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My house has an existing forced-air heating system and I'm looking at getting central AC added in a few weeks' time (indeed, I've booked contractors for estimates next week). An AC system would keep my house cool when it is hot outside.

...but what options are there for cooling a house when it's also cold outside (without running expensive AC)? I don't like having to manually open windows, so I was wondering if there was some kind of additional cooling system which sucks in cool air from outside and blows it through the forced-air ducts, thus cooling down the interior without needing to run AC.

...does such a system exist? Do AC systems do this anyway?

Dai
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4 Answers4

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There is an optional add-on part for HVAC systems called an economizer.

An HVAC economizer is a dampered vent designed to save energy and give the cooling system a break. Sensors within the economizer compare the outdoor temperature and humidity with that inside the building. –Google

When you call for cooling, the unit decides if it needs to run the AC or just open the economizer to pull in outside air.

Mazura
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You're looking for the V in HVAC (Ventilation). There are indeed systems that will pull in outdoor air, filter it, and supply it through the home. These systems would likely be in addition to any heating or cooling equipment, not as a part of them. To be specific, you're looking for a balanced ventilation system.

Talk to your local HVAC company, they should be able to recommend a system that will work with your existing equipment. They should also be able to provide you with an estimated cost of installing such a system.

Tester101
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The term you're looking for is "whole-house fan". It's a big fan that can blow outside air, inside. I have one in my house and they work very well for your use case. Be warned that whole-house fans are notoriously difficult to insulate and air-seal. When winter rolls around, the last thing you want is a huge hole in the side of your house through which frigid air can easily enter.

Furthermore, you'll have to open your windows. But this is unavoidable anytime you want to draw substantial quantities of outside air into your house; it has to escape somewhere. With the windows closed, the air will escape through random cracks in your house, but only so much can escape that way. To properly exhaust the volume of air you would need to push through your house to actually meaningfully drop the interior temperature (a lot; like 3000 CFM), you would need to punch a huge home in your wall somewhere--otherwise known as a window. :)

iLikeDirt
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I have had these systems installed on commercial applications. The system principal working method , Outside air is measured in temperature, i.e. the cooling system is calling for 74° and the exterior temperature is 63, two separate ventilation systems open, The forced air to supply your house with the cool air opens and the fan turns on. A second, exhaust system opens up to allow over pressure to release from your home. Essentially these are two VAV boxes one with forced air "supply" and one with Variable louvers. " exhaust" The controls are then integrated into your existing thermostat system. The controls are then integrated into your existing thermostat system

. I am getting ready to install one of the systems into my home, it will be makeshift due to the type of split system I already have but it is possible. If you explain to your HVAC contractor what you are after they probably could devise something for you as well.

Dax
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