improve cooling to the bedroom

Page 2 of 2  

On 7/23/2010 7:53 AM, jamesgangnc wrote:

Even here in Alabamastan, a well insulated 2 story home can be cooled by a 2 ton AC unit, it's all about heat load. I have one customer who has a new home and the upstairs heat pump is larger than the downstairs unit, why? Because the upstairs has some very large windows that reach all the way to some very high ceilings.
TDD
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jul 23, 6:39 am, snipped-for-privacy@optonline.net wrote:

Its possible he requires a 5 ton system for his 1700 sq ft. if he lives in south Florida or southern Arizona and has little or no shade, alot of glass facing south, and minimal attic insulation. But hes going to need more than 7 supply registers to get the 2000 cfm out assuming `14x6 " registers (or smaller) . The return is also going to be a factor too as they most likely undersized that too. I see it all the time even in very expensive homes over $1 million . Its amazing what they get away with.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

1. Because the room size (load) might require more airflow than what one register can deliver . 2. Because the room may be configured to where a single register wont distribute the air well enough . 3. Because the heat gain of the room might require multiple registers to deliver enough conditioned air to satisfy it. 4. Because one register might be too noisy if youre trying to push too much cfm thru it . 5. Too be sure youre moving enough air over the cooling coil to prevent freezeup especially during low load on the system.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So that the system heats and cools evenly. I just took a quick count of my house. I have 22 outlet vents. That's in a house that's 3100 sq ft, 4.5 ton AC. Seems about right to me. So for a house of 1700 sq ft, I'd expect around 12, not 7. Several of my rooms have 3 registers each. Every house I've ever lived in, including small single story ranch, have had at least some rooms with more than one vent.
Having 5 tons of AC with 7 vents just ain't Kosher.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Return air configurations come in a variety of ways. 1. There is the ONE huge central return air grille often put in the second floor ceiling at the top of the stairs which is ducted back to the Air Handler. 2. There are TWO large return air grilles...one on the first floor ceiling and one on the second floor ceiling...both ducted. 3. A number of return air grilles placed high on the inside walls of both downstairs and upstairs and ducted back. 4. A return air grille in EACH room (except the bathroom) and ducted back. In order to know if the return air duct system was properly sized, youd have to have a knowledgeable professional come out to determine the size(s) and how much each return air duct can handle in cfm airflow. I can tell you this fairly accurate rule of thumb : The return air duct area feeding a 2000 cfm (5 ton a/c system) such as yours, requires One 18" dia. round duct or Two 14" dia. round ducts (or equivalent retangular ducts in sq. inch area) . Hope this gives you a bit more insight. In addition, you need to make sure your air filter(s) , cooling coil surface , blower wheel ...are all very clean in addition to the system being full on freon and working properly . Ideally, you should bite the bullet and have a professional come out and thoroughly examine the entire system and equipment. Regards.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Unit seems too big with too few supply ducts. Where are you? Duct work in the attic or under the house? Ducts shared by the heating system? What and where is the return duct? How long has the unit been in place? Has this always been a problem or is it a recent problem?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hugh Wong wrote:

Hmmm, Where are you located? How old is the house? Is the bed room facing South other than furthest from a/c unit. IMO, you have an oversized unit for the size of house. BToo big a unit is nno good for optimal effciency. Idea of bigger is better in a/c unit is wrong.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Are ducts insulated, I did mine and it made a big difference. Have you tried running the fan continously, I do that on hot days and nights it makes maybe a 3f difference in balancing it over 24 hours. Do you have any vent dampers on the air handler-furnace. I put them in to get a more balanced heat and AC, but be carefull you dont want to cut air much to other rooms or you risk freezing the coil. On one long weak run I had a bigger insulated duct and a larger vent to reduce resistance and get more airflow. A window AC would do it today to get you cooler, but there maybe several small jobs that could balance you out fairly closly, just the fan on continously and a small adjustment to floor registers might help alot. Everyone saying 7 isnt enough isnt true, size is what matters not the number of them, if it wasnt enough for airflow you would have frozen the coil and had no AC many times before, till you thawed it out. Insulating can be easy to do for two people, vent dampers are easy to install Diy. While you are at it if you cant examine the interior AC coil cut in a hole in the ducts and make a cover so you can look at it, it needs to be clean and mold free or performance suffers and electrical costs can go way up. To cut a hole you must know exactly where the coil is so you dont ruin it. Is this house in a hot unshaded area, because that is a very large AC for your sq ft, does it cycle alot on the hottest days or run near continously, it should run continously if its not oversized on the hottest days to remove the most humidity, an oversized AC wont run long enough to cool the farthest run so running the fan continuosly might be needed and worth a try .
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.