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?

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

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?

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

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

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.

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.

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

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,

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

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.

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