Residential HVAC unit 4

[MotorCity]

Hello HVAC friends.....structural guy here hoping you can point me in the right direction.

The problem is that when the AC unit runs (not sure what size, need to check) very little of the cold air makes it up to the second story.

The air that does come out upstairs is cold, but the flow is minimal. So, I'm thinking that because the air is cold, the issue is not with the AC unit but is probably due to an undersized fan in the furnace which blows the cold air through out the house. If that's the case, I thought of installing in-line duct fans (which are not cheap) or installing a more powerful fan in the furnace.

Am I on the right track, what would you do?

 

[Compositepro]

Your test results are not at all unusual. There is significant pressure drop in ducting along its length. You have to restrict the flow in other, closer, grills until you have adequate flow at the end. Flow balancing is an iterative process. When you adjust any grill it will affect the flow out all the others. Repeat until the flow from each grill is adequate for the cooling load in the room. Keep in mind that the return flow from the second floor goes to the first floor so you do not need much flow through the first floor grills.

 

[IRstuff]

How old is the air handler?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[LittleInch]

Ok now we're getting somewhere.

So my little research show 1/2 hp fan motor will give you about 1400-1600 cfm at some reasonable output.

That seems to equates to about the same or maybe a bit less in square footage of the rooms to get some adequate cooling air if it is balanced out as noted above.

How many square feet is your house in total that you want to cool?

If its a lot more than 1600 ft^2 then your fan is undersized.

what I would buy though is an air flow meter / fan so that you can balance your rooms better than just "feel".

https://www.amazon.co.uk/Lorsoul-An...ocphy=1007109&hvtargid=pla-684533904184&psc=1

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[willard3]

Buy a velometer, measure the volume and then you'll know where to start.

If you can't measure it, you don't know what your problem is.

 

[chicopee]

Graphing the fan performance curve and the system loss curve is an engineering tool that may not have been used when the specification for this system were developed.

 

[LittleInch]

Any update?

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[MotorCity]

Based on the square footage, the fan is undersized. I have adjusted all of the grills (open/closed) such that the air flow upstairs is about as good as its going to get without doing anything more. The air flow is more than before and tolerable, but not great. The plan is to wait and upgrade the fan in a year or two.

 

[LittleInch]

Thanks for the update. Hope the info was useful and at least you now have some cool air upstairs!

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Also: If you get a response it's polite to respond to it.

 

[williammark]

There is a problem with fan or blower just check its CFM or may be a trouble with the duct routing. I will recommend to go with the best service provider.In USA many service providers are working but if we talk about Kenly, Pitt and Johnston i will suggest Comfort Shield HVAC Services.

 

[LittleInch]

Please don't hijack another thread. You have your own thread on this subject.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.