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Posted by bill on July 29, 2005, 5:28 pm
i would have thought that the seer does not consider the air handler
blower. but leaving that out still dont get you there. look here
if its 28.5 amps at 120v it just about figures (again we leave out
the blower fan)
On Fri, 29 Jul 2005 19:31:43 GMT, melbjer@hotmail.com wrote:
>
>I am looking afor a new central AC. I live in Florida so efficiency is
>important. I looked at Tranes, and found that the 4 1/2 ton unit I
>looked at was rated at a 14 SEER, yet the specs stated it drew 27.5
>amps for the compressor, an amp or so for the compressor fan, and 7
>amps for the air handler blower (full speed). Now 4 1/2 tons is 54000
>BTU's per hour, and the power draw is (27.5+1+7)amps X 220V, or 7800
>watts. This would seem to me to give a SEER of 6.9. This is less than
>half of the stated SEER of 14. Can anyone explain this? I looked at
>the ARI website and this seems to be the case for every manufacturer.
>If I buy a buy a 14 SEER 54000 BTU/hour AC, I would expect it to draw
>54000/14 watts, or 3850 watts. Can anyone explain this? Neither the
>Trane dealer or distributor could answer this. Thank you in advance.
>
>
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Posted by RP on July 29, 2005, 5:43 pm
melbjer@hotmail.com wrote:
> I am looking afor a new central AC. I live in Florida so efficiency is
> important. I looked at Tranes, and found that the 4 1/2 ton unit I
> looked at was rated at a 14 SEER, yet the specs stated it drew 27.5
> amps for the compressor, an amp or so for the compressor fan, and 7
> amps for the air handler blower (full speed). Now 4 1/2 tons is 54000
> BTU's per hour, and the power draw is (27.5+1+7)amps X 220V, or 7800
> watts. This would seem to me to give a SEER of 6.9. This is less than
> half of the stated SEER of 14. Can anyone explain this? I looked at
> the ARI website and this seems to be the case for every manufacturer.
> If I buy a buy a 14 SEER 54000 BTU/hour AC, I would expect it to draw
> 54000/14 watts, or 3850 watts. Can anyone explain this? Neither the
> Trane dealer or distributor could answer this. Thank you in advance.
The S in SEER stands for "Seasonal". Most of the run time during the
cooling season occurs at lower ambients, i.e. when the compressor draw
will typically run half or less than half of the RLA. You also need to
figure in power factor, which will improve your numbers. HTH.
hvacrmedic
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Posted by Joseph Meehan on July 29, 2005, 7:44 pm
melbjer@hotmail.com wrote:
> I am looking afor a new central AC. I live in Florida so efficiency is
> important. I looked at Tranes, and found that the 4 1/2 ton unit I
> looked at was rated at a 14 SEER, yet the specs stated it drew 27.5
> amps for the compressor, an amp or so for the compressor fan, and 7
> amps for the air handler blower (full speed). Now 4 1/2 tons is 54000
> BTU's per hour, and the power draw is (27.5+1+7)amps X 220V, or 7800
> watts. This would seem to me to give a SEER of 6.9. This is less than
> half of the stated SEER of 14. Can anyone explain this? I looked at
> the ARI website and this seems to be the case for every manufacturer.
> If I buy a buy a 14 SEER 54000 BTU/hour AC, I would expect it to draw
> 54000/14 watts, or 3850 watts. Can anyone explain this? Neither the
> Trane dealer or distributor could answer this. Thank you in advance.
As I recall SEER ratings are given based no actual test under specific
conditions. The amps listed are generally the highest amps expected, and an
AC will not draw the same amps under all conditions.
--
Joseph Meehan
Dia duit
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Posted by on July 30, 2005, 3:13 pm
The 27.5 amps were stated by the Trane distributor to be running amps,
not the peak amps on the housing. Perhaps he misspoke. The 7 amps on
the blower was peak, though. The blower moter is ¾ hp 240V, and runs
at close to peak most of the cycle, even though it's variable speed. I
ignored power factor to keep things simple, and used 220V rather than
240V to compensate, since the power factor according to Trane is
typical 0.9. Nevertheless, any adjustments to the 7800 watts
consumption is still very far from the 3800 watts implied by the SEER.
I appeciate everyone's ideas, The message I'm getting is that SEER is
determined by an average of EER's at different times of the season,
and was initially defined at 82 degrees outside ambient, and that
efficiency is defined under an unrealistic condition, is not constant,
and is much lower under normal summer conditions. I guess SEER is
useful to compare units, but I'd like to know before I buy what power
draw to expect, so I can compare other options. It seems a bit
dishonest to sell AC units in Florida, define SEER as BTU's per hour
over watts, and state an SEER of 14, if the unit is only going to run
at an efficiency of half that when it is used most. Anyway, thanks to
everone for their ideas.
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Posted by Carolina Breeze HVAC on July 30, 2005, 12:34 pm
>
>
> The 27.5 amps were stated by the Trane distributor to be running amps,
> not the peak amps on the housing. Perhaps he misspoke. The 7 amps on
> the blower was peak, though. The blower moter is ¾ hp 240V, and runs
> at close to peak most of the cycle, even though it's variable speed. I
> ignored power factor to keep things simple, and used 220V rather than
> 240V to compensate, since the power factor according to Trane is
> typical 0.9. Nevertheless, any adjustments to the 7800 watts
> consumption is still very far from the 3800 watts implied by the SEER.
> I appeciate everyone's ideas, The message I'm getting is that SEER is
> determined by an average of EER's at different times of the season,
> and was initially defined at 82 degrees outside ambient, and that
> efficiency is defined under an unrealistic condition, is not constant,
> and is much lower under normal summer conditions. I guess SEER is
> useful to compare units, but I'd like to know before I buy what power
> draw to expect, so I can compare other options. It seems a bit
> dishonest to sell AC units in Florida, define SEER as BTU's per hour
> over watts, and state an SEER of 14, if the unit is only going to run
> at an efficiency of half that when it is used most. Anyway, thanks to
> everone for their ideas.
>
>
>
>
You also know that your contractor must make over 150 measurements to make
sure you have the SEER you bought, right?
SEER for all intents, is marketing in this example.
You DO normally get a higher quality unit with the higher SEERs, but with
most, once you leave the 14SEER realm, and go into the 14+ you have over
engineered equipment, that while it IS of higher than 10 SEER quality, it
also is more expensive to replace, or work on.
If you want the best of both worlds, might I suggest GeoThermal, altho,
expect to pay out the nose for your initial installation, and you DO have to
make repairs to it every so often, but with the right installer, and the
right equipment, you can achieve SEER values that are sky high compared to a
conventional air to air unit.
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