My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening.

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.

Thanks,

wrote:

My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening. (That is okay!)

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.
Thanks,


Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell

--

What is the most Affordable Path to the "Human Comfort Zone" Goal?
http://www.udarrell.com/air-conditio...tent-heat.html

On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:

wrote:

My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening. (That is okay!)

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.
Thanks,


Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell

Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?

JimL wrote:
On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:

Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell

Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

On 20 Jun 2005 18:46:22 -0700, "RicodJour"
wrote:

JimL wrote:
On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:

Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell

Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

So?

You satisfy his demands or you take a long hard look at yourself and
ask if you maybe ought to get out of the way for those that can.

And what the hell about 'outside its design criteria'???? The
number one design criteria is - "Make the customer happy ie.. 68
degrees on a 105 degree day". What about that don't you understand?

wrote:
My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening.

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.

Thanks,

You seem to have the right idea. I will make just a couple of general
observations for thought.

Most of the time the system will be designed to handle a high
temperature, but not the highest likely to be encountered. So it would not
be unusual for a system not to be able to held 72º on the hottest day of
the year.

I would expect most well designed units to run close to full time on
very hot days.

The real problem comes up when someone has it turned off or set to 85º
on a very hot day and expects it to get the temp down to 72º in 45
minutes.

Most people are comfortable with a slightly higher temperature on very
hot days than they would be on a less hot day. This is more so in humid
areas as the humidity difference becomes greater.

If you are considering installing a new unit, do talk to the contractor
about your concerns. Don't totally ignore the humidity issue, even in a dry
climate. Your local professional should have a good feel for the local
conditions that we really don't have.

--
Joseph Meehan

Dia duit

"Joseph Meehan" wrote

wrote:
My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

If you are considering installing a new unit, do talk to the
contractor
about your concerns. Don't totally ignore the humidity issue, even in a
dry
climate. Your local professional should have a good feel for the local
conditions that we really don't have.

Joe,

You missed the part that this is a new unit.

PHIL wrote:

JimL wrote:

On 20 Jun 2005 18:46:22 -0700, "RicodJour"
wrote:


JimL wrote:

On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:

Why would they want to set the TH at 72? As the temperature goes
down the relative humidity tends to edge upward; i.e., cold and
clammy. If you provide adequate air circulation in that dry climate
you should be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they
want to freeze and pay the costly utility bill.
- udarrell

Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

So?

You satisfy his demands or you take a long hard look at yourself and
ask if you maybe ought to get out of the way for those that can.

And what the hell about 'outside its design criteria'???? The
number one design criteria is - "Make the customer happy ie.. 68
degrees on a 105 degree day". What about that don't you understand?


JimL - first thing you need to do is chill out dude. Pun intended.

My understanding from when I had a new furnace installed a couple years
ago and was discussing the option of also getting central air hooked up at
the same time was this - Household central air units are designed to
provide a max differential air temperature of 15 degrees.

If it's 85 degrees outside, the a/c can reduce that to 70.
If it's 100, then the best it can do is drop the temp to 85.

So then if the outside temp is 90, trying to cool the house to 70 is beyond
the units capability & "Outside its design criteria."

20

hvacrmedic

Yep, it's nearly new -- come to think of it, I may have had it
installed in Aug 03. So I got about 1.5 mos. of use the 1st summer
and all of last summer. But I've always questioned how much it should
run on the warmer, 90+, days.

It's a 3 ton unit - both outside and in.


On Tue, 21 Jun 2005 02:13:27 GMT, "Grub Hoe" wrote:


"Joseph Meehan" wrote

wrote:
My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

If you are considering installing a new unit, do talk to the
contractor
about your concerns. Don't totally ignore the humidity issue, even in a
dry
climate. Your local professional should have a good feel for the local
conditions that we really don't have.

Joe,

You missed the part that this is a new unit.

JimL wrote:
On 20 Jun 2005 18:46:22 -0700, "RicodJour"
wrote:
I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

So?

