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Default Normal A/C on / off cycle durations?

Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.

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Default Normal A/C on / off cycle durations?

glynndaddy wrote:

Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes. Thanks for your help.


At those temps and TSTAT setting the unit is short cycling!
Each time it starts a run cycle it takes nearly 5 minutes to reach its
optimal cooling capacity at those temps and humidity levels.

Where is the RM TH located? Maybe it needs shielding from cool air
streams, etc.

They should make a digital RM TH that has an on/off temp differential
setting.
You could then set it to cycle on at 79 and off even a low as 73-F.
Use large floor fans to keep the air circulating as this will add to
your comfort.
Take a look at the "Human Comfort Zone Chart," on the linked page below.

The way most RM THs are now is that they have a cooling anticipator that
aids in keeping the temperature very close to the TH setting.
That is the wrong way to go if you want and need longer cycles to reduce
humidity levels and increase the operating SEER levels.

- udarrell - Darrell

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Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
http://www.udarrell.com/air-conditio...tent-heat.html
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Default Normal A/C on / off cycle durations?

On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:

Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.


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Default Normal A/C on / off cycle durations?

78f 72% humidity is not a comfortable setting. Your thermostat might
have a setting to increase cycle time, a longer time is also easier on
the equipment.

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Default Normal A/C on / off cycle durations?

m Ransley wrote:

78f 72% humidity is not a comfortable setting. Your thermostat might
have a setting to increase cycle time, a longer time is also easier on
the equipment.


I believe the OP was referring to outdoor humidity, not indoor. Were it
72% humidity indoor I think the OP would be complaining of problems
other than short cycle times.

Pete C.


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Default Normal A/C on / off cycle durations?

Thanks to everyone for your help.

Is a thermostat, TSTAT and RM TH all the same thing?

If a properly running systems run for long periods of time, doesn't
that translate to high energy bills? What would be a reasonable ratio
of on to off time?

I didn't want to take much of anyone's time, but I guess I should
disclose that my system is not running right. It was installed in a
new house four years ago. I've had to have the system recharged 3
times, the last time a few weeks ago. The previous two times fixed the
short cycling, but not this time.

The AC company found a leak in my evaporator coil. I guess it needs to
be fixed, but it's going to be expensive. I was hoping that the
recharging would buy me some time, but i guess the leak has gotten too
big.

Lastly, when they found the problem, the guy did not reseal the
evaporator coil housing access panel. I just went up in the attic and
noticed there is some cold air coming out. I guess i will get up there
with duct tape, but I can't imagine it having that big an effect.
There is also air coming out of my drain pipe (because there is no cap
on it). I guess I will put some tape on that too.

Thanks everyone.

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Default Normal A/C on / off cycle durations?

JimL wrote:

On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:


Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.



yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.


No matter how hot it is, it can get hotter. I would say a well designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective removing
the humidity.

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Default Normal A/C on / off cycle durations?

On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:

JimL wrote:

On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:


Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.



yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.


No matter how hot it is, it can get hotter. I would say a well designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective removing
the humidity.


No,No.
You DO want to run out of reserve. A well designed system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


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Default Normal A/C on / off cycle durations?


"glynndaddy" wrote in message
ups.com...
Thanks to everyone for your help.

Lastly, when they found the problem, the guy did not reseal the
evaporator coil housing access panel. I just went up in the attic and
noticed there is some cold air coming out. I guess i will get up there
with duct tape, but I can't imagine it having that big an effect.
There is also air coming out of my drain pipe (because there is no cap
on it). I guess I will put some tape on that too.


NEVER USE DUCT TAPE! Use foil tape as it will last. Duct tape will fail
over time.


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Default Normal A/C on / off cycle durations?

JimL wrote:

On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:


JimL wrote:


On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:



Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.



No matter how hot it is, it can get hotter. I would say a well designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective removing
the humidity.



No,No.
You DO want to run out of reserve. A well designed system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


With global warming, the next summer it'll be 90, 91, 92 ...

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minimize spam. Our true address is of the form .


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Default Normal A/C on / off cycle durations?

Thanks to everyone again for your help.

My builder has contacted the AC contractor who installed the system and
they've agreed to replace the evaporator coil. I hope they do a good
job. Last month my bill was $270 to cool 2400 sq ft to 79 degrees.

