[Greenbuilding] [BULK] Re: Question about Air Conditioning

Wed Oct 24 13:36:59 EDT 2007

Definitely insulate first.  Look into insulating the attic too.  The
difference between an uninsulated 2X4 wall and a cellulose 2X4 wall is
dramatic, and I have experienced this myself.  I would put off the air
conditioning project until you've gone through a full summer, unless
your location is somewhere like Phoenix where AC is not optional.  You
may find out that good insulation, esp. in the attic, and some window
fans will get you through just fine.  I've lived many summers in
Missouri in a re-insulated farmhouse, without AC, and didn't really mind
it that much.  I always slept in front of a window fan or on the porch
on the hottest days.  

3 tons sounds like a lot for this size house.  Don't let those HVAC
contractors oversize your air conditioner, it won't dehumidify properly
and it runs less efficiently.  

If you do put in AC, think about using a heat pump and supplementing
your heat with it.  I didn't catch what kind of heat you have but I
assume it is probably forced air furnace.  

Lawrence Lile, PE, LEED AP
Project Solutions Engineering

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Kathy
Cochran
Sent: Wednesday, October 24, 2007 9:43 AM
To: 'Keith Winston'; 'Greenbuilder list'
Subject: [BULK] Re: [Greenbuilding] Question about Air Conditioning
Importance: Low

Thanks for your responses.  I will try to provide more information so I
can
get some more answers.  I appreciate the formula for understanding
"SEER"
ratings. The house is 1550 sq ft.  Kind of a basic "H" shape, with the
living room/dining room on the south, and the bedroom(2)/bathroom(2)wing
on
the north, with the center section being the kitchen / entry way.  Built
in
1940 out of 2x4 (original full-dimension 2x4's) construction, plaster
inside
and stucco outside, wood floors, and NO INSULATION at all, on a raised
foundation.  The plan is to have cellulose blown in (from the inside, to
eliminate damage to the stucco finish outside. I am wanting to insulate
MORE
not less, but I know the narrow walls will limit me somewhat in this
endeavor.  However, the attic and under the house allow for quite a bit
of
insulation, which will be put in.   

The house is in San Andreas, (Calaveras County) at 1000 ft elevation.  I
can't really estimate my cooling bills, because I haven't ever lived in
this
house with any cooling system, as the house was given to me to move. I
never
lived in it before I had it moved here.  Actually, it used to have a
swamp
cooler under a window in the living room, and it created so much water
damage that I pulled out both of the windows and am currently installing
low-e French Doors to the south, that eventually will have a deck to the
view.

There used to be a brick fireplace between the 2 old windows in the
living
room, but moving the house necessitated eliminating the fireplace, so
now
the plan is to install a wood stove or a propane stove between the
French
Doors.  

Thanks in advance for more responses.  Kathy

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Keith
Winston
Sent: Tuesday, October 23, 2007 10:58 PM
To: Greenbuilder list
Subject: Re: [Greenbuilding] Question about Air Conditioning

Hi Kathy: you say "Summers can easily get to be 110F". Where exactly in 
N. CA are you? Those are very unusually high temperatures for N. CA., I 
think. We can find what your actual design temps are when we know where 
you are located.

Your questions are only about cooling. You are in a heating dominated 
climate I THINK. If you do little cooling, then a higher efficiency unit

makes less sense. In any case, always attend to insulation and air 
tightness first and foremost, and possibly consider (if you've been 
successful at air tightness, especially) mechanical ventilation (an HRV 
or ERV).

All that said, SEER is a linear measure of efficiency, so a 17 SEER unit

will use 13/17's as much energy as a 13 SEER unit. If you can estimate 
your cooling bills, you can figure out the payback period of the higher 
efficiency unit.

What is the house like? How big? How many rooms? Have you considered a 
mini-split system? Might not be appropriate, or might...

Keith

Kathy Cochran wrote:
> Hello, I am putting an old house built in 1940 back together.  I moved
it
> from 20 miles down the road (in 4 pieces).  I am in Northern
California,
> where summers can easily get to be 110 degrees and winters down to 20
> degrees.  I am getting bids for Central heat (propane) and air, and
have
> some questions about air conditioning.  I can get a 3 Ton high
efficiency
> furnace + installation, with digital programmable thermostat for
$4500,
plus
> the A/C.  
>
> I have been quoted $1515 more for a 13 seer condensing unit, $2600 for
a
15
> seer unit, and $3,086 for a 17 seer AC unit.  Is the 13 seer enough?
Is
> the 17 seer overkill?  I would appreciate any comments any of you
might
> have.
>
> Regards,
>
> Kathy Cochran
> Kathys_old_house at goldrush.com
>
> -----Original Message-----
> From: greenbuilding-bounces at listserv.repp.org
> [mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Racheli
Gai
> Sent: Wednesday, October 03, 2007 7:52 AM
> To: Greenbuilder list
> Subject: [Greenbuilding] Advice on heating
> Tucson______________________________________________
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