American Locomotive
Well-known member
I agree with Yankee farmer's opinion that something seems odd about the graphs. Is this a single or two stage cooling system?
First, does your thermostat have adjustable hysteresis? It seems it like's set very small - like 0.5°F +/-. I would try +/- 1 degree so the system runs longer. Also, why are there times in the middle of the night where the fan is running, but the cooling is not? I feel like your thermostat must have some kind of "adaptive" hysteresis or something that's not actually helping anything.
However, the biggest problem seems to be that your house either has massive air leaks or poorly functional insulation. The temperature starts rising quickly the moment the system shuts down, even at 4AM when the outdoor temp is only a degree higher than the setpoint. It's absolutely absurd that your system is still running at or over 50% duty cycle when the outdoor temperature is 74 and the interior set point is 73.
I would start by verifying that you actually have 18" of blown-in insulation in the attic. Odds are, you don't. It's very common for builders to skimp on this. They'll build it up to 18" around the attic access, and then have 2" everywhere else. They do this, because for the most part someone will just pop their head up, stick a ruler in the insulation right there near the access and will not investigate any further.
Finally, there is no such thing as a "starter home". That's just a word they made up in the past couple of decades to encourage people to purchase the large 2500 sq-ft monstrosities popping up everywhere. You have big homes, and small homes. You have poorly built homes, and well constructed ones. You have cheap homes, and expensive homes. There is no correlation between any of those things. For the most part, the new, large, expensive homes are often poorly built with poorly installed insulation.
First, does your thermostat have adjustable hysteresis? It seems it like's set very small - like 0.5°F +/-. I would try +/- 1 degree so the system runs longer. Also, why are there times in the middle of the night where the fan is running, but the cooling is not? I feel like your thermostat must have some kind of "adaptive" hysteresis or something that's not actually helping anything.
However, the biggest problem seems to be that your house either has massive air leaks or poorly functional insulation. The temperature starts rising quickly the moment the system shuts down, even at 4AM when the outdoor temp is only a degree higher than the setpoint. It's absolutely absurd that your system is still running at or over 50% duty cycle when the outdoor temperature is 74 and the interior set point is 73.
I would start by verifying that you actually have 18" of blown-in insulation in the attic. Odds are, you don't. It's very common for builders to skimp on this. They'll build it up to 18" around the attic access, and then have 2" everywhere else. They do this, because for the most part someone will just pop their head up, stick a ruler in the insulation right there near the access and will not investigate any further.
Finally, there is no such thing as a "starter home". That's just a word they made up in the past couple of decades to encourage people to purchase the large 2500 sq-ft monstrosities popping up everywhere. You have big homes, and small homes. You have poorly built homes, and well constructed ones. You have cheap homes, and expensive homes. There is no correlation between any of those things. For the most part, the new, large, expensive homes are often poorly built with poorly installed insulation.
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