# Thread: Is new ac running to long?

1. Let's look at it with some basic logic -

"Runs 2 hours - then is only off for a few minutes."

That sounds like tremendous heat-gain: The unit takes 2 hours to lower the house temperature one degree or less - the thermostat's differential - and as soon as the AC shuts off the continually incoming heat almost immediately triggers the AC back on again. Where is all that heat coming from?

Is the roof black or otherwise dark?
Is there any tree or other external shading?
Is there any insulation in the attic?
If so; how much?
Was there an attic exhaust fan?
If so; does it work?
Are there inlet vents to the attic space?
In the middle of the afternoon are the interior ceilings warm to the touch?
In the middle of the afternoon are interior surfaces of the west walls of the house warm to the touch?
Thermopane windows?
Good weather sealing?

And this is all when it's only 85º outside? Let's forget the AC for the moment - what is going on with the building envelope?

PHM
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Originally Posted by ajlocke
1500 sq ft raised ranch built in 2001. Just had a 3 ton rheem ac put in, we just moved in so I don't know what "normal " run time is for this home. Ac runs for about 1 1/2 to 2 hours reaches/maintains set temp shuts off then cycles back on within minutes. Thermostat temp does not go up before it cycles back on. Could it be the thermostat? It is located in the hallway. I have a room thermostat that reads a degree lower than wall tstat when running and quickly goes up a degree when unit cycles off. Outside temp 85,dew point 65 humidity 53%. It's 2 hour run time to long? Tstat set to 76 stays at 76 the whole time it's running,even when it first turns on (room thermometer says 75)

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Originally Posted by Poodle Head Mikey
Let's look at it with some basic logic -

"Runs 2 hours - then is only off for a few minutes."

That sounds like tremendous heat-gain: The unit takes 2 hours to lower the house temperature one degree or less - the thermostat's differential - and as soon as the AC shuts off the continually incoming heat almost immediately triggers the AC back on again. Where is all that heat coming from?

Is the roof black or otherwise dark?
Is there any tree or other external shading?
Is there any insulation in the attic?
If so; how much?
Was there an attic exhaust fan?
If so; does it work?
Are there inlet vents to the attic space?
In the middle of the afternoon are the interior ceilings warm to the touch?
In the middle of the afternoon are interior surfaces of the west walls of the house warm to the touch?
Thermopane windows?
Good weather sealing?

And this is all when it's only 85º outside? Let's forget the AC for the moment - what is going on with the building envelope?

PHM
-------
Dark roof,yes. Was told at inspection that there is alot of insulation in attic. No attic exhaust fan as far as I know. Inlet vents yes. I have not noticed walls or ceiling being warm. We have a small tree in the front and one in back neither provide much shade. Doubt these are thermopane windows. We are having someone come out in a few weeks asses the "energy" efficiency of the home.

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Location
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## Grinding out the Grid

WE NOW KNOW the residence location within 44,612,474 Acres.

37.0'N to 39.5'N

38.3' +/- 1.3'N … 93.3'F / 75.9'F DB/ WB ASHRAE 1% design point

NOT Too many Annual Cooling Degree Days (CDD) < 1,700
HDD < 5,000

-------
Energy Audit overview can normally be determined from
electricity usage for EACH of the last 24 months
_________________

Calc is now within ~ 25% accuracy
______________

I know my A/C system does Not run too much.
It's always < 15 hours / day.
_________------____

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Originally Posted by ajlocke
Missouri and that was outside rh
38.5385950638 ' + / -

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Originally Posted by dan sw fl
38.5385950638 ' + / -
everything you said is foreign to me,update is 93 today with a heat index of 100,ac has not shutoff and staying a degree above tstat temp.

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