1950's Tri-Level

[alex51026]

I live in a 1950's Tri-Level home in Richmond, Va. that was designed with all rectangular sheet metal ductwork. It was designed for heat only. The main return is in the lower level and every room (minus the kitchen and bathrooms) have small returns a foot off the floor, opposite of the supply vents. This set up works perfectly for heating. I have a good amount of airflow on the main level, better airflow on the lower level, and very little airflow upstairs. During the winter the temperature between floors is not noticable, but in the summer the temperature on the upstairs will be 76, 72 on the main floor, and 68 downstairs, even when its 100+ outside. Besides doing a cut in and putting a 1.5 ton system/ductwork in the attic, are there any other remedies to this problem? I've thought about putting a high return in the upstairs hallway and dampering the other returns, but with the lack of airflow in the upstairs level I don't know if the high return will do much to solve the problem. Any thoughts are greatly appreciated!

[dandyme]

can't see a thing from here, but

are you sure the duct isn't apart?

have you had a contractor look into your issue or do you intend to undertake this task alone

DEPENDING: on how the duct is separated for each level_ zoning may be an alternative IF the duct work is deemed acceptable

of course the duct may be too small as it is with what you're trying to achieve

there again, can't see a thing through this computer

[Chris_Worthington]

Moved to AOP

[alex51026]

dandyme,
The main supply line comes out across the crawlspace (under the main floor) up into the utility room and then under the floor joists between the lower level and the upper level. Other than where it comes out of the crawlspace it is enclosed by drywall. The supply runs to the lower level go over between floor joists and then turn down. THe ones to the upper level go over across the floor joists and go up.

I am actually a sales rep for a contractor, but I am stumped by this set up. I have a chase option in a bathroom linen closet (currently a laundry chute) that I could install a high return.

This is a tricky set up. The first time somebody told me it was a "heating only setup" I didn't know exactly what they meant, but when you compare the winter and summer heat and cooling/un even temperatures it makes perfect sense.
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[skippedover]

Alex, in all likelihood, you're 1950's design precedes the science put into load analysis and duct design as it is today. The system works better for heating because the laws of physic are that warm air rises. So the excess heat that would otherwise be on the lower level, augments the missing heat on the upper level, thus accidentally balancing the system. Pushing cold air up 3 floor is a whole different issue from pushing warm air up 3 floors. I 3rd floor return would obviously create additional airspace for cool air to be introduced to the 3rd floor, provided there's a shortage of return air overall. However, air is stupid, both at the supply and the return paths. If there's already sufficient return air, then adding to the 3rd floor may not gain a thing, as the return air will be drawn from whatever path has the least resistance to airflow.

If you really want this issue resolved, you'll need to start with a room-by-room load analysis to determine what the most basic shortfalls may be (supply outlet sizes, for example) and then you can proceed to duct design. How much of the duct is available for evaluation and/or modifications is not something I can determine from here. But it sounds very much like a system where I'd recommend, drop the ducts on the floor and start from scratch.

[alex51026]

Skippedover,
Thanks for your response. I have 6 supplies on my lower lever and 5 supplies on my upper level. None of the supplies are accessible, they are all enclosed in drywall. My upper level is the same length, but two feet wider. My knowledge determines that I have a greater cooling load on the upper level, and also have less CFM running to that level. I dont know if doing a cut in and adding a 1.5 ton with 8, 6-inch supply vents would be a better overall affect or putting a ceiling cassette mini-split to augment the missing cooling. I'm thinking the 1.5 ton would be a better solution. I would then do an official load calc on my house to make sure i'm not oversizing my upstairs. Worst case scenerio I could put 1-2 supplies to my main level. The oppurtunites are endless!

I was considering replacing my Heat Pump Air Handler with a gas furnace and cased evaporative coil for more comfortable winters, but lets face it, summer is worse in virginia than the winter.

Any further thoughts? do you think i'm on the right path?