You satisfy his demands or you take a long hard look at yourself and
ask if you maybe ought to get out of the way for those that can.

And what the hell about 'outside its design criteria'???? The
number one design criteria is - "Make the customer happy ie.. 68
degrees on a 105 degree day". What about that don't you understand?

I understand that you must have a horrible home life to talk to people
the way you do.

The HVAC system is an inanimate object and doesn't care what you want
or whether you are happy. It does what it can.

An HVAC system is designed taking into account many factors, including
the construction, area of windows, etc. The design criteria include
what the desired ambient temperature is under the specified design
temperature and humidity. Then the system is installed to meet those
demands. If the temperature or humidity exceed the design
specifications the sytem will not increase its capacity magically.
Just because you or your brother-in-law "demands" that the system
operate beyond its intended operating range, doesn't mean that it will.

R

more likely that your home is "under-insulated"



wrote in message
news
My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening.

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.

Thanks,

Joseph Meehan wrote:

The real problem comes up when someone has it turned off or set to 85º
on a very hot day and expects it to get the temp down to 72º in 45
minutes.

Misters might help in this case, cooling the house as water evaporates and
raising the latent load and heat transfer rate at the evaporator coil,
esp if the house is airtight and hot and dry to begin with.

Nick

cowboy wrote:
more likely that your home is "under-insulated"


I would tend to say all homes are under-insulated. :-)

In this case with a newish unit taking a good look at insulation and
possible upgrades may be a very good approach, cheaper that hardware.


--
Joseph Meehan

Dia duit

RicodJour wrote:
JimL wrote:

On 20 Jun 2005 18:46:22 -0700, "RicodJour"
wrote:

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

So?

You satisfy his demands or you take a long hard look at yourself and
ask if you maybe ought to get out of the way for those that can.

And what the hell about 'outside its design criteria'???? The
number one design criteria is - "Make the customer happy ie.. 68
degrees on a 105 degree day". What about that don't you understand?


I understand that you must have a horrible home life to talk to people
the way you do.

The HVAC system is an inanimate object and doesn't care what you want
or whether you are happy. It does what it can.

An HVAC system is designed taking into account many factors, including
the construction, area of windows, etc. The design criteria include
what the desired ambient temperature is under the specified design
temperature and humidity. Then the system is installed to meet those
demands. If the temperature or humidity exceed the design
specifications the sytem will not increase its capacity magically.
Just because you or your brother-in-law "demands" that the system
operate beyond its intended operating range, doesn't mean that it will.

R

I think the OP asked though if his unit was undersized and did not get
any response to that question. Therefore to claim that the response was
actually addressing the mechanics of the question if not the spirit of
the question is still incorrect.

His concern was that his system runs continuously right? Was not addressed.

--
Respectfully,


CL Gilbert

My understanding from when I had a new furnace installed a couple years
ago and was discussing the option of also getting central air hooked up at
the same time was this - Household central air units are designed to
provide a max differential air temperature of 15 degrees.

If it's 85 degrees outside, the a/c can reduce that to 70.
If it's 100, then the best it can do is drop the temp to 85

This is wrong. I live in Arizona where it was about 112 degrees yesterday.
That would mean the temp in my house would be 97 degrees----We keep it at 78
and our A/C unit has no problem at all. I have customers that keep their
homes around 68 degrees and their units cycle just fine. A few years ago
when it was 122 outside my unit didn't cycle off much.

I think the installer may have been referring to the temp split a unit
operates on. The air coming out of the vents is about 15 to 20 degrees
cooler than the air going into your return vent. This does not mean the the
unit will only cool 15 to 20 degrees below the outside temp.

AZCAIG

www.arizonavintagetrailers.com

CL (dnoyeB) Gilbert wrote:
I think the OP asked though if his unit was undersized and did not get
any response to that question. Therefore to claim that the response was
actually addressing the mechanics of the question if not the spirit of
the question is still incorrect.

His concern was that his system runs continuously right? Was not addressed.