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On 18 Jul 2006 18:06:09 -0700, "glynndaddy"
wrote:

Thanks to everyone again for your help.

My builder has contacted the AC contractor who installed the system and
they've agreed to replace the evaporator coil. I hope they do a good
job. Last month my bill was $270 to cool 2400 sq ft to 79 degrees.


I was just looking at warranty period on Goodman coils and the
standard warranty is 10 years on the coil with a new system and 5
years otherwise. Lifetime on the heat exchanger.

Good for you on getting a new coil. I suspect a botched install,
not a bad coil.






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Default Normal A/C on / off cycle durations?

CJT wrote:
JimL wrote:

On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:


JimL wrote:


On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:



Is there a general rule-of-thumb for how long an air conditioner
should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've
searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.



No matter how hot it is, it can get hotter. I would say a well
designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective
removing
the humidity.



No,No. You DO want to run out of reserve. A well designed
system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


With global warming, the next summer it'll be 90, 91, 92 ...

I know from BITTER experience that you do NOT want a AC system that runs
from 10:00am to 10:00pm. Power bill DOUBLES. House is livable, but
uncomfortable, especially when guests are over.

50% duty cycle, but no more than once an hour, certainly no more than
once every 30 minutes. Any faster cycling than this is dangerous for
the compressor.

A house that is 'adequately' plugged against air leaks, and has
'adequate' insulation should not have a duty cycle of greater than 50%
and really should have a duty cycle of under 25%. Air leak plugs are
the new hot button, now that most new homes have at least R38 in the
ceiling and R24 in the walls, Course if we do manage to plug those
uncontrolled air leaks, then the house accumulates odors (cooking, body
odor - human and pets, solvents, cleaning fluids, paint, plastics......)
and we must then install a controlled ventilator.

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Default Normal A/C on / off cycle durations?

On Wed, 19 Jul 2006 11:56:34 GMT, Robert Gammon
wrote:

CJT wrote:
JimL wrote:

On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:


JimL wrote:


On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:



Is there a general rule-of-thumb for how long an air conditioner
should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've
searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.



No matter how hot it is, it can get hotter. I would say a well
designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective
removing
the humidity.


No,No. You DO want to run out of reserve. A well designed
system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


With global warming, the next summer it'll be 90, 91, 92 ...

I know from BITTER experience that you do NOT want a AC system that runs
from 10:00am to 10:00pm. Power bill DOUBLES. House is livable, but
uncomfortable, especially when guests are over.

50% duty cycle, but no more than once an hour, certainly no more than
once every 30 minutes. Any faster cycling than this is dangerous for
the compressor.

A house that is 'adequately' plugged against air leaks, and has
'adequate' insulation should not have a duty cycle of greater than 50%
and really should have a duty cycle of under 25%. Air leak plugs are
the new hot button, now that most new homes have at least R38 in the
ceiling and R24 in the walls, Course if we do manage to plug those
uncontrolled air leaks, then the house accumulates odors (cooking, body
odor - human and pets, solvents, cleaning fluids, paint, plastics......)
and we must then install a controlled ventilator.


Wrong again.


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Default Normal A/C on / off cycle durations?

JimL wrote:
On Wed, 19 Jul 2006 11:56:34 GMT, Robert Gammon
wrote:


CJT wrote:

JimL wrote:


On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:



JimL wrote:



On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:




Is there a general rule-of-thumb for how long an air conditioner
should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've
searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.



No matter how hot it is, it can get hotter. I would say a well
designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective
removing
the humidity.


No,No. You DO want to run out of reserve. A well designed
system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.



With global warming, the next summer it'll be 90, 91, 92 ...


I know from BITTER experience that you do NOT want a AC system that runs


from 10:00am to 10:00pm. Power bill DOUBLES. House is livable, but


uncomfortable, especially when guests are over.

50% duty cycle, but no more than once an hour, certainly no more than
once every 30 minutes. Any faster cycling than this is dangerous for
the compressor.

