Well, I have just about called everyone in Forida & Louisiana about this RB fiasco I'm in. I must say I will not delete my posts , because that would not be the right thing to do. I will say this, I owe energy rater an apology. You are correct. If one side is reflective, and one is not, the reflective side will face in. My dig at you was in response to you poking at me about my membership. I do not like to start a war of words, but you kinda **ssed me off the way you attacked me. That said, I have learned something today that I won't soon forget and hope you accept my apology.
Energy Star, are you saying that you called all your customers so you can fix the problem on your own dime? That's quite professional of you if that is the case.
I only ever installed a RB that's reflective on both sides anyway. I do not buy it with the reflective coating only one side, like I said it's reflective on both sides, so I'm ok.
Originally Posted by perrybucsdad
http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html. A 16 to 42% drop in heat transmitted across the insulation seems pretty significant. This really could easily be a DIY thing.
Please see my earlier post. If your neighbor has gotten his 2nd floor to cool, by closing the lower RA, you can always try it and see. Make sure your air filter is clean, and leave fan on continuous. I'd much rather close some lower outlets, rather than close a return due to the possibility of starving the air flow, but go ahead and try it. Watch the larger copper line on the outside AC unit for any signs of a light frost. If frost starts to show up, then start opening the lower return air, as the indoor evap. coil above the furnace is starting to freeze over, and it will continue at the lower air flow, if you allow it to!!
Coupon----199 special for 3-5 hours of checking for leaks, insulataion, etc
Originally Posted by perrybucsdad
I tried it. It works. I am worried about damaging the system because I am listening to the Professionals in this forum. I blocked the downstairs return for 48 hours. It made a significate improvement during our hottest days of the year so far(81 and 82). I am still going through with the audit to see if there is a way to resolve the issue without blocking the return. I am beginning to think that the system is undersized even after the installing company assured me it was not. I spoke to 2-3 other companies and asked what size I should have and all of them said bigger than what I have. I will know more on Tuesday.
Originally Posted by wahoo
I am glad to hear it works; it validates a theory I have been proposing here for some time. That theory being that during the heating mode the return should be low in the house and during the AC mode the return should be high in the house. Calling it a “band aid” is a totally inaccurate statement. It optimizes circulation by first removing the unwanted air (upstairs in your case) and then draws the cool downstairs air toward the return.
Originally Posted by efelkey
For anyone who thinks inducing this type of air movement by covering a RA in a two story house is a” band aid”, I would love to hear why. And maybe an explanation could be given for why hindering the performance of an AC by covering a return could yield better overall performance.
To me this is a duct layout problem that few pros would recognize. I am anxious to hear what your auditor says. My guess is that he will look to zoning, split systems, dampers, more insulation, and sealing, which are all secondary problems, if any.
Think about it, your system was installed by a pro, did he get it right? Will the troubleshooters get it right? I say no. They will look to your wallet for a solution, not their liability of another poor industry-standard installation.
The concept of high and low returns isn’t a new theory and has been discussed many times on HVAC-Talk.
Originally Posted by Brian GC
I believe what Pros meant by band-aid fix is that they are assuming that the upstairs and downstairs returns aren’t independently sized to act as the sole return for the entire house.
In other words, the return ducts weren’t sized with the intent of blocking one or the other off depending on season. If the upstairs return is by chance or by design sized properly for the entire home, then problem solved (though not ideal). If it’s not, the equipment will eventually be damaged.
When properly designed, rooms or areas are conditioned by providing conditioned air through supply lines, not by pulling conditioned from other areas.
The experiment the OP performed most likely worked, not because the proper amount of conditioned air was being provided to the upstairs through supply lines, but because additional Conditioned Air was being pulled from the downstairs supplies to the upstairs returns.
A very good design will have several returns throughout the home. The best will have a return if every room. From what I understand, you can’t have too much return.
A system should be balanced by supply which a Zoning system does, not by return.
As many smart people on HVAC-Talk have posted; think of air flow in terms of water and everything starts to make sense.
I suggest researching Static Pressure on HVAC-Talk to determine what the impact of restricting return results in.
A question I have is; what is more energy efficient, conditioning a room with the properly sized supply lines and the proper amount of supply CFM and properly sized returns? Or, with undersized supply and oversized returns with the intent of pulling CFMs from other areas? In other words is pushing air to condition a room more efficient than pulling air? Are both energy neutral?
As an example, it’s my understanding that with water, it’s more efficient to use a pump that pushes water up 10’ than to use a pump that pulls water up 10’ (but I could be wrong).
I do not agree, I believe what the Pros meant was that you do not use placement of return air to improve the performance of any system. If they recognized the importance they would have recommended adding another return upstairs as a cost effective solution. Also, if they knew the importance, someone would implement zoning returns.
Originally Posted by Rdy2Zone
The OP’s experience is a classic example of how return placement affects the overall performance of a system, even when the cfm’s are reduced. This validates what I have said before, “Units can be made smaller if returns are placed properly”. But in this case, most pros would suggest a larger unit.
You are correct about the pushing and pulling of air, but that is negated when the correct sized ducting is used throughout the system.
The conditioned air is not only being pulled upstairs, other things are happening as well.
In the original RA configuration:
Maximum supply is being distributed throughout the house.
The downstairs RA is removing cool air that should remain in the house.
Hot air naturally rises up the stairway.
An over abundance of hot air pools upstairs and is not being removed at the proper rate.
Cool upstairs air slides down the stairway.
In the blocked RA configuration:
A diminished supply is be used with better results.
The cool downstairs air is not being removed.
The downstairs produces more cold air and begins to supply the upstairs with cool air rather than hot air.
The upstairs RA is removing the hot air at the proper rate where it naturally collects.
Cool upstairs air cannot slide down the stairway while the unit is running.
Return air can remove unwanted air at the same rate cool supply air can be pumped in. It is two sides of the same coin. Recognizing the effects of air density and how air migrates is key to an efficient system. But getting pros to grasp it, even when stories like this pop up, seems impossible. The OP, and millions of others, waste tons of money on poorly designed systems that could operate so much better.
Two floors ,two systems or two zones.
Reeturn cation like blocking the firs floor helps some,but the problem is the supply system is not correct, will not solve the problem.
The first and second floors will each require different cfms in cooling then in heating,zone it even if it's manual dampers for each floor that you adjust for he season.
Originally Posted by Brian GC
I think its a great idea for the audit OP. I'm looking forward to reading what you found out.
one thing you can ask your auditer to do is to show you where the leaks are..make sure you check the wall to floor junctions and wall to ceiling junctions. often moldings are installed covering up the joint, but still attic and ambient temps enter.
leaks in ductwork should also be pinpointed. if you have a lot of duct leakage then the tons of conditioned air entering your house is lessened.
also if you have several large leakage sites, the smaller leakage areas will not show up until large sites are sealed.
(think of a bucket with small holes and large holes..fill it with water
and the large holes will let the water out..plug the large holes and the water leaks from smaller holes)
I think you are on the right track.
heck of a price on the audit btw, I couldn't do it for that price!
and energy star..glad you made your calls, and I was not poking you about pro status, truly I am glad that you have joined.
hope everyone has a happy labor day weekend with little labor.
The cure of the part should not be attempted without the cure of the whole. ~Plato