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HVAC efficiency - upgrade was worth it

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Brad Johnson:
This month marks the second year since I upgraded my HVAC system, installed a programmable thermostat, and added eight inches of blown-in insulation to the attic of my 25 year old home. The total energy savings, thus far, averages 37%. Some months, especially in summer, the savings approaches 50%.

That's right, the upgrade cut my total annualized utility bills by over a third even though I am keeping it slighly cooler during the summer. If the savings remains constant it will offset 100% of the upgrade cost in just under 7 years.

The system is rated at 12 SEER, but my AC-expert friend who installed it is like me - one of those guys who studies things to death (probably why we get along so well). The system is all Trane, but the air handler and inside coil are not the units usually spec'd as companions to the compressor. He did a mix/match setup using a bunch of energy tables and air movement calcs. According to his estimates my system should be functioning at just over 14 SEER. Based on my energy savings I have no reason to doubt him.

In case you were wondering, the electric bill during the 05/15-06/15 billing cycle for my 1640 sq ft home was ninety bucks ($90) vs $170 for the same time two years ago. That's with daily highs no lower than than 95 and almost two full weeks of 100 deg plus days. I was also keeping the inside temp a cool 75 during the day and cooler 72 at night.

Not bad. Not bad at all.

Brad

Leatherneck:
COOL!





(I had to say it)

TC

K Frame:
Every year I tell myself that I'm finally going to add more insulation to the attic.

Every year I put it off.

I just need to get the rafter chutes in place and then find someone to turn the blower on and off while I fill the attic.

CHRIS! We have a job to do!

thebaldguy:
We replaced our old furnace (50% efficient) with a 92% model and added a high efficiency central air system a 18 months ago. We think it made a pretty big difference in gas/electric bills. Our a/c is on a saver switch, where the electric company will shut off the central air 15 minutes an hour during high use periods. They give a nice discount for agreeing to the a/c switch.

cfabe:
What a timely topic, I was just going to post something similar.

So given the expertise here, I'd like some suggestions for my new house. The home is a 1951 1000 sqft 1.5 story with an unfinished upstairs. Current equipment is a 5 year old comfortmaker natural gas 80% furnace, and an old old Singer central air unit outside. Both seem to be operating properly. The house has about 3" of fiberglass bat insulation in the ceiling, and about half the roof also has 6" fiberglass in the roof rafters (the rest had fallen out, city violation, was removed before sale). There is no ridge vent or soffit vents, but the attic area has two windows in the gable ends. The walls probably have no insulation.

Clearly insulation is in order, but I'm planning to finish the upstairs in a few years, would I be best re-insulating the rafters that are missing, or blowing some in on the floor to fill the joists?

I'm considering the slow-rise polyurethane foam for the walls, but it's pricey, going to cost about $2500 in materials for my small house, at least from the one outfit I checked with. How does blown cellulose compare in price and efficency?

On the gable ends I have windows. A friend mentioned putting a window fan in one window to ventilate the attic on hot days, and that this would reduce a/c expenses considerably. Thougts on that?

What kind of efficency improvements have they made in a/c in the last say 30 years? I wonder how much I could save by upgrading compared to waiting until the current unit dies.

In this area (northeast ohio) we tend to have a lot of days in the summer (like today) where the temperature, espicially at night, isn't bad but the humidity is high. Right now I have my window open blowing cool, damp air onto me. I'd much rather it be dry air. Is there any solution for dehimidifiying outside air and then using it to ventilate a house? Maybe at a lower operating cost than normal a/c?

In all of this, I'm faced with the budget of a single guy making decent money, but moving into my first house and having lots of other expenses. So I'd really only want to put money into things where I'm really going to see some return.

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