A house that is 'adequately' plugged against air leaks, and has
'adequate' insulation should not have a duty cycle of greater than 50%
and really should have a duty cycle of under 25%. Air leak plugs are
the new hot button, now that most new homes have at least R38 in the
ceiling and R24 in the walls, Course if we do manage to plug those
uncontrolled air leaks, then the house accumulates odors (cooking, body
odor - human and pets, solvents, cleaning fluids, paint, plastics......)
and we must then install a controlled ventilator.



Wrong again.


If it runs constantly just to stay even, it'll take forever to recover
after a power failure.

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minimize spam. Our true address is of the form .


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Default Normal A/C on / off cycle durations?

replying to glynndaddy, Denco AC - Carrier Dealer - 28 years experience-
Licensed in Texas wrote:
glynndaddy wrote:

Thanks to everyone for your help.
Is a thermostat, TSTAT and RM TH all the same thing?
If a properly running systems run for long periods of time, doesn't
that translate to high energy bills? What would be a reasonable ratio
of on to off time?
I didn't want to take much of anyone's time, but I guess I should
disclose that my system is not running right. It was installed in a
new house four years ago. I've had to have the system recharged 3
times, the last time a few weeks ago. The previous two times fixed the
short cycling, but not this time.
The AC company found a leak in my evaporator coil. I guess it needs to
be fixed, but it's going to be expensive. I was hoping that the
recharging would buy me some time, but i guess the leak has gotten too
big.
Lastly, when they found the problem, the guy did not reseal the
evaporator coil housing access panel. I just went up in the attic and
noticed there is some cold air coming out. I guess i will get up there
with duct tape, but I can't imagine it having that big an effect.
There is also air coming out of my drain pipe (because there is no cap
on it). I guess I will put some tape on that too.
Thanks everyone.




A refrigerant leak will have a huge impact on run time. The lower it gets,
the longer it will run. Adding more Freon will never solve the problem. A
a/c system is like a car tire in that it is air tight. If your car has a
low tire it is because it has a leak, adding air does nothing to repair
the tire or the leak. The same rule applies to a a/c system. If your unit
is 4 years old it should still be under warranty by the manufacturer and a
repair would cost you labor and refrigerant, The coil would be replaced by
the manufacturer. The leak will only get worse. And in time I running the
system low on refrigerant will/can destroy the compressor. As for run
time, the length a ac unit runs is determined by variables such as outdoor
temperature, heat gains through windows and doors and the amount of
insulation in your attic. These same variables determine the length of
tine the unit is off. I just a had a conversation with a customer who's
old system ran non stop, we installed a new system one ton larger and now
it runs 6-7 minutes and is off for 14-16 minutes. So the run time is 18
minutes per hour instead of running 20 hours a day like the old undersized
unit.



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Default Normal A/C on / off cycle durations?

On Tuesday, July 18, 2006 12:21:05 PM UTC-4, JimL wrote:
On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:

JimL wrote:

On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:


Is there a general rule-of-thumb for how long an air conditioner should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.


No matter how hot it is, it can get hotter. I would say a well designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective removing
the humidity.


No,No.
You DO want to run out of reserve. A well designed system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


BS. If it's falling behind on the hottest day in a decade,
then it's also taking a long time to cool down if it's been off
and you come home from a trip
and probably not performing very well on a lot of days that aren't
the hottest in a decade, but close enough. I want some decent reserve.
I agree that you don't want it grossly oversized, because that
causes problems too.
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Default Normal A/C on / off cycle durations?

On Wednesday, July 19, 2006 7:56:34 AM UTC-4, Robert Gammon wrote:
CJT wrote:
JimL wrote:

On Mon, 17 Jul 2006 22:10:51 GMT, CJT wrote:


JimL wrote:


On 16 Jul 2006 22:13:23 -0700, "glynndaddy"
wrote:



Is there a general rule-of-thumb for how long an air conditioner
should
run and how long it should stay off? I realize this probably depends
on a variety of variables, but is there a rule-of-thumb. I've
searched
quite a bit and can not seem to find an answer.

If it helps, my house is 1 story, 2400 sq ft. I have the thermostat
set at 78. It is 85 degrees outside, humidy 72%.

Right now, my a/c stays on for 8 - 10 minutes and goes off for 7 - 9
minutes.

Thanks for your help.


yeah, what darrel said plus, my thermastat has a 1 or 2 degree
differential setting. The 2 setting makes it run longer between
cycles.

