Re: Replacement window air conditioner is weak

"Eric in North TX" <tinedog@xxxxxxxxx> wrote in message news:42aad465-8c83-4f85-bc2f-43dc78f081f1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jun 29, 10:05 pm, "Smarty" <nob...@xxxxxxxxxx> wrote:
A 14 year old Sharp window air conditioner rated at 10,000 BTU/hr was
recently replaced with a much more efficient 12,000 new Sharp window unit.
The replacement was motivated by the higher energy efficiently, and my
desire to get a bit more cooling.

The replacement unit does not deliver nearly as much cooling as the
original, despite being brand new and having 20% higher rated BTU/hr output.

It does ultimately achieve adequate cooling, but with much longer compressor
cycles, and thus higher operating costs.

Is there any objective measurement I can perform to demonstrate that this
unit is not putting out anywhere near its rated capacity? I cannot find any
published data to evaluate delta T, discharge air temperature, or other
quantitative evidence. I ultimately have to convince the service people that
this unit is defective.

Many thanks for any suggestions.

Have you verified higher operating costs? I mean, have you had a bill
yet? My experience says longer cycles are desirable, as it
dehumidifies better, often making it quite comfortable at higher
temperatures.




Thanks for replying.
To answer both your question as well as the similar comments of "Larry the Snake Guy":

Both the old 10,000 BTU/hr and the new 12,000 BTU/hr air conditioner draw nearly the same current when running at maximum fan speed and with compressor engaged, about 9.6 amps. The older unit was a 10,000 BTU/hr unit, and the new unit is rated at 12,000 BTU/hr. The higher energy efficiency rating of the new unit (Energy Star / 10.8) accounts for the fact that it (supposedly) can produce 20% more BTU/hr despite drawing the same current as the older, less powerful unit.

The difference in cooling capacity is quite noticeable, but unfortunately in exactly the opposite direction from what I intended:

I get less than a 1.5 degree temperature drop per hour with the new unit. With an 85 degree outdoor temperature, it will now take roughly 8 hours to pull the room temperature down to the low to mid 70's.

With the older unit, I easily got well over 2.0 degree drop per hour, maybe even 2.5. On an 85 degree day, the same room was cooled in well below 4 hours, maybe closer to 3 hours to a 75 degree temperature.

It doesn't take an electric bill or a PhD in thermodynamics to see that the newer unit is cooling far less quickly, and is drawing nearly identical amperage (at the same line voltage of about 116 VAC) when compared to the older unit.

I never measured discharge air temperature on the old unit, but the new unit puts out cool air whereas the older unit put out truly cold air. I can easily measure the temperature of the cooled air which the new unit discharges if that would be useful. The discharge air velocity of the new unit seems roughly the same as the older unit, both of which are operated at their maximum (High) blower speeds.

So I am back to my original question as to how to measure whether this new unit is working correctly.

If I had not owned the prior unit, same manufacturer, 20% lower BTU/hr rating for the last 14 years and grown very accustomed to its performance, I would not have any complaints about the new unit, since it does cool. It just takes a lot longer, puts out noticeably less cold air, and draws as much power as the prior unit but for nearly double the length of compressor cycles.

If anything, one should expect that a higher output unit would have shorter compressor cycles, all other things being equal. The new unit compressor runs easily twice as long as the older one did to achieve similar cooling.

I am concerned that not only do I suffer the increased energy cost as well as the increased noise now, since the compressor is running nearly constantly, but also the fact that as we get further into the summer season and outdoor temperatures rise to 95 or perhaps higher that this new unit will not have the ability to achieve greater temperature drops, since the compressor cycle now is nearly 100% with outdoor temps closer to low to mid 80's.

Again, I welcome suggestions, and thank you in advance for your help and advice.




.

Relevant Pages

  • Re: Replacement window air conditioner is weak
    ... The replacement was motivated by the higher energy efficiently, ... Both the old 10,000 BTU/hr and the new 12,000 BTU/hr air conditioner ... with compressor engaged, about 9.6 amps. ... I get less than a 1.5 degree temperature drop per hour with the new ...
    (alt.home.repair)
  • Re: Replacement window air conditioner is weak
    ... Both the old 10,000 BTU/hr and the new 12,000 BTU/hr air conditioner draw ... compressor engaged, about 9.6 amps. ... I get less than a 1.5 degree temperature drop per hour with the new unit. ...
    (alt.home.repair)
  • Re: Replacement window air conditioner is weak
    ... Both the old 10,000 BTU/hr and the new 12,000 BTU/hr air conditioner draw ... compressor engaged, about 9.6 amps. ... I get less than a 1.5 degree temperature drop per hour with the new unit. ...
    (alt.home.repair)
  • Re: Replacement window air conditioner is weak
    ... despite being brand new and having 20% higher rated BTU/hr ... > published data to evaluate delta T, discharge air temperature, or other ... compressor engaged, about 9.6 amps. ... I get less than a 1.5 degree temperature drop per hour with the new unit. ...
    (alt.home.repair)
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