American Standard indoor coil problem ?

[beenthere]

Yes, and yes.

[johncavh]

HO stated return air temp. at wall grille 64 that seems a bit low if stat is set to main 74

[beenthere]

In the first post, it was 77, so I took th 67 as a typo.

[2elaines]

beenthere, post stating 64* at intake is not a typo. I am using a refrigeration
thermometer with about a 5" stem on it and pushing it thru the cheap fiberglass filter. The ubit does have a 5" media filter upstairs, I do not rely on cheap fiberglass filter alone.

I will post size, length of ducts in a little while.

Here are some specs from today.

thermostat left at 74* all day.
82* outside - intake 64* - rm1 76* in room w/58* at register,
rm 2 73* in room w/56* at register, rm3 74* in room w/58* at register

95* outside - intake 65* - rm 1 76* in room w/51* at register,
rm 2 73* in room w/58* at register, rm 3 77* in room w/62* at register.

Room 2 seamed to get better ??

Thanks

[beenthere]

Sounds like some supply air is traveling across teh ceiling and into the return.

Remove your 1" filter and try it that way for the weekend.
2 air filters in series can slow the air down more then you think.

[2elaines]

Thanks beenthere, I will remove fiberglass filters.

Here are the approx. duct sizes. I don't envy you guys crawling around in an attic ! When the new unit was installed the hard pipe was cut back and hooked to plenum with flex. Approx lengths include the flex.

36' of 12" hardpipe serving 1 register to kitchen
36' of 16" hardpipe serving 3 registers to den & dining room
25' of 12" hardpipe serving 2 resisters to bedroom & bath
12' of 12" hardpipe serving 1 register to bedroom with Y of 7' of 8" to bath
45' of 5" flex serving 1 register to washroom
6' of 7" flex serving 1 register to bedroom
20' of 9" flex with the triangle box then 5' of 7" to bedroom & 25' of 7" to office

1 20 x 30 hall return & 1 14 x 25 ceiling return

All I know about cfm is installer told me 400cfm per ton x 4 ton = 1600cfm
Home is 1950 sq ft

[beenthere]

The air extra filters out will help alittle. Maybe enough.
With the majority of your system being hard piped. The flex runs are alittle too restrictive for the air flow you need.

[2elaines]

The air extra filters out will help alittle. Maybe enough.
With the majority of your system being hard piped. The flex runs are alittle too restrictive for the air flow you need.

Does this mean the flex is undersized ?

I took the filters out for now. Will see if that helps.

Thanks

[beenthere]

Not so much undersized for the amount of air needed. As much as for the size of the existing hard ducts. With dampers installed and the hard pipe runs balanced, the flex runs would work fine.

See how it does for you this weekend.

[Mr Bill]

Well according to my air duct calculator @.1 static you have enough duct sizes to provide for over 4000 cfm's of air, the air velocity must be terrible especially with those long runs, but at least your volume is good.

36' of 12" hardpipe serving 1 register to kitchen = 700 cfm's
36' of 16" hardpipe serving 3 registers to den & dining room =1500 cfm's
25' of 12" hardpipe serving 2 resisters to bedroom & bath =700 cfm's
12' of 12" hardpipe serving 1 register to bedroom with Y of 7' of 8" to bath = 700 cfm's
45' of 5" flex serving 1 register to washroom = 70 cfm's
6' of 7" flex serving 1 register to bedroom = 150 cfm's
20' of 9" flex =300 cfm's

[2elaines]

Does all this mean my hardpipe is hogging all the air and not letting the flex get what it needs ?

[beenthere]

Air takes the path of least resistance. So without balancing dampers, yes.

[accutrol]

It means that you have very little static pressure in your duct system. If you put 1600 cfm's into a duct system that will carry 4000 cfm's, by the time that the air gets to the registers, there is no air. I would really like to see the numbers that are produced if the system is tested with a hood at the registers.