Split level house cooling/heating question

5 years ago

Our house is split level: lower level 1 = family room, garage....next level 2=dining, living, kitchen, breakfast, bath, bedroom....next level 3=entry door/hall....next level 4=master bedroom, half bath .... next level 5=2 bedrooms, full bath.

There is only 1 a/c unit for the entire house.

In summer using a/c the lower levels are too cold and upstairs bedrooms too warm.

How many vents on lower levels can I partially or fully close without damaging the a/c unit in hopes of keeping lower levels less cool and upstair bedrooms cooler?

Featured Answer

PRO

Austin Air Companie

5 years ago

This is a fight of design vs: Science and no two people are alike when it comes to comfort. Science nearly always wins, if you want to know what to place your money on.

The builder said that by building this home everything looks good "on paper". Then people move in, start using it and find the "lack of judgement" used by the builder.

But it doesn't stop there... because design of a system "costs money". There are ways to cheat --all with varying degrees of success. (trade offs if you will.) The home with a better design would cost more. The next argument may ensue stating that the home is a million dollar home. So how much the building cost vs the design of the HVAC system and how well or not so well it works -- homes are not priced that way. Imagine if they were?

We have a lovely cap cod. You can enjoy endless sleepless hot steamy night for the low price of $XXX,XXX.00 ( can't let numbers clog up thinking so pick a number)

Now because I don't have a crystal ball, or even a flying rug for that matter. You get a clearer picture of what you're up against. (no two homes are alike, let alone the people involved and what or how they view fixing comfort problems. There is no gadget or easy fix to a "design" problem... merely trade offs. The easier fix in a hot real estate market is to sell the box, find a new one now armed with the knowledge of "science". (It's far easier to heat and cool a single story structure --- but land is expensive. Yeah so is HVAC redesign.)

As you've discovered with your problem, hot air rises to upper levels and cold air falls to lower levels.

Your ductwork for the upper levels are likely maxxed out. The system for this house is probably 5 tons if I had to guess. That amounts to roughly 2000 cfm of air. (400 cfm per ton) Closing down vents forces that air with no where to go. You can't cram additional air down a duct that is maxxed out AND expect the system to work.

That function causes a whole slew of problems depending on a wide variety factors.

This problem is complicated vs cost vs expectations vs what is achievable with the current structure. 5 different levels with 1 system? You've got your work cut out for you. How much room is there for HVAC? Remember this is science, not magic. Architects never do me any favors, I can tell you that much.

I've pulled off more than a few miracles in my day. None of them were what I would consider "cheap". Design means everything.

I service the Katy, Texas area.

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Comments (9)

krissie55
Original Author
5 years ago
last modified: 5 years ago
Austin Air: Thank you. The house was built in 1965 and has a 2 ton Carrier a/c. The a/c was replaced in 2015 with same brand and tonage. I am in the DFW area.
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Elmer J Fudd
5 years ago
last modified: 5 years ago
To improve the situation, you'd want to add return ducting on the upper level. Maybe have an HVAC person over to see if that's feasible. Hot air will always rise and cool air will sink but with a single system covering multiple foors, boosting the return on the top level(s) should help.
krissie55 thanked Elmer J Fudd
PRO
Austin Air Companie
5 years ago
The house was built in 1965 and has a 2 ton Carrier a/c.

That doesn't sound right to me. Especially DFW area and the layout of this house sounds larger.

2 ton for DFW on a good day might cover 800-1,000 sq ft home built in 1965. How big is the house?
krissie55 thanked Austin Air Companie
krissie55
Original Author
5 years ago
House is 2600 sq. ft. There are 4 steps from level 1 to level two.....3 steps up to level three,....10 steps up to level 4....2 steps up to level 5.
PRO
Austin Air Companie
5 years ago
last modified: 5 years ago
ok, from that... if DFW means Dallas / Fort Worth, Tx. 2600 Sq Ft house, built in 1965. There is no way possible a 2 ton AC would work. (not enough capacity to cool a home this size built in the year it was built, regardless of windows, ceiling height etc. )

If the house was built circa 2020, you *might* be able to get close to a 2 ton unit for this area, with that sq. footage. The ability to seal homes today, wasn't possible in 1965... many homes didn't even have air conditioning then.

I grew up without air conditioning. I've been doing air conditioning work for over 26 years.
krissie55 thanked Austin Air Companie
krissie55
Original Author
5 years ago
last modified: 5 years ago
Looks like putting a window a/c in bedroom that needs more cooling is my only option at this time. Adding a second a/c unit for upstairs would cost too much since ducting would have to be altered. Downstairs is too cool as it is.
Elmer J Fudd
5 years ago
How about a mini-split system with a couple of units upstairs as a supplement to the existing equipment? It's an easy retrofit item and they're not as unsightly as a window unit. Though more expensive.
krissie55 thanked Elmer J Fudd
krissie55
Original Author
3 years ago
Problem solved for this winter. Had to move downstairs from upstairs master bedroom due to health issues. The cold air from up stairs was funneling downstairs and the heat from downstairs was going upstairs. A drape over doorways (no doors) from entrance hall to downstairs rooms is keeping the downstairs nice and warm. Hope this will work for the summer when we have air-conditioning on. Thanks everyone for your suggestions.