DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   HVAC (
-   -   How cool should it be inside the house? (

beer_geek 05-07-2007 06:52 AM

How cool should it be inside the house?
What is a reasonable delta between the inside and outside temperature? Say it's 95 degrees F; what temperature should I be able to achieve inside?

harleyrider 05-07-2007 07:36 AM

Depends more on the humdity, but if you can get 20 degrees your doing good.

beer_geek 05-08-2007 04:04 PM

That's all? Thanks.

pjpjpjpj 05-09-2007 11:50 AM

The temperature inside your house should be.... whatever you are comfortable with.

Typically AC systems are sized for an indoor temperature of 70F-75F. While "studies" have indicated that the typical comfort level for humans is 75F and 50% relative humidity, everyone is different. Seems like most guys I know want it between 69F and 72F, and most women want it between 73F and 77F (summer time, in cooling mode).

That being said, if you live in a humid location, you need to think about humidity; that is, when your AC unit runs, it also dehumidifies. If you live in a "leaky" house, in a very humid climate, and you set your AC for a higher temperature, you are likely letting the humidity levels in your house get fairly high and risking mold/mildew issues. Also, if you have an AC system that is oversized for your house, and you set it for a nice cold temperature, the system will cycle (turn on, cool the place down to that temperature, and then shut off) too quickly, and thus not run long enough to adequately extract enough humidity from the air. That can promote mold/mildew growth as well (and a "clammy" feel in the space).

Typical AC systems are designed for outdoor air temperatures that are a "worst-case" for the area in which you live - in most of America, a summer temperature between 90F-96F, and humidity in the 40-55% range. They are then sized such that the supply air temperature is somewhere in the ballpark of 55F. The target is to have a 75F space (thus, 20 degrees difference across your cooling coil, known as "delta-T"). This commonly varies within about 5 degrees (usually with the supply air temp being slightly higher and the room/return air temp being slightly lower), but the closer you can keep it to the 20F delta-T, the more efficiently your system will be running.

beer_geek 05-10-2007 12:44 PM

I would love for it to get down to 75F in the Summer. In the upstairs part of the house, I can set the thermostat to 70F and it won't get below 79F.

harleyrider 05-10-2007 03:22 PM

How tight is the house?

cibula11 05-10-2007 03:44 PM

It all depend on humidity as it was stated already. Yesterday in Iowa the temps were 84 and a little humid. We had the windows open in every room and it read 74 on the thermostat. Other days that are cloudy it may be even cooler. Upstairs is 5 degrees warmer on average.

beer_geek 05-10-2007 04:00 PM


Originally Posted by harleyrider (Post 44593)
How tight is the house?

Fairly tight. 1999 construction. Right now it's set to 70F and it's 79F up here. It's 75F downstairs. Outside temp is 86F. 37% Humidity.

mikemy6 05-13-2007 01:42 PM

Many houses are set up for the heated air specs. without taking the heavier air from the AC as a consideration. Im thinking you have no air handler in the attic and your coil sits on your heater. Try adjusting the dampers or vent openings.

All times are GMT -5. The time now is 11:29 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1