This time of year, in the hottest part of the day, a well designed
system should be running just about all the time.



No matter how hot it is, it can get hotter. I would say a well
designed
system should be running _most_ of the time; you never want to run out
of reserve. If it's at a 50-60% duty cycle, it'll be effective
removing
the humidity.


No,No. You DO want to run out of reserve. A well designed
system should
fall behind on the hottest day of the decade. It won't be able to
keep up. Your thermostat will be set at 78 but the temp will creep up
to 80, 81, 82...... etc.


With global warming, the next summer it'll be 90, 91, 92 ...

I know from BITTER experience that you do NOT want a AC system that runs
from 10:00am to 10:00pm. Power bill DOUBLES. House is livable, but
uncomfortable, especially when guests are over.

50% duty cycle, but no more than once an hour, certainly no more than
once every 30 minutes. Any faster cycling than this is dangerous for
the compressor.


Says who? If an AC cycling more than once every 30 mins
was "dangerous", there would be a lot of broken AC's out there.




A house that is 'adequately' plugged against air leaks, and has
'adequate' insulation should not have a duty cycle of greater than 50%
and really should have a duty cycle of under 25%.


Really? Even on one of the hottest days of the year?


Air leak plugs are
the new hot button, now that most new homes have at least R38 in the
ceiling and R24 in the walls, Course if we do manage to plug those
uncontrolled air leaks, then the house accumulates odors (cooking, body
odor - human and pets, solvents, cleaning fluids, paint, plastics......)
and we must then install a controlled ventilator.


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Default Normal A/C on / off cycle durations?

replying to glynndaddy, Mike Name wrote:
Wow you set your stat at 78 degrees? Why even bother with owning an a/c unit,
get a dehumidifier. Seriously I am not a freeze freak and find 74 degrees to
get the top temp for comfort but 73 usually is where I set it to keep the wife
from complaining and guests.

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Default Normal A/C on / off cycle durations?

On Monday, May 1, 2017 at 10:14:11 AM UTC-4, Mike Name wrote:
replying to glynndaddy, Mike Name wrote:
Wow you set your stat at 78 degrees? Why even bother with owning an a/c unit,
get a dehumidifier. Seriously I am not a freeze freak and find 74 degrees to
get the top temp for comfort but 73 usually is where I set it to keep the wife
from complaining and guests.

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Another clueless HomeMoaner. If it's 100 outside, will a dehumidifier
keep a house at 78F?


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On Monday, May 1, 2017 at 11:15:02 AM UTC-4, trader_4 wrote:
On Monday, May 1, 2017 at 10:14:11 AM UTC-4, Mike Name wrote:
replying to glynndaddy, Mike Name wrote:
Wow you set your stat at 78 degrees? Why even bother with owning an a/c unit,
get a dehumidifier. Seriously I am not a freeze freak and find 74 degrees to
get the top temp for comfort but 73 usually is where I set it to keep the wife
from complaining and guests.

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Another clueless HomeMoaner. If it's 100 outside, will a dehumidifier
keep a house at 78F?


Well, that depends on whether we're recovering the latent heat from condensing the water.

Oh wait, we had this conversation with Stormy. never mind.
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replying to Mike Name, Djayhan wrote:
Thank you, that's about the only sentence that makes sense on this page.

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replying to trader_4, Djayhan wrote:
A little exaggerated like 100 degrees too, but 78 degrees seems pretty
pointless if you own an AC unit. 72° is considered be optimal 10 picture for
human beings to dwell in so why have been air conditioning unit attached to
your house if you're not gonna use it at optimum and temperatures or another
words he so conservative that you're never comfortable live a little and let
your $ serve you.

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On 5/2/2017 8:14 PM, Djayhan wrote:
replying to trader_4, Djayhan wrote:
A little exaggerated like 100 degrees too, but 78 degrees seems pretty
pointless if you own an AC unit. 72° is considered be optimal 10 picture
for
human beings to dwell in so why have been air conditioning unit attached to
your house if you're not gonna use it at optimum and temperatures or
another
words he so conservative that you're never comfortable live a little and
let
your $ serve you.

There are plenty of places in North American that are common with 100
degrees in summer. Keeping the house at 78 and dry is quite
comfortable. Less shock to the body going in and out too.

