Want to install cold air returns, but will it fix the problem??? The pros say no

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  #1  
Old 07-11-18, 01:37 PM
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Want to install cold air returns, but will it fix the problem??? The pros say no

Our house is 30 years old with a brand new heater and 5-year-old air conditioner, I have posted here about airflow before . Rooms in our upstairs are hot in the summer and cold in the winter. The only room that is comfortable is our master bedroom. We have the only return air vent on the floor.

Approximately 2600 sq foot home 2 story house. I want to retrofit and install return grills in each room. As I think this would help (downstairs is 7 degrees difference, cooler in summer and warmer in winter). Every pro I have talked to so far, as wanted to install a 2nd system for upstairs. I just don't want to install a system in the attic as I think it would be costly.

Our HVAC's response: The problem is your unit is set up a specific way when you start adding returns that are not installed from day one it doesn't work as well. We can run Supply and returns in each room and put a system in the Attic. Or we can put in a ductless unit. The other thing that you have to take into consideration is the path of least resistance just because you cut returns in the walls for upstairs doesn't mean that the unit is going to pull from those spots like it does the other ones

Am I fighting a losing battle am I wasting money and time trying to retrofit returns into a 30 year old home, should I be focusing on adding a 2nd system or is this them trying to upsell me?
 

Last edited by emshomer; 07-11-18 at 01:38 PM. Reason: missing words
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  #2  
Old 07-11-18, 02:20 PM
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Where is your air return located?

Do things improve if you leave the room doors open?
 
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Old 07-11-18, 02:30 PM
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The idea of adding more returns is valid but it's not that easy. I'm guessing you have a heating system where the A/C was installed later..... after the original installation. That means all the returns are low to the floor. The returns need to be high in the wall for A/C and low to the floor for heating.

How will you get additional return ducting to the second floor ?
It usually means commandeering a closet to run the duct(s) thru.
 
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Old 07-11-18, 07:26 PM
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So to back up, since I left a lot of details out.


Our air handler and heater is located in the basement with ducts going up to the 1st and 2nd floors. The 2nd floor has only one air return in our master bedroom. Generally, this room is the most comfortable.

We have 4 bedrooms - Our kids and guest rooms do not have air returns at all...Since I'm not the original owner of the home, I do not know if the AC was installed later, but I do know this outdoor condenser was installed in 2012.

The only return as I said is located in the master bedroom, on the wall close to the ceiling. All the supply registers are located on the floor on both levels.

Our attic is sprayfoam insulated and sealed that spans the entire upstairs level. I guess we could add a 2nd unit up there, but wasn't really thinking about shelling out that much.

What I thought about doing after talking with a friend was ....even though the current return in our master bedroom may be slightly undersized for the entire floor. If we did some alterations and installed a duct box in attic above the wall returns, and closed off the current return grill in our master bedroom and then installed a flexible return duct into each bedroom and one in the 2nd floor foyer at the landing and each return went back to the duct box we would install that would connect to the current 2 bays of return that is current in the master bedroom.

The master bedroom current return would be closed off with sheet metal behind the grill opening and painted black so one wouldn’t notice a visual change at all but we would also install a 6” ceiling return into your master bed. Being we would not be pulling from the return grill currently in master bed but from newly install ceiling returns it would allow the current roughly 350 cfm we have to be equally split and pulled from the entire 2nd floor and not just our master bedroom.
 
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Old 07-12-18, 04:18 AM
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Two floors two units IMO. They are two totally different zones that need two separate units to work well. Cheaper to run, you have redundancy. Comfort Comfort Comfort. That is what you are paying for.
 
  #6  
Old 07-12-18, 10:17 AM
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With one system for both floors, getting the same temperatures on both floors is almost impossible. Having temperatures a few degrees different is the norm. For anyone to make an educated guess as to what could be done it would be better if that someone could be at your residence to see the actual installation. For any good recommendations more information is needed such as: (1) the size and model numbers of the furnace and A/C unit; (2) the size of the existing duct-work both horizontal and vertical runs; (3) the number of supply and returns in each room; (4) A diagram of the house (floor plan). There are a lot of good guts that monitor this site, all with varying ideas, Some good some bad. Lastly, I come from the contractors of yesterday that could actually try to fix problems, Today, I have little faith in most contractors
 
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Old 07-14-18, 07:10 AM
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Cheap fixes

Try the cheapest fix of all. To balance the rooms to even temperatures simply flick that thermostat fan switch to “ON” and leave it alone. Cooler and warm air returns to the box and redistributes the air into ALL rooms over and over. This will become comfortable unless you’re. One of those people that constantly play with the thermostat ... up, down, auto, on off......
 
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Old 07-14-18, 09:33 AM
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Thanks for the replies. I guess for the most comfort, it will make sense to get a 2nd unit. I wasn't trying to get exact temperature as the downstairs but aim to get it in 1-3 degrees. My theory of adding more returns may have worked, but the cost of running new returns from 2nd floor to basement is not a straight shot and most installers have already quoted labor costs that almost is equal to the cost of a new unit.
 
  #9  
Old 07-15-18, 08:52 AM
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You could try "HVAC01453 "s idea to run the fan 24/*7. I have run my fan 24/7 for 40+ years in 2 houses to help even the temperatures. IT has worked for me, you should try it If it doesn't help , you could then opt for a 2nd unit.
 
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Old 07-15-18, 08:11 PM
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So keeping the fan on? Does that put extra strain on the system day in day out? Guess not if you keep it on 24/7...what about electricity costs?

i will say with the fan on the temps seem better and closer to the thermostat reading. I have a nest and these temp sensors in each room and they are all reading within 1-2 degree of the thermostat so thank you steamboy and hvac for the suggestion of leaving the fan on. The real test will be a 99 degree day to get that upstairs cooking.
 
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Old 07-16-18, 10:58 AM
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Yes, it will increase the cost of operating the system, how much depends upon the size and type of the blower motor. Standard three or four speed selectable motors will have the highest cost and the variable speed motors in higher end equipment will have a lower cost increase.


"The returns need to be high in the wall for A/C and low to the floor for heating."

Sorry, Pete, but it isn't quite that simple. The location of the return duct is less important than the location of the supply. For cooling you want the supply high and the return low for maximum efficacy. The reason is that the discharged cooler air will mix with the warmer air at the ceiling and cause convection currents to flow in a generally downward direction. People will feel cool(er) if their heads are cooler than their feet. Discharging the cool air at the floor level will simply cause the cooler air to pool at the lower levels and the convection currents will be minimal. For the same reason you want to discharge heated air low as it will naturally rise and set up the convection currents.

Don't believe me? Look at the supply and return ducts in any large auditorium or meeting room. In these places, often holding hundreds of people, the primary need is cooling, even in the winter. The returns are always placed low and the supply is high. For a residential situation where the time spent heating is about the same as the time spent cooling, the ideal location for the return air is about waist level. Ducts/registers for heating would be in the floor or lowest point of the walls with the ducts/registers for heating placed high, generally with a means to switch between the the two when going from one mode to the other. Trying to "make it work" with high returns in a cooling mode is less effective because you can move a lot more air from the supply than you can move through the return.
 
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