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Posted by a student on August 30, 2006, 11:55 am
udarrell wrote:
> a student wrote:
>
> >I have a LR which, on hot days, remains 5-10 deg hotter than the rest
> >of the house. The A/C is capable of cooling the LR, but that makes the
> >rest of the house uncomfortably cool. If you close the registers in an
> >effort to direct more air to the LR, it causes a lot of noise at the
> >registers as airflow is very strong everywhere except the LR.
> >
> >The LR is twice as big as the next largest room in the house, and has
> >two registers. All other rooms have one. The LR registers are twice as
> >far from the blower as the rest of the registers. The air flow is
> >noticeably reduced at the LR registers when compared to other registers
> >in the house and the temperature at the LR registers is also 2-5
> >degrees higher.
> >
> >
> If no dampers in ducts, install them to help you balance the airflow.
>
> >The LR registers collectively share exclusive access the same trunk.
> >There are no significant leaks, but the duct path could be straigter
> >and some excess length could be trimmed (currently just compressed).
> >However, I do not believe straighting and fitting will sufficiently
> >improve the situation.
> >
> >There is a header between the LR and the return which prevent efficient
> >return of hot air in the LR. There is a fan in the LR but it helps
> >little.
> >
> >The LR is also the hottest room in the house due to windows, exterior
> >walls, and smaller attic space.
> >
> >The A/C unit also appears to be oversized - typically on hot days the
> >cycle is only 8 minutes - on for 8, off for 8.
> >
> >
> It is horrendously oversized! That is terrible!
> It takes 5 minutes to achieve near its efficient running capacity.
> What can be done with a little half-ton room A/C, over 900-sq.ft.
> http://www.udarrell.com/airconditioner_current_temperature_btuh_charting.html
>
>
> >My thought at this point is to increase the size of the duct (trunk and
> >both branches) in order to increase airflow to the LR. Currently there
> >are four 8" trunks coming from the blower, each with two 6" branches. I
> >am proposing to increase the LR trunk to 12" and branches to 8".
> >
> >Am I on the right track?
> >
> >TIA,
> >chris
> >
> >
> A real good "Return Air" in the LR & dampers should help!
> Here is some info on ductwork. - udarrell
>
http://www.udarrell.com/proper_cfm_btuh_duct_sizing_air_conditioning_systems.html
>
>
> --
> Air Conditioning's Affordable Path to the "Human Comfort Zone Goal"
> http://www.udarrell.com/udarrell-air-conditioning.html
Daryl, thanks for the advice. Your website is very informative!! Much
more useful than most of the stuff I have come across on the web.
I can see now that the return is more of a problem than the supply in
this case, and it does seem like dampers would help.
Obviously the ACCA manuals are a preferred reference source, and I see
you mentioned ARI texts on your site...any other reading materials you
recoomend?
Thanks again,
Chris
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