Human comfort varies. 72 is not bad is summer, but in winter I like 65
for sleeting 70 for the rest of the day.
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replying to Denco AC - Carrier Dealer - 28, Vld5491 wrote:

Denco - AC - Carrier dealer you know I am from California and just had a new
AC condenser, coil and furnace replaced. I am experiencing exactly the same as
one of your customer after upgrading my AC to a 4t from a 3t unit, it now
running like 8-10 mins and shuts down from 18 - 22 mins. But I was wondering
cause I have not seen my electric bill after this installation, would this
lower or raise my electricity bill?Thanks

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On Saturday, May 27, 2017 at 1:44:15 AM UTC-4, Vld5491 wrote:
replying to Denco AC - Carrier Dealer - 28, Vld5491 wrote:

Denco - AC - Carrier dealer you know I am from California and just had a new
AC condenser, coil and furnace replaced. I am experiencing exactly the same as
one of your customer after upgrading my AC to a 4t from a 3t unit, it now
running like 8-10 mins and shuts down from 18 - 22 mins. But I was wondering
cause I have not seen my electric bill after this installation, would this
lower or raise my electricity bill?Thanks

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If it's doing that when temps are moderate, it's probably fine.
If it's doing that when temps are hot, then it's oversized.
Was there a problem with the existing 3T not cooling enough?
What was the reason for going larger? As to the electric bill,
probably won't make any significant difference due to the timing.
It will use less electricity if it replaced an old honker.
The big downside to oversizing is that it won't run enough to
remove humidity on moderate days, won't run as long as it should
to mover air around and get balanced, etc.
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replying to trader_4, Vld5491 wrote:
We decided to upgrade from 3t to 4t because we have a townhouse with 1708
sqft. We had to close 3 registers/vents to get out 3 bedrooms to get to
comfortable level. Plus the contractor says in every 400 sq ft requires 1
tonage. With regards to humidity here in CA we have a very low humidity and we
are still on moderate weather, summer starts in June. Another thing that came
to mind is the frequency of the ac going on and off. Is this not bad for the
unit? Well the ac cool up pretty fast comparing to our old honker that's for
sure. Thanks for your infos. Have a wonderful memorial weekendðŸ˜

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On Sunday, May 28, 2017 at 5:14:05 PM UTC-4, Vld5491 wrote:
replying to trader_4, Vld5491 wrote:
We decided to upgrade from 3t to 4t because we have a townhouse with 1708
sqft.


3 tons should be plenty for 1700 so ft.



We had to close 3 registers/vents to get out 3 bedrooms to get to
comfortable level.


Probably because something is wrong with the system, design, etc.



Plus the contractor says in every 400 sq ft requires 1
tonage.


That contractor is an idiot. Following that logic, a 2500 so ft house needs 6 tons? A 3000 so ft needs 7+ tons? You can do a manual J calculation which factors in size, insulation,windows, exposure, climate to get a correct number. That's why you have a system that is short cycling.




With regards to humidity here in CA we have a very low humidity and we
are still on moderate weather, summer starts in June. Another thing that came
to mind is the frequency of the ac going on and off. Is this not bad for the
unit?


It's less stress on the system and more energy efficient if it's correctly sized, that's true. But it doesn't mean that it's going to burn up or use a lot more energy either. I'd be more concerned about having it run enough to get an even temp.


ell the ac cool up pretty fast comparing to our old honker that's for
sure. Thanks for your infos. Have a wonderful memorial weekendðŸ˜

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On 5/28/2017 7:22 PM, trader_4 wrote:
On Sunday, May 28, 2017 at 5:14:05 PM UTC-4, Vld5491 wrote:
replying to trader_4, Vld5491 wrote:
We decided to upgrade from 3t to 4t because we have a townhouse with 1708
sqft.


3 tons should be plenty for 1700 so ft.


I have 2100 sq. ft. and cool it with 2 1/2 ton. Of course, conditions
vary and the contractor should have run the manual J calculations.
http://www.loadcalc.net/
http://www.wikihow.com/Calculate-BTU...g_Capacity_sub


We had to close 3 registers/vents to get out 3 bedrooms to get to
comfortable level.


