I took the trouble to find all of Dukes threads from the last three months in the Energy, Heating, and Insulation folder, and extracted and collated all the relevant Data from them. The big bold lines are thread titles, the blue, bracketed comments are mine.
Duke, After reading everything and looking at most of your pictures, here’s my DIY advice:
1. Buy some 1 1/2″ foamboard insulation and fill that hole in the bedroom wall! Great Stuf the edges.
2. Reroute all the ductwork so it lays down on the ceiling under the blown-in. Add some 6″ FG insulation, paper side up, over the ducts, because the blown-in won’t cover as well as it does the flat ceiling. Pile the blown-in over the FG edges to seal them together. Check that all joints are sealed and that there are no holes in the ducts. If any of the hanger pinches don’t come back to round, cut the duct and insert a coupler. Avoid sharp turns.
Temporarily remove the unused ducts from the plenums and seal the plenum connections.
Use water heater blankets or similar to wrap the ductworks that go from the top of the air handler down into the blown-in. Add 1″ foamboard to the sides of the metal plenums. Seal those edges.
3. Put some dust filters at the return registers until you get the house sealed and there isn’t as much dust in the house.
4. Seal all exterior wall and top floor ceiling penetrations and openings.
5. After you complete 4, have a company come in and clean all the ducts.
1, 2, and 3 are just to “perfect” your system so it will work as well as possible. 4 is to reduce the heat load on the system and the amount of dust in the house.
Remember that you are losing 1 ton of cooling from the ductwork alone. Much of this loss is because all your ducts are now stuck up in the hottest part of the attic. Putting them under the attic floor insulation will place them more inside the conditioned envelope. That, plus adding insulation to those parts that can’t be brought into the conditioned envelope should recapture that 1 ton of current loss.
You’ve had several techs add a pound or two of freon. They were idiots. You need to have a real AC tech come in and check the pressures in your system to determine the actual freon content. You may be overloaded now, and that is just as bad or worse, than not having enough.
Begin Data recap:
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Temp difference between attic and floor
Last year I started monitoring the temperatures in my attic and the second floor of my home… I then sat the base unit in the bedroom I use as an office and the remote unit I placed just inside the attic at the folding ladder that would be the lowest elevation in the attic that was unobstructed of air movement… when the attic was 95¦F the temp in this room was 80¦F
I’ve been complaining for five years at how poorly the upstairs cooling system is
14″ of insulation in the attic
My 2nd floor temps
The room that is getting overly hot was just discovered why it is getting overly hot. Underneath the twin double-hung windows the wall is open (another problem being that reason). The OSB sheathing which sits behind the brick facade is reaching 88-91¦F on the interior side.
The 1st floor zone HVAC resides in the basement, and the 2nd floor zone in the attic. Both zoned systems employ flex-duct (hate it) and are installed along the home’s centerline
air filters are replaced every 60-days even though they are rated for more. Inspection of an out-going filter isn’t terrible
Baseline AC is $3793 for 1000 SqFt Zone
He said the two-ton upstairs zone covering ~1,000 Square feet is “running properly, but he noted the refrigerent pressure was a couple of pounds low.”[Noticed?!?!?!?]
There are two openings to the first floor: foyer and family room.
he master bedroom suite has four source vents (bedroom, bath, water closet, and closet) and only one return
HVAC technician said there was a 21¦F differential between air entering the AC system (warm side of evaporator) and leaving it.
~10¦F difference at the coolest room’s source/return vents.
It is 15¦F cooler outside at this moment (and in my attic) than it is in this bedroom that I have converted into an office. And no, nothing had been running during the night in this room.
Problems identified were the house was leaking like an overworked hooker. Evidence of filtering dust at every duct connection at the plenum, and ever floor/ceiling supply and return register was shown. Yikes! The recommended number of whole-house air exchanges was 7.1, but mine was doing 13.5. Estimated cooling loss was 25% (1.24 tons), and the biggest offenders were the registers themselves.
my 1st floor has a 3-ton unit. No wonder it cools without effort.
there are other natural openings in the envelope that leak in excess.
there are other natural openings in the envelope that leak in excess.
Then there is the three-year old nobody can fix for any dollar problem with the wife’s study and upstairs bedroom window… wall and ceiling completely open to the brick-OSB air gap.
Pictures: 91947.44-46, 58, 66-68
http://forums.taunton.com/tp-breaktime/messages?msg=91947.44
[All duct work is hung at top of attic! Most are pinched by hangers!]
All bedrooms have a single supply and single return. The master bath, its water closet, and the closet beyond them all have supplies and no returns. There is also J&J bath with a returnless supply, and a third full bath with a supply and no return.
I see plenty of dust accumulating at the returns.
Auditing the Energy Auditor
the first floor I have both a supply and return uncoupled and their flex-ducts sealed, but the supply and return registers are completely open to the basement below. Taking a CFM measurement reveals >60 CFM (Cubic Feet per Minute) ‘”leakage”‘ according to the person performing this audit.
Additionally, I have the ceiling for the study’s bay window completely opened up.
the bedroom directly above the study to have its exterior wall drywall opened up just below the window itself.
currently have a 25% cooling loss and 31″ heating loss due to the collective measured ‘”leakage’s”
The auditor performed a per register CFM test, and claimed that the loss due to ‘”leakage”‘ should be zero (0). Ok, but then he admits the measuring device cannot measure below 7.5 CFM.
No attempt to determine any ‘”leakage”‘ at the plenums was conducted.
is the air pathways in an HVAC designed to be 100% sealed (i.e. a closed system)? [Yes, but it might not be built that way.]
