Additional return vents


  #1  
Old 04-11-13, 06:44 PM
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Additional return vents

I'm thinking of installing additional return vents on the upper floor--one in the front bedroom and one in the master bedroom. The attic fan and 18" of insulation just aren't doing the trick. I think it may because of the open design of the house. Half of the first floor has vaulted ceilings which are open to the upstairs hall, which both of these bedrooms are located off of. There is one 14x14 return on the first floor and one 14x14 return on the second floor directly above, both are in the vaulted area of the home. My question is this--will it help to install a small return vent in each of the bedrooms? I'm think something like an 8x10 vent in the ceiling of both rooms. I can easily tap off the main return duct from the attic and branch off to each room. All of the heat from the entire first floor rises up and collects on the top floor and the AC just can't keep it cool up there. One return vent on the wall in the hall upstairs just doesn't seem adequate to suck all the hot air off that floor. Yes, I know, I should do a Manual-J load calculation, but I won't be doing that. Plus I don't need to do a load calc to know that it is too hot upstairs and comfortable on the other floors. BTW, I tried closing off most of the first floor vents and return register and that didn't help. I need to get the heat off the top floor.
 
  #2  
Old 04-11-13, 08:16 PM
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Hi Mossman, I'm not an HVAC pro, but having returns in each room where there is a supply should help. I'm sure you know that supply and return should be reasonably matched, however the summer vs winter delivery requirements are different. When you close an upstairs bedroom door, you create a smaller zone and with a supply and return in that room you have a better chance of reaching the desired temperature. Open the door and your cool air pours out and the warm air pours in.

One concern I see is connecting to the existing return. Based upon its size at the air handler, it can only move so much air. Relocating current capacity to other rooms and closing off low returns may help to maintain a balance. My first house used high/low wall cavity returns. Open one and close the other with every season change.

Bud
 
  #3  
Old 04-12-13, 06:07 AM
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I like your thought process, especially about putting the returns in the ceiling. I'm no HVAC pro either but I do a lot of opening and closing supply vents between summer and winter to balance the two floors of my home.
 
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Old 04-12-13, 08:19 PM
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Closing supply vents on the lower floors (basement and 1st floor) doesn't seem to help much. I need more return on the top floor. I could try partially blocking the return on the 1st floor I suppose. I currently have the return in the basement (3/4 underground) closed. Three returns total, 2.5 ton unit, 1700 sq ft home.
 
  #5  
Old 04-13-13, 04:02 AM
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Adding extra vents and then selectively closing some will maintain the proper airflow through the system. Just closing some reduces flow and capacity.

By not doing some type of heat loss/gain calculation it is hard to know where to start. I'll let the HVAC pros jump in and see if they have any thoughts.

Bud
 
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Old 04-13-13, 08:13 AM
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Bud raised a good point - I installed a couple extra vents in my house before I started messing with which ones were open, just closing some of them can cause issues due to the reduced flow and increased pressure.
 
  #7  
Old 04-16-13, 09:34 PM
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More returns are always helpful. Maybe I'm older but I remember the time when every room had a return. In my 3000 sf house, I have two returns, one for each system. And returns on the ceiling are helpful.

I am also a big fan of zoning. Install some dampers and thermostats with a zone controller and it will work great if planned correctly. Its a job you can do yourself and cost is pretty reasonable. Set your thermostat and that is your temp. Don't use an area, turn it off. Spend your money heating and cooling the areas you actually use without closing vents which I am NOT a fan of.

Two or three zones is likely plenty. Just make sure you have enough vents on each.
 
 

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