Probably because something is wrong with the system, design, etc.



Plus the contractor says in every 400 sq ft requires 1
tonage.


That contractor is an idiot. Following that logic, a 2500 so ft house needs 6 tons? A 3000 so ft needs 7+ tons? You can do a manual J calculation which factors in size, insulation,windows, exposure, climate to get a correct number. That's why you have a system that is short cycling.


Agree on the idiot part.. Looks like the OP will have a cold muggy
summer.
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replying to trader_4, Vld5491 wrote:
Thank you so much for the infos. Have a nice dayðŸ˜

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replying to Mike Name, JoeBlow wrote:
We keep our thermostat set on 78 in the summer. If we were to set it at 73 we
would have to wear sweatpants and socks just to keep from freezing! 73 is what
our basement temp is and it's too chilly down there. I like sitting around in
my underwear and a t-shirt during the summer, so 73 would be too cold. Plus,
we don't want to give any more money to the energy company than we have to! In
the winter we set it on 67 and bundle up in sweat pants and sweat shirt and
socks. Plus, when I'm sitting down, I have a blanket covering my feet and
legs.

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The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.
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On Sunday, September 17, 2017 at 12:24:31 PM UTC-4, wrote:
The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.


Find a thermostat that lets you adjust how often it runs, either by
allowing adjustment of the swing points, ie does it go on when the temp
drops by .5 deg or 1 deg, etc., or by setting the number of cycles per
hour. I have a Honeywell VisionPro and it uses the latter method.
Since you're concerned about humidity, I'd get one that also controls
that. Essentially, if you set it to say 75F and humidity is above a
set point, it will run it anyway within limits, allowing temp to drop
to say 73 or 74 to reduce humidity. I don't have that, Honeywell
probably has ones that do. I've been very happy with the VP series
that I've had. You can find them on Ebay. Also, if I was buying one
today I'd get one that is internet connected. It's a nice feature
where if you're coming home early, from a trip, etc you can fire
it back up from your phone. Also, you can check while you're away,
see what the temp is, etc.
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On Sun, 17 Sep 2017 09:24:25 -0700 (PDT), wrote:

The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info
here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.


I live in your area, FWIW. Cycling has a lot to do with your thermostat's "anticipator."
I think I have mine maxed to avoid excessive cycling.
Thermostat placement is also important, as is air circulation in your home.
Unless it's in the 90's, mine cycles only enough to reach the temp the thermostat is set
to. That doesn't mean it's the same temp everywhere in the house, just the hallway where
the thermostat is mounted on the wall.
It's important to have good air circulation to avoid hot spots. I have ceiling fans.
I'll try to remember to time the cycling for you today. We should be close to the same
temp.
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Thank You Vic and trader_4 for your specificity. I am so upset about this situation, so helpful answers are appreciated. As a single female, I'm tired of getting screwed by contractors. The upsell of the 2.5 ton unit for my small place was where the problems started. It sounded like a jet was taking off in my living room every time the blower started. The humidity is so high, I have to run the A/C until I'm freezing here at 68 or 69 degrees to get it down to 55%. Since I complained to the contractor right away, they replaced the components outside with smaller ones, but I don't think that helped. At this point I'm not sure what is reasonable to ask them to do. I believed them when they said "stuff happens" when the blower motor went out a couple of weeks ago when the thing was only 13 months old. Reading these threads and some articles, I'm finding out just how hard it is on certain components like motors and such when its constantly starting from zero. Someone likened it to turning your car off at every stop light. So, I will no longer buy the "stuff happens" theory especially if someone can tell me my system is short cycling. Today it was in the lower 80s outside. I was trying to maintain a 74 degree temp. The A/C was on for 3-7 minutes and off for 7-12 minutes, most of the day. BTW, the thermostat is in a little hallway. No sunlight, drafts or vents. And also, the lower bills I was promised never happened. My new, high efficiency system is not so efficient. Since the system is new, replacing it is not a cost-effective option. Maybe your advice regarding a thermostat that can "stretch" the cycle a bit could save on some wear and tear.


