Conceptual Q: 2 story home, x2 HVAC units

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1:12p, 9/27/23

AG

If a large Texas 2 story home has a dedicated HVAC unit for each floor (with the ground floor unit being slightly larger than unit for upper floor). As I've been told, the general recommendation is that the downstairs temp should be ~2 degrees cooler than upper floor since heat rises.

Wouldn't it make more sense to install the larger HVAC unit for upper floor and you could circumvent this temperature gap/offset?

Or am I going full dog brain?

Thanks & Gig 'Em

agnerd

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2:48p, 9/27/23

AG

Smaller unit is usually for upstairs since upstairs usually has less area to cool.
Living areas and kitchen are usually on the first floor.
Max cooling occurs during the afternoon when most people are downstairs.
Easy to cool upstairs bedrooms at night when it's cooler outside.

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EMY92

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5:08a, 9/28/23

AG

If area is equal, the 2nd floor will have a much higher heat load due to the roof. The first floor has a conditioned space above, so the only heat load is through the walls and windows. In this case, the 2nd floor would have a larger unit.

The only real way to answer your question is to do a load calculation for the house.

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In reply to EMY92 • 7:33p, 9/28/23

AG

Yes thank you this makes sense to me.

We have a high vaulted living room ceiling and a "media" room with walk in storage over grave area that is always way hotter. Little ones nap mid day so it's a bear to cool the upstairs where their rooms are.

Thanks & Gig 'Em

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In reply to agnerd • 7:34p, 9/28/23

AG

I understand your explanation. I guess I'm just in a bit of an atypical situation.

Thanks & Gig 'Em

ukbb2003

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In reply to ThreatLevel: Midnight • 9:54p, 9/28/23

ThreatLevel: Midnight said:
Yes thank you this makes sense to me.

We have a high vaulted living room ceiling and a "media" room with walk in storage over grave area that is always way hotter. Little ones nap mid day so it's a bear to cool the upstairs where their rooms are.

Did you mean to say over the "garage area"? If so, guarantee you there is no insulation between the ceiling of the garage and the floor of the room.

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In reply to ukbb2003 • 9:16a, 9/29/23

AG

No the house is built over an Aztec burial ground. Lotta weird stuff going on TBH.

Yes auto (in)corrected.

Thanks & Gig 'Em

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ukbb2003

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10:43a, 9/29/23

Are you able to get to a place in the attic where you can see between floors over the garage area?

tgivaughn

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3:39p, 9/29/23

AG

Until you get Manual-J specific, designers use SF/ton: 475sf or 525sf if there's an insulated floor/attic above it.

but of course your thinking is otherwise on target; now add/subtract factors ala open spaces vs closed spaces (bedrooms, bathrooms), 3-occupants, insulation, windows/solar/wind, electrical heat, et al.

http://rb.gy/z9zqv

https://www.acca.org/standards/technical-manuals/manual-j

Ten words or less ... a goal unattainable

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In reply to ukbb2003 • 5:00p, 10/5/23

AG

I'm thinking it might be easier to make a hole on the garage ceiling sheet rock and investigate from that angle no?

Thanks & Gig 'Em

Gary79Ag

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In reply to ThreatLevel: Midnight • 9:13p, 10/16/23

AG

ThreatLevel: Midnight said:
No the house is built over an Aztec burial ground. Lotta weird stuff going on TBH.

Yes auto (in)corrected.

Is it located close to Kyle Field?

aka The Legendary *******!!!

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