Feel free to chip in if you feel there's an omission.

My original response wasn't to the OP, but to the poster that felt
compelled to jump all over someone who pointed out some of the salient
facts about relative humidity.

If the system runs continuously on hotter than usual days, that is not
unusual. If the system can't bring the house to a comfortable level,
that is unacceptable. If the occupant wants 58 degrees (that's
refrigeration, not air conditioning) on a 115 degree day, that's
unusual but can be provided if the system is designed for it.

I worked for the construction manager when the South Street Seaport
Experience was being built in NYC. It's a multi-media theater that
depicted the life of whalers and such. Part of the experience was to
drop the temperature 20 degrees in about five minutes to indicate the
winter conditions that whalers would have to endure. On a hot summer
day, sitting there eating popcorn, I envied those whalers!

R

On Mon, 20 Jun 2005 21:01:10 -0500, JimL wrote:

On 20 Jun 2005 18:46:22 -0700, "RicodJour"
wrote:

JimL wrote:
On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:

Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell

Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria.

R

So?

You satisfy his demands or you take a long hard look at yourself and
ask if you maybe ought to get out of the way for those that can.

And what the hell about 'outside its design criteria'???? The
number one design criteria is - "Make the customer happy ie.. 68
degrees on a 105 degree day". What about that don't you understand?

Hey guys,

The only important design criteria comes directly from the customer
and only from the customer.

It does not come from some moron in the news group talking about
ideal humidty control or such crap. It comes from the customer who
says he wants a system that provides 68 degrees on every hot day in
July.

Now let me give you a clue so you are not completely clueless.

My brother-in-law did NOT say that he wanted 68 degrees and then
attach a condition that it had to be a specific size unit or that it
had to be efficient or that it must be limited to only one unit Half
the houses in my subdivision have 2 units. So don't be a moron. Add
units and tons until you satisfy the customer. I just don't
understand you guys. How simple is that solution?

JimL wrote:

On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:



wrote:



My AC when it's 90 out will nearly run continuously. I'm just curious
if that is normal or if I have been undersized by the contractor
(installed a year ago).

I live in Colorado - dry climate.
We get a lot of direct sun.
The ranch has 1800 sq ft on the main level and a below grade bsmt of
the same size. Part of bsmt is finished, but we do not occupy it
often.

Mid June - end of August can have 90 degree days; seems like most days
are 85-95.

We set the thermo at 76 degrees. But if it's 90 outside and I try to
set below 76, it will never make it down until evening. (That is okay!)

For mid 80s days, it's fine (remember we set our thermo at 76 though).

I'm concerned that a) the HVAC contractor has undersized my AC unit
and b) if a new owner preferred 72, it could not be held during our
summers.

I realize it's best not to oversize the unit, but with a dry climate
to begin with, removing humidity is not much of an issue.
Thanks,




Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell



Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?


Yes, I am a piece of work.
Many factors enter into the "Human Comfort Zone Conditions;" a 72-F with
little air movement and a higher %RH will normally not be as comfortable
as 76-F with more air movement and a lower %RH. These findings are the
result of a lot of testing resulting in the "Human Comfort Zone Chart."

I am NOT dictating anything everyone is welcome to oversize and run
their A/C down to 68-F if they want; I will sell them and install
whatever they want. However, I will tell them that when it is oversized
and operated at around a 70-F level, the seer rating goes out the window!

They are rated at a much higher conditioned space temperature. The
evaporator will not be adequately heatloaded at low temperatures and the
low airflow required to get the humidity down in the comfort zone at
those temps. (Coil Freeze-ups on the way.)
I will also let them know how inefficient and costly it will be to run
the oversized inefficient system.

I like R's Response to your comments:

I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria. R

Why should we be concerned about the next guy that lives in our home;
let them change things to suit their varied individual tastes.
- udarrell

--

What is the most Affordable Path to the "Human Comfort Zone" Goal?
http://www.udarrell.com/air-conditio...tent-heat.html

cm wrote:

My understanding from when I had a new furnace installed a couple years


ago and was discussing the option of also getting central air hooked up at
the same time was this - Household central air units are designed to
provide a max differential air temperature of 15 degrees.