First floor has one return and one supply disconnected due to construction in the basement, but I had not a problem with the first floor system in its ability to ‘cool’.
two tests were performed. The first one was the blower door test, which was skewed, IMO, due to the aforementioned damages leading to large leakage’s themselves. The second test was to essentially place a negative pressure on the inside of the house and measure air flow out of a supply/return register using a manometer.
The second floor was stated to have the worse leakage’s in the coolest room, which had the farthest runs from the evaporator coil. The room with the shortest run is also the warmest room facing NE, and is above the first floor room with said damage.
The worse leakage’s for the second floor are less than half the measured rates for the disconnected supply/return registers on the 1st floor.
The 60-CFM leakage’s were from two disconnected registers, which were to be re-connected. The worse disconnected register was 30, in the master bedroom, which is the farthest run from the HVAC, and also the coolest room on the 2nd floor. All other registers measured below this.
The device they used at the registers was nothing more than a shroud with a fan-meter on it… the fan kept shutting off during the per-register manometer test.
Its getting hotter and the AC man says
I’ve got dang near 1-kW worth of heat-producing electronics in the mini home theater, and another 1.5-kW worth of heat producing computer electronics in another room… I have not used the mini home theater, and its completely unplugged. Only one PC upstairs is used in the present condition, and its shut off after checking email/forums, etc.
The first HVAC contractor stated the delta was 21¦F.
But even with it [AC] running constantly it has not dropped below 75-76¦ in a couple of weeks.
the first HVAC contractor… he didn’t even have a working detector on hand to check for refrigerant leaks–yet he “added a couple of pounds of freon
[House description at 93345.62]
The 1st floor has a basement located 3-ton unit, and the 2nd floor has an attic located 2-ton unit. The 1st floor has about 1326 SqFt, and the 2nd floor 1229 SqFt. Last HVAC contractor used a “safe rule of thumb of 500SqFt per ton” but said nothing about migrating heat loads.
The 21¦F delta was at the plenum. The 10¦ delta with between the supply and return registers of all rooms.
f the AC is dropping the outside air from 93¦F to 83¦F
[AC cools and recycles inside air]
The condenser fans are clean, not blocked, and weeds kept at bay.
think you are forgetting that heat is still being added while the HVAC is attempting to remove it. For instance, if the room temp is 83¦ then its 87¦F when it reaches the plenum because its being heated on the way back. [What is the return air temp at the return register?]
93345.65 in reply to 93345.64
Presently, it is ~70¦F outside and in my attic. I just turned on one PC (this one) and in this 2nd floor computer room it is 79¦F. Of course, this is a NE facing room, and the coolest room is SE and 4¦F lower. Thermostat is set to 73¦F, but it will never reach that temp at the thermostat. Impossible.
“even with loss to 10 if I’m drawing 83 degree I should be getting mid 70s.” I think you are forgetting that heat is still being added while the HVAC is attempting to remove it. For instance, if the room temp is 83¦ then its 87¦F when it reaches the plenum because its being heated on the way back.
Remember, its was 93¦F outside, and if I shut off the AC the temp will climb fast. Of course, the distribution of condition air within a room could be a problem as well. It wouldn’t surprise me that a ceiling fan could mix the warm and cool air better.
The insulation in the attic is 12-14″ of pink loose Corning fiberglass. I have no idea what the blower CFM rating is, nor how to find that out
Bought house in December 2000… 2006 the marginal 2nd floor conditions became insufficient, and now are totally incapable…
now are totally incapable even after “adding a couple of pounds of freon” this season.
The [3] 1st floor 3-ton returns
instead of per-room style returns (like what the 2nd floor has).
All attic flex duct is suspended until the strike the roof rafters, and then travel down the rafters to the supply registers at the exterior wall openings (windows/doors). All are reported to be 8″ in diameter.
The lines for both units were changed.
Ok, so someone FINALLY told me that the 1st floor heat loads for two-story rooms is migrated to the 2nd floor’s total heat load. [Only the excess heat that the first floor AC can’t handle. If the 1stF AC fully cools the air, no heat load goes up.]
attic where the refrigerant lines come into a ‘box’ the tag–which is fairly well hidden by the mastic–reads: ‘BVR24 24-A**’ 24,000 BTU R-22, 350PSI. Similarly, the basement unit read ‘BV124 30-1CN22VER3W’ 36,000 BTU R-22, 350PSI.
in the attic. On the left-side of where the refrigerant line comes into this evaporator coil box there is staining, a little condensation, and a portion of the box’s wall facing me is cold to the touch while the rest (side walls, etc.) is not.
the two condenser units outside are Lennox (but the evaporator coils are Trane!?!) 10 ACB36-11P and 10ACB24-9P.
I then traced the 1st floor evaporator refrigerant lines to the 10 ACB36-11P unit.
SamT
Replies
Nice job of getting all the goodies in one place.
What's with this http://forums.taunton.com/n/mb/at.asp?webtag=tp-breaktime&guid=2F55C6DD-2C73-40F3-889C-2345D624324C&frames=no I can't figure out the ? optical illusion or is it pinched real tight to make the corner angle? it almost looks like it stops and starts at that point.
I looked thru the photos and couldn't see any sign of supply for the roof turtle vents.
If it's not being moved that will be a big part of the load acumulation up there in the attic.130 degree+
And it sure would be nice to have a strap on the bvent diagonal. to the and out the roof.
I'm outta boots to change. Been kicking the dead horse to long.