DIYbanter - View Single Post - Optimal setting for 2 A/C unit in two story house

sosessyithurts

wrote:

Is this recommended? the builder of the house suggested that I should
always keep both units within one temperature degree of each other.
However this makes more sense to me.

you say you can program the units, that's nice.
this way you can set them and forget them right...

anyway

cold air sinks, hot air rises

depending on the interior of your home, your upstairs unit is going to
work harder
to acheive the same thing as the downstairs unit

hot air rises.

the upstairs is taking a more direct hit from the sun

that's why I say the upstairs unit is going to work harder

I did a little research for a friend on this same subject about the
effieciency
of a fluctuating temperature scheme...

it is actually cheaper to fluctuate...
some argue that you pay to cool a house back down...
in my research, I discovered it does not cost more to cool a house back
down

So I like your scheme, I think your maximizing your resources.

I've got this down to a science, I have 2 windows units

for the one in my bedroom, i decided it is better to leave the ceiling
fan off.
reason: cold air sinks... so.. i let the ac run on low.. it fills the
lower portion of the room with cold air... as the room fills up with
cool air the target temperature is reached quicker! than if I had to
cool the upper portion of the room as well.

by turning the ceiling fan on, I have to cool the whole cube! by
leaving the ceiling fan off.. i only have to cool the lower portion of
the room.

another fine example of this. a friend installed a sun room, a sun room
with glass ceilings can gather alot of heat up in the top...

I told him.. why not install a vent at the gable end of the sunroom
(where it ties onto the house)... put an air vent hose on the vent..
and suck the hot air out of the upper portion of the room.

he did it. it worked.

hot air was gathering in the top.. it had nowhere to go but compact
itself back down into the living space. which made his stand alone wall
ac work harder.. in fact.. it wasn't doing the job UNTIILL he removed
the cumulative hot air from the upper portion of the sunroom.

now his ac cuts off and on. it cools the room just fine.

why cool the upper portion of a room when you do not use that part of
the room.

my theory is... don't stir the air around. EXCEPT in the winter.

in the winter all you warm air is on the ceiling... so it needs to be
directed back down to where you can feel it.

it's just the opposite, you wants to have ventilation that allows
sinking cold air to escape... it's just like water, cold air will
settle to the lowest spot so cut a hole in the floor at the lowest
spot..and put a vent there to allow the cold air to escape.
(i think im just kidding about that...)...

we'll talk about that when winter gets here