Professionals call this temperature.
Ac unit temperature drop attic duct.
Well there s not a universal fixed temperature your ac should always be blowing.
As long as the building has not reached its thermostat s set point.
Put another into a supply duct as close to the unit as possible.
Although both the attic floor and the ductwork are insulated ted recognizes the situation isn t ideal.
Then allow the ac unit to run at least 15 minutes.
Summer hasn t even arrived he notes in a post at gba s q a forum and when the temperature outside climbs to more than 95 f the temperature in the attic tops 120 f.
Going up into an attic and seeing ductwork running every which way is not an uncommon sight.
If you ve studied heat transfer at all you may recall that the rate at which heat moves from a warmer to a cooler body depends on the temperature difference which we abbreviate as δt.
So even though there s no single ideal temperature you do want a 16 22 f difference from the supply air and return air.
Attic hvac systems save space.
An attic can get up to about 130 f in the summer and the conditioned air entering the ducts is about 55 f or so.
Put one into a return duct closest to the unit as possible.
There too unless the supply duct is long uninsulated running in a hot space such as an attic the air temperature at the supply register should be around 55 degrees.
Instructions input information may generally be be obtained from design documents or field measurements.
So why put an hvac system up in the attic at all.
Most updated central air conditioned homes have a new air conditioner split system meaning the ac is broken up into parts.
Ted also has inherited a powered attic ventilator.
You should expect a 15 to 20 degree temperature differential from the air temp going in and the air temp coming out after the unit has been running a period of time.
In addition to making the unit hard to get to for service high attic heat can trigger the high pressure limit switch turning your condenser off.
That has kept the ventilator working but ted surmises the high temperatures are reducing the efficiency of his air conditioning equipment.
Calculates the temperature change of air flowing in a duct reference.
I suggest you use 2 accurate thermometers.
Place the thermometer on a vent and leave it in.
The temperature your ac puts out is relative to the temperature you set on your thermostat.
The result is that air your furnace or ac has already treated is losing energy back into the attic.
It also means that the air in those ducts is continually exposed to the ambient temperature in the attic.
2009 ashrae hof chapter 4 equation 48 pg 4 21 this calculator estimates the temperature drop or rise of air flowing in a duct.
Well mainly it s a way to save space.
The system should be blowing air that is noticeably cooler than the building s air.
