils, and then throws that air outside through the hose.

    So part of the air that it is cooling, it is then throwing away.  And that's why that lower number is there: that's how much cooling you actually get: out of 8000 BTU of cooling power, you only get to keep about 4500 of it - barely more than half.

    This is why there are two ratings. The big number is the old kind of rating that only takes into account the unit's capacity. The smaller number is the one that tells you what you're actually going to get to keep out of that.

    If your landlord knew about this, he might be inclined to ban portable ACs altogether.  They are incredibly wasteful compared to even the cheapest, crudest window AC.

    Some portables do a little better, having two hoses: one to pull air in from outside, passes that over its hot coils, and then throws that hot air back outside again via the other hose.  Make no mistake, this is still a ridiculously inefficient system and creates something of a low-rent radiator in your room with that warm air hose, but it's better than the single-hose design.  Naturally these models cost more and will fill up a lot more of a window opening.

    In fact, they fill up so much of a window opening that it's easier to simply get a window AC and use that.  No hoses, takes up virtually no space in the room, and much more effective cooling.

  • 1 month ago

    Probably not meeting his goals, you might be able to claim ignorance or argue the exact meaning of the exact wording of the lease. Portable AC's really suffer from poor design characteristics. The big number basically indicates the cooling capacity of the guts, but the low rating is the relative cooling capacity when adjusted for the mechanical ventilation deficiencies. 

    The landlords restriction is a bit arbitrary, they could be concerned about sound or power, but actual BTU capacity doesn't correlate directly to either. The big concern is probably power. The landlord likely doesn't want to deal with getting called out because of tenants tripping breakers. Most places have laws saying you should have access to your breakers, but it doesn't necessarily happen, and even when tenants do have access often they don't know how to properly reset the breakers. Also tripping a breaker repeatedly will damage the breaker so it is possible he is trying to protect his building..

    If you don't want to cause issue I would look for a unit that uses less than 50% of the capacity of a circuit to allow capacity for other outlets on the same circuit. You would have to identify the actual breakers feeding the outlets to determine capacity. If you have 15A circuits that would be 7.5 amps/900 watts or if you have 20A circuits 10amps/1200 watts. 

  • 1 month ago

    4500 is less than 5000. Which part of COUNTING don't you understand?

  • 1 month ago

    You need to ask the landlord why only 5000 BTU. It is probably because of the circuit's capacity. If that is the case then you need to see what this unit pulls.

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  • 1 month ago

    Not likely, 8,000 is the cooling power, but that is reduced to 4,500 because of the heat it generates.

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