[Greenbuilding] Question about Air Conditioning

[Keith Winston]

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
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