I have returns top and bottom in the rooms with the high ceilings. I used to switch them around for summer or winter, until I almost fell off of a ladder one day trying to reach one of the upper ones. It is about 14 feet high.
I mentioned this to Beenthere and he suggested leaving it open, so I tried this by always leaving the top open but adjusting the bottom. Now all returns are wide open and performance in every room on every floor is so much better. I could have really used this last winter.
top bottom supply and returns are the dumbest design I have ever seen.
Originally Posted by jerrod6
ugly as hell in a small room. most homeowner dont bother,forget or even know what there for. And really makes for a ugly looking wall.Not to mention someone could get hurt as you just mentioned.
There are reasons why the OP got favorable results from blocking a return and Jerrod did not. The OP had a massive stagnant zone and Jerrod did not. Jerrod severally reduced the volume of his unit, the OP apparently did not. And, the OP dramatically changed the overall airflow within the house, Jerrod did not. So the two examples cannot be compared so easily.
Coolmen, you are correct about two returns high and low along with a supply or two in each room being unattractive. I do not think it is the best setup functionally either. Furthermore, I would imagine it would be a nightmare to install. I would not suggest such an installation.
The setup I think is the very best would be two centrally located returns, one at the highest point in the house, the other at the lowest point in the house. Each should be adequately sized to supply the unit and be zoned. The high return used for AC and the low return for heating. If the HVAC industry would extensively test this setup, do a cost savings analysis, and teach the field it benefits, people would be more comfortable at a fraction of the cost. But the added labor would be met with much resistance.
IMO conveniently installing ceiling returns for heating systems is a crime, and asking clients to run ceiling fans in the winter to reduce the problem is a counterproductive “band-aid”.
Yeah I wasn't being careful in that one case but other than that I have no problems with them. Ugly - mine have been changed to match each room design so I don't think they look that bad..gold plated,white, silver or black iron. I do see that when both are open there is air moving around each one.
Originally Posted by coolmen
My biggest surprise is that with all of the returns open there is still enough movement to move air at the farthest one and that the air delivery in entire house has has improved.
I can't speak about the installation because I don't have that experience, but it seems like there are two duct systems running through each room in the house except the bathrooms. There are returns in the hallway on each floor too but I don't know how that was installed either, just that there is air moving around them.
Originally Posted by Brian GC
Comfort within a room isn't just a matter of how air is moved around. It is a large portion, definitely, but it is not everything. Whenever we get into these discussions regarding supply and return grill locations, inevitably the other large contributing factor to human comfort within a given room or space is overlooked.
Originally Posted by jerrod6
One must remember that the human body is ALWAYS shedding heat. The only thing we're trying to accomplish with heating and cooling a house is control the RATE at which a body loses heat. If it loses heat too quickly, we're cold. Too slow, we're hot. If the air is too humid, the additional heat rejection mechanism of the human body, perspiration, is hampered. Air too dry, evaporation of perspiration from the skin occurs rapidly (we are always sweating, whether the drops of water are visible or not. Place your hand against a cold window pane in winter and watch it fog up), and depending on air temperature, can either aid one in feeling cold, or if the air is warm, the skin can dry out.
Additionally, objects and surfaces that surround a person also determine rate of heat loss from the body. Ever been in a room where the air temperature was fine, but you still felt cold? Blame it on a nearby surface or object that was colder than the air in the room. You were losing heat to that object directly via radiation, which doesn't care about air temperature. Same is true for summer cooling. If the walls and ceilings and floors are warmer than the air, you will feel warm even if the air is relatively cool.
I have found it quite enlightening to walk around a house on a hot day with the a/c on, holding an infrared thermometer, and aiming it at walls, ceilings, and windows/doors. Single pane windows on a hot day are quite an eye opener when shot with an IR thermometer; even more so when there's a double pane, low e, argon filled sliding glass door nearby. Shoot the double pane job and then the single pane...the temperature difference between the interior and exterior panes is quite revealing. Another poster on here named Designer Dan has the phrase "it's all about windows". It's becoming more plain to me exactly what he's driving at.
So, we can sit here endlessly talking about supplies and returns, all the while ignoring the other vital component toward making a person comfortable, the building envelope!
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.
Here's how I've partially settled this problem. In summer, I shut (totally or partially) a few air outlets on the first floor, and in winter, I do the same on the second floor. Heat goes up, and cold air goes down.
Originally Posted by efelkey