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On Monday, September 18, 2017 at 12:24:30 AM UTC-4, wrote:
Thank You Vic and trader_4 for your specificity. I am so upset about this situation, so helpful answers are appreciated. As a single female, I'm tired of getting screwed by contractors. The upsell of the 2.5 ton unit for my small place was where the problems started. It sounded like a jet was taking off in my living room every time the blower started. The humidity is so high, I have to run the A/C until I'm freezing here at 68 or 69 degrees to get it down to 55%. Since I complained to the contractor right away, they replaced the components outside with smaller ones, but I don't think that helped. At this point I'm not sure what is reasonable to ask them to do. I believed them when they said "stuff happens" when the blower motor went out a couple of weeks ago when the thing was only 13 months old. Reading these threads and some articles, I'm finding out just how hard it is on certain components like motors and such when its constantly starting from zero. Someone likened it to turning your car off at every stop light. So, I will no longer buy the "stuff happens" theory especially if someone can tell me my system is short cycling. Today it was in the lower 80s outside. I was trying to maintain a 74 degree temp. The A/C was on for 3-7 minutes and off for 7-12 minutes, most of the day. BTW, the thermostat is in a little hallway. No sunlight, drafts or vents. And also, the lower bills I was promised never happened. My new, high efficiency system is not so efficient. Since the system is new, replacing it is not a cost-effective option. Maybe your advice regarding a thermostat that can "stretch" the cycle a bit could save on some wear and tear.


While it's true that short cycling puts more strain on the motors and isn't as efficient, it's not why your motor failed in just one year. It might make a difference of it lasting 15 years instead of 20 or something like that, but not failing in just a year. Was it a basic motor or the new fancy variable speed ECM type? The latter is more failure prone. I had the ECM fan on the outdoor condenser go on my theme after just 2 years. That's what you get in the quest for higher seers. I replaced it myself for $90 with a basic standard motor, which was available from many sources and fit. A new ECM one would have cost 3x or 4x that.

If you replace the thermostat and stop the short cycles, you may notice an improvement in energy use too. Download the install manuals for any new ones you're considering. I know on the Honeywell vision pro you can set the number of cycles per hour. They also have adaptive recovery, where after having the thermostat set back, when you set the time for it to resume, you pick the time and temp you want and it figures out how much earlier to start it to reach that temp at that time,based on history and current conditions..
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On Sunday, September 17, 2017 at 11:24:31 AM UTC-5, wrote:
The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.



I've a question for you. The size of your AC unit seems to be too big for your small well insulated house, did the HVAC contractor do any calculations or take into account the energy saving measures you have taken? I've a few more questions I'm formulating since one of the things I did when I was still working was HVAC system installation and repair. ヽ(ヅ)ノ

[8~{} Uncle AC Monster
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On Mon, 18 Sep 2017 18:48:05 GMT, Wayne Boatwright wrote:

On Sun 17 Sep 2017 10:27:43a, Vic Smith told us...

On Sun, 17 Sep 2017 09:24:25 -0700 (PDT),
wrote:

The question was about short cycling and how he could determine if
his was short cycling.

snip

I live in your area, FWIW. Cycling has a lot to do with your
thermostat's "anticipator." I think I have mine maxed to avoid
excessive cycling. Thermostat placement is also important, as is
air circulation in your home. Unless it's in the 90's, mine cycles
only enough to reach the temp the thermostat is set to. That
doesn't mean it's the same temp everywhere in the house, just the
hallway where the thermostat is mounted on the wall.
It's important to have good air circulation to avoid hot spots. I
have ceiling fans. I'll try to remember to time the cycling for
you today. We should be close to the same temp.


I've never checked the settings inside my thermostat as I've had no
reason to. I have checked the temperature in every room except the
kitchen (it has no vent and is closed off except for the doorway.
OUr temperature variant is no more than 2 degrees amongst all the
rooms. Our unit cycles about 3 times an hour. We live in central
AZ. We do use ceiling fans to help average out the temperature, and
we keep the thermostat set at 77° F.


Mine was cycling about 3 times an hour yesterday. It was 82 outside and it was set at 79.
I was wrong about having an adjustable anticipator - that was my old thermostat.
The Honeywell I have now has CPH (cycles per hour) and since I don't remember programming
it, it's probably set to the default, which is 4 (every 15 minutes.)
The thermostat must have anticipator logic (aka hysteresis) built in. They don't give
such technical details in the user manual. From experience, it's about 1 degree F.
Patricia can check the user manual for her thermostat. Should be able stop the
short-cycling if the thermostat setting is causing it. That's all I know.