If it's 85 degrees outside, the a/c can reduce that to 70.
If it's 100, then the best it can do is drop the temp to 85



This is wrong. I live in Arizona where it was about 112 degrees yesterday.
That would mean the temp in my house would be 97 degrees----We keep it at 78
and our A/C unit has no problem at all. I have customers that keep their
homes around 68 degrees and their units cycle just fine. A few years ago
when it was 122 outside my unit didn't cycle off much.

I think the installer may have been referring to the temp split a unit
operates on. The air coming out of the vents is about 15 to 20 degrees
cooler than the air going into your return vent. This does not mean the the
unit will only cool 15 to 20 degrees below the outside temp.

AZCAIG

www.arizonavintagetrailers.com




What they used to say was that if your A/C could always keep the room
temps 15 and later they said, 20 degrees below the outdoor ambient the
occupants would feel comfortable. That goes out the window if you are in
a high humidity climate and the A/C won't get the humidity level down to
around 50%.

Most of Arizona is a very dry climate; therefore, the A/C is able to
handle the sensible heatload rather handily. The equation is much
different in a high humidity climate.

You are not wrong in what you say. Your comfort level will depend
largely on where the %RH level is, and also on the air movement in your
home.

The more you reduce the temperature of air, the humidity percent will
go up proportionately; therefore it has to spend extra runtime wringing
out that humidity from the extra degrees of colder air.

Design split between outdoor and indoor conditions --varies due to many
variable factors. However, the Btu/hr and SEER ratings are taken at only
one set of conditions. Changing any factors from the Design Conditions
will change up or down Btu/hr and SEER. - udarrell

--

What is the most Affordable Path to the "Human Comfort Zone" Goal?
http://www.udarrell.com/air-conditio...tent-heat.html

JimL wrote:

The only important design criteria comes directly from the customer
and only from the customer.

It does not come from some moron in the news group talking about
ideal humidty control or such crap. It comes from the customer who
says he wants a system that provides 68 degrees on every hot day in
July.

Now let me give you a clue so you are not completely clueless.

My brother-in-law did NOT say that he wanted 68 degrees and then
attach a condition that it had to be a specific size unit or that it
had to be efficient or that it must be limited to only one unit Half
the houses in my subdivision have 2 units. So don't be a moron. Add
units and tons until you satisfy the customer. I just don't
understand you guys. How simple is that solution?

While I always enjoy hearing tales about your brother-in-law and look
forward to reading about him, I don't see what he has to do with the
OP.

We have no idea how the OP's system was designed, whether the Manual
J's were done or the cooling load just guessed at, whether the OP went
with the lowest bidder, etc. The OP is not happy, and I agree that he
should be happy in his own house. Whether the contractor undersized
the system (which sounds like a definite possibilty) due to a mistake,
ineptness or because the OP asked specifically for a 3-ton (or
whatever) system, we don't know.

Obviously if the OP has a problem with his system and is not happy he
should contact the contractor and have him take a look at the system to
see if it's operating as it should. Maybe there's a leak, clogged
filters - many things could affect the system's ability to cool. If
nothing is amiss, then the OP can discuss his dissatisfaction with the
system's performance and can discuss what can be done and on whose
dollar.

Your categorically stating that a contractor has to "satisfy the
customer" at all costs is naive and inflammatory. But I think you
already know that.

R

RicodJour wrote:

JimL wrote:


On Mon, 20 Jun 2005 18:56:04 -0500, udarrell
wrote:


Why would they want to set the TH at 72? As the temperature goes down
the relative humidity tends to edge upward; i.e., cold and clammy.
If you provide adequate air circulation in that dry climate you should
be very comfortable at 77 to 79-F.
It appears to be sized right. What tonnage is it.
Check out the Human Comfort Zone. They can add room A/Cs if they want
to freeze and pay the costly utility bill.
- udarrell


Boy, you are a piece of work, udarrell -
Telling the whole world what temperature they are comfortable with.

