Air handler exchanging fresh air?

[hal1]

Wasn't sure how to title this.

I have a new house, and when the A/C is off, and the fan has stopped I heat a faint motor sound from up in the attic - most noticeable when standing under the return.

I sent a text to the superintendent of the newly built subdivision and asked if there is some type of ventilation fan that I am hearing. His answer...

"That's the Air Handler (in the attic) exchanging fresh air. The t-stat for that is in the laundry room above the door"

I do know about the t-stat - I was told to not use/touch/adjust it. I don't remember exactly what it was for, but it does sound familiar that it was to comtrol somehting like this or as a backup to shut down the system if it get too hot (not sure about that last part)

Does this make sense? Can someone explain it better? And, if it is the Air Handler exchanging fresh air, where is it exchanging to and from?

Phoenix. 110+ outside today

 

[Chuckster in NJ]

Go up into the attic and see what it is...... An exhaust recovery ventilator (ERV) will have four flex ducts running to it. This ERV is used to ventilate a "tight" home without removing all the heat or AC.
A fresh air intake that brings fresh air into the "tight" home will have one 6" or 8" duct running to it and will run to the return duct.
An attic fan is just a fan that ventilates the attic..... Usually on the roof or gable end of the house.
Please take a look and report back on what you find so we bpcan explain it to you.

 

[kwschumm]

Here in the Pacific NW it is common to have an exhaust fan somewhere that runs on a timer to pull interior air out of the house. There are then make-up air vents, often in the window frames, that allow fresh outside air to be drawn in. It's one way to make sure that interior air is kept fresh but it ***** from an energy conservation viewpoint. If that's what your system has it's pretty inexcusable in Phoenix to do it that way. Our house has that method but when the furnace gets replaced (it's near the end of its life) we'll install an ERV and remove the fan.

 

[hal1]

Mybe this additional info helps....

Here's the t-stat above my laundry room door. And a website link for the description. I'm just not sure exactly what it is controlling?

http://www.alpinehomeair.com/viewproduct.cfm?productid=453058719&displaytab=instructions_brochures



The TrueIAQ monitors and automatically adjusts operation of your whole-house humidifier, dehumidifier, ventilator, or bath fan.
Maintaining proper indoor humidity minimizes the potential for unhealthy airborne pollutants to grow. Having too little humidity can leave you vulnerable to infections and uncomfortable dry skin. Too much humidity creates ideal breeding grounds for mold, mildew and dust mites. Humidified air also feels warmer in the winter, and dry air feels cooler in the summer.
TrueIAQ can adjust humidity with or without dependency on HVAC equipment operation.
If you have both a humidifier and dehumidifier installed, the TrueIAQ can automatically change over to the appropriate equipment based on your comfort settings and the changing outdoor conditions.
TrueIAQ can also deliver fresh air with or without dependency on HVAC equipment operation. Today's building codes require homes to be built more tightly for energy efficiency,
but that tightness can also trap indoor air pollutants, such as cooking odors, cleaning agents, radon, and carbon dioxide/monoxide. TrueIAQ provides cost-effective ventilation in accordance to industry standards. In addition, the TrueIAQ can be programmed to deliver ventilation during set times of the day or night.

 

[justinjoyal]

That very much looks like a ERV/HRV control.

 

[LS6 Tommy]

X2 on the ERV/HRV or some sort of IAQ fan system.

Tommy