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On Monday, September 18, 2017 at 12:27:05 PM UTC-4, Uncle Monster wrote:
On Sunday, September 17, 2017 at 11:24:31 AM UTC-5, wrote:
The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.



I've a question for you. The size of your AC unit seems to be too big for your small well insulated house, did the HVAC contractor do any calculations or take into account the energy saving measures you have taken? I've a few more questions I'm formulating since one of the things I did when I was still working was HVAC system installation and repair. ヽ(ヅ)ノ

[8~{} Uncle AC Monster



I saw her say that they put in a new 2.5 ton, then swapped it out two
weeks later for 2 ton. But I missed that the place is only 750 sq ft!
That's like three 20 x 12 rooms. We don't know the rest of the situation,
but I agree, it sure seems oversized, still, to me. 2.5 tons is 30K BTUs.
It's like having a 10K BTU unit in each room. Would you buy a 10K
unit for that size room? Even more remarkable is that
they had a 2.5 in there, knew that was too big, but then only went down
to 2.0? It's probably useable with that size if she gets the short
cycling fixed, but it's most likely not optimum either.

What was in there before they put the new 2.5 ton in? What was the
experience with the old unit?
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On 9/18/2017 4:29 PM, trader_4 wrote:

On Monday, September 18, 2017 at 12:27:05 PM UTC-4, Uncle Monster wrote:

On Sunday, September 17, 2017 at 11:24:31 AM UTC-5, wrote:

The question was about short cycling and how he could determine if his was short cycling. Most of the posts here were about what temp is comfortable and other useless information. I love the "wrong again" comment. That was also helpful especially without a reason. I'm pretty sure my one year old, 7K, 2.5 ton system is too big for my 720 square foot house. I had the compressor and outdoor components exchanged for 2 ton components within two weeks. The humidity is always in the upper fifties so it never feels good. Another sign it's too big. Not surprisingly, the blower motor went out at 12 months. I was lead to believe it was a manufacturing problem. Doesn't take a genious to figure out a system turning off and on too often will also cause wear and tear. Which leads us back to the original question....how short is too short? It was hot here in Chicago yesterday, 85, and my newly repaired A/C was on 7 minutes and off 7 minutes which I felt was too short. Still at a loss given the info here. It was hot, am I wrong in thinking it was too short? BTW, I realize insulation, window and door leaks must factor in. Four years ago I had 8 inches of insulation blown the attic. My old two ton A/C never had such short cycles, not even with 4 inches of insulation. I understand on a hot day 10 minutes on and 10 minutes off or three cycles an hour could be appropriate from info I got elsewhere. Anyone agree? Comments? I can't replace worn out parts every year.



I've a question for you. The size of your AC unit seems to be too big for your small well insulated house, did the HVAC contractor do any calculations or take into account the energy saving measures you have taken? I've a few more questions I'm formulating since one of the things I did when I was still working was HVAC system installation and repair. ヽ(ヅ)ノ

[8~{} Uncle AC Monster



I saw her say that they put in a new 2.5 ton, then swapped it out two
weeks later for 2 ton. But I missed that the place is only 750 sq ft!
That's like three 20 x 12 rooms. We don't know the rest of the situation,
but I agree, it sure seems oversized, still, to me. 2.5 tons is 30K BTUs.
It's like having a 10K BTU unit in each room. Would you buy a 10K
unit for that size room? Even more remarkable is that
they had a 2.5 in there, knew that was too big, but then only went down
to 2.0? It's probably useable with that size if she gets the short
cycling fixed, but it's most likely not optimum either.

What was in there before they put the new 2.5 ton in? What was the
experience with the old unit?



I have a two level house. I don't have central but use three window
shakers. The lower level is 1000 feet but the utility/laundry area is
closed off. The remaining portion is comfy with an 8,000 btu unit. The
upstairs is also 1000 feet. One end has 10,000 btu and our bedroom has
6000. So, I'm doing a larger area with just over a ton.

Insulation, window area climate, etc has to be considered but I think
she is still oversized ay at least a half ton, maybe more.
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