Four Different Manual J's - Same Recommendations!

[54regcab]

Nope, if the duct work is bad/poorly designed no fancy equipment will overcome that. I'm a BIG fan of using mid level equipment that's correctly sized (or even a little "undersized" since manual J typically oversizes). Use the difference in price to fix ductwork/home envelope. Overall energy bills will end up being lower and you will have better comfort.

Once you get into the 2 stage equipment (which accounts for less than 10% of what's installed in our area) parts tend to become expensive special order items and only the best techs are good enough to work on them. Getting people to move up from the builder grade stuff is hard enough, high end equipment is a tough sell. Not sure how much 2 stage stuff is typically installed in your area.

[Florida Joy]

Once you get into the 2 stage equipment (which accounts for less than 10% of what's installed in our area) parts tend to become expensive special order items and only the best techs are good enough to work on them. Getting people to move up from the builder grade stuff is hard enough, high end equipment is a tough sell. Not sure how much 2 stage stuff is typically installed in your area.

I've had different contractors tell me different things... probably based mostly on what they'd like to sell me! Some (especially the Trane dealers) said one or more of their 2-stage offerings is "most popular", by far. Others said they rarely sell the 2-stage equipment these days since the IRS tax credits expired. I tend to believe the latter. I have a variety of quotes on 2-stage and the less expensive 15 SEER units and I've searched through the county's online permit site to get a feel for who's installed which units in my neighborhood over the past year. While the site doesn't reveal model numbers, it does show the cost estimate for the job. Looks to me like the higher cost 2-stage installs have been few and far between over the past year, regardless of what the dealers would like me to believe!

Checking dealer permits also gives me an idea of which of the one-man shops are in this business for beer money only!

[tedkidd]

You didnt have zoning before, and based upon all youve written, not sure where the benefit would be. I suspect it was offered as "you could do" rather than "you need to do."

It's very likely multi stage or modulating will blow your mind. Continuous operation tends to solve all but extreme load imbalance issues. There arent multiple occupants with varying temperature requirements.

Why don't you do the equipment and see if further efforts are warranted. I bet they won't be.

[Florida Joy]

You didnt have zoning before, and based upon all youve written, not sure where the benefit would be. I suspect it was offered as "you could do" rather than "you need to do."

I agree on lack of benefit. On re-reading the email offering to sell me the Greenspeed in combination with zoning, it sounds like he's looking to install them together so I won't "notice" temperature differences, like I do now. It appears his objective, besides profit motive, may be not having to address the duct "tweaking" i'd like him to do during the install. Is it really that much work to put in a couple of hand dampers?

[54regcab]

Contractors don't like messing with ductwork. It's labor intensive and has one of the lowest profit margins. Repairing bad ductwork will make a bigger difference in comfort than just about any other home improvement you can do.

[tedkidd]

No adjustment at the registers? You can get better registers, then avoid introducing penetrations and possible leakage points. Sounds like you have tight ducts, and youll want to keep it that way.

[Florida Joy]

No adjustment at the registers? You can get better registers, then avoid introducing penetrations and possible leakage points. Sounds like you have tight ducts, and youll want to keep it that way.

Hmmm... I'll take that into consideration... don't want to run the risk of messing with already "tight ducts". I did install new Hart & Cooley registers and adjusted them down quite a bit. Amazingly, that did send more air to the back of the house and lowered the front to back delta to about 2*. But you can still hear the air coming from the registers when you're in the 2 b/r's closest to the plenum, whereas the other registers in the house are virtually silent. I was hoping dampers would silence these registers and allow them to be opened all the way. I suppose I could have FPL do another duct leak test for $30 after the dampers are installed, and if they leak too much, have FPL insist that the contractor re-seal at his expense. Most installers are also on the FPL PIC list for duct sealing and I'm guessing they don't like customers complaining about their work to FPL.

Is there any ill-effect on the equipment by restricting airflow at the register?

[54regcab]

The only Ill effect I could see is if the ductwork is marginal to begin with. Equipment needs 400CFM per ton and efficiency suffers if it isn't there. Closing close registers raises the overall static pressure and reduces CFM and/or will make a variable speed blower work harder. Smaller equipment requires less ductwork/airflow and closing registers will have less of an effect.

[energy star]

You may wish to be less vocal and descriptive about the HVAC contractors in your area. You may find it difficult to find someone who is willing to work for you.

[behappy]

1827sf Central Florida East Coast lots & lots of single pane sliding glass

Why don't you consider doing something with your windows. Single pane windows are a BIG heat gain.
Then you will get down to the 3 ton level that you want?

BTW I live about in the same heat gain area and have a 3 ton with plenty of left over cooling ability.
Just chec your heat gains...