My brother-in-law just might accept 68 degrees on the high side but
he usually likes it lower. Ever hear the terms about satisfying the
customer or what the customer wants or the customer is always right?



I didn't think he was dictating thermostat settings, but questioning
the logic. It's a question of the system design. When a system is
specified design temperatures and humidities are provided. Someone who
wants 68 degrees is asking a system to perform outside its design
criteria. R


I just discovered that he has a 3-ton outdoor and indoor air handler and
coil system.
If you are cooling and additional 1800-sq. ft. of basement that changes
the equation!
Have your home checked and see what cooling Btu/hr it calls for; some
utility companies will do it for you!

Yes, Colorado is Very Dry! Design at Durango Design is 87-db and 59-wb
that charts to only around 20% RH.
Denver at the high altitude is worse: Design is 91-db and 59-wb; it's
literally off the charts.

A well insulated 1800-sq. ft. Ranch style home in that dry a climate
ought to be easily handled by a 3-ton system.
Here in a rather comparatively humid SW WI (Madison 88-db and 73-wb for
a 49% RH) we have 2400-sq. ft homes being nicely handled by 2-ton systems.

How good are the techs that check your system?
I believe there might be room for improvement; that merely an educated
opinion as I don''t have any of the required relevant facts.
Everything might be okay! During the hottest days it should run most of
the time.
- udarrell

--

What is the most Affordable Path to the "Human Comfort Zone" Goal?
http://www.udarrell.com/air-conditio...tent-heat.html

You need to first ask yourself was the system working fine after they
installed it or it just acting funny now???

I had a somewhat similar problem.

Last year I purchased a rheem high eff. central air system for
my home. At first it worked pretty good. When the temps outside
started to heat up the system wasnt performing well at all.

I took a temp reading at a few of the vents and noticed that it was
only a 10 degree difference than the outside temp, oh no.
(sort of explains why the system was on all the time and not really
cooling the home)

I called up the installer and they measured the temp too. It was off.

Turns out there wasnt enough freon in the system in the first place.
System ran day-n-night and couldnt keep up. They charged the system
up and it was working great for the rest of the year.

This spring on the first warm day I decided to make sure the system
was ok. Turns out the compressor wasnt turning over. I went through
troubleshooting and found that the low pressure switch was tripped.
I reset it and that didnt help. I called the installer and they found
that
there was NO freon in the system again. I almost went nutz (not in
front
of the tech though) Anywho... they did a leak check and found a
pinhole leak in the system. They charged it up again and all is
working
well again.

So far so good.

My understanding from when I had a new furnace installed a couple years
ago and was discussing the option of also getting central air hooked up
at
the same time was this - Household central air units are designed to
provide a max differential air temperature of 15 degrees.

If it's 85 degrees outside, the a/c can reduce that to 70.
If it's 100, then the best it can do is drop the temp to 85.

This is a crock. We commonly had 108 oF days in AZ and the ac had no
problem keeping the house at 76
A 32 degree differential.

I live in a 2000 square foot house in Hot, Humid Myrtle Beach South
Carolina. I have a 2 ton heat pump with 4 KW strip heat. It does just
fine.

The proper size for your house depends on YOUR house, climate,
insulation, construction, glass area and direction and type, duct
leakage, etc. It is possible that it is undersized but that can not be
determined from here.

The temperature difference between the outside and inside is determined
by your comfort level and your climate. Here in Myrtle Beach, we use
20 Degrees. IN death Valley you would Size for a lot more. The units
are rated for ARI conditions. You should size them based on Manual J
conditions. Your installing contractor should have done that. If you
are not comfortable, he should make it right under warranty.

Did he seal your ducts?

Did he measure air flow?

Did he do a capacity check?

These are questions I would have for the installing contractor.


Stretch