Actually, the total load calculated for the system by the energy star rater was 2.5 and, (and if memory serves that was with a small round up).

I'm not "assuming" anything. I've been told that the unit is oversized by a contractor who tested it along side the WaterFurnace territory manager. They spent two hours running tests on the equipment. The contractor chose his words very carefully in the letter I asked him to write. But he looked me in the eye and told me the unit was oversized. Two different energy star raters know this house and the equipment. They both say it is grossly oversized. I wish it wasn't the case. But it is.

Is this correct?
Let's assume the energy star rating was 2.3 tons for argument sake. If 1st stage is 2.8 tons then there is a .5 ton difference. .5/2.3=roughly 21.7% oversized for 1st stage. With fan speed, and other tweaks, shouldn't the system be ok (not great, but ok) for dehumidification in 1st stage?

Joe, do I recall you saying that zoning can be difficult to get right, or something to that effect?

At least, I assume, aux won't be needed for the coldest winters.

MPH, what temperature setting did you use in the summer for day/night? When we keep our house on the warm side (75-76 degrees) our unit doesn't run very much and indoor humidity is higher.

I really appreciate the effort here. My thermostat setting during the summer was at 72--sometimes lower just to get some of the humidity out of the air. :o)

4 zones will almost certainly demand a bypass or dump zone, especially since unit is oversized.

Are you absolutely positive that only low stage is coming on?

What do you mean by a dump zone?

a few points

4 zones is a significant contributer to the short cycling ( joining some zones together may be a start )
roughly 75% RH in the crawl space is an issue well worth adressing independent of the fact it is a MAJOR contributing factor to the homes humidity issue
" It does 1st stage -- just not for very long " in your situation I would strongly consider disabling 2nd stage alltogether or setting it up to only run when specificly asked for .
As well as not running continues fan as engineer pointed out limiting or eliminating the post purge fan time will also help
"dump zone = an area(s) of the home where you dump the extra air , (there because your zoneing system is varying the overall duct size) so the air is not being pushed with as much speed and volume to the area calling , when having the system run longer is the name of the game it will help , but it sounds like the "adjusting zone damper setting " allready addressed that by setting the dampers to not close all the way , could be wrong there though just a guess.

So you don't have a thread on your particular situation or answers to fundemental questions, you just want to squawk in the middle of someone else's thread.
A lot of intelligent and well meaning people are here to help.
Why don't you look up "help us help you", start a thread answer some questions and we might be able too.
j

It is a simple matter to mount a hand switch between Intellizone's Y2 output and the unit's y2 input. That'll stop the compressor from upstaging although the blower will still ramp up - hence my suggestion to use 5 lowest dip switch settings for CFM.

Joe,

I posted on this particular thread because it was subject appropriate. I know a lot more about my hvac system than most people but I'm not an expert. I trusted the experts. I've had the experts out here and they've diagnosed the problem for me. I think I have answered most of the questions asked. There are other answers but those would be in the hands of the gentleman who ran the tests and he will not return them to me. I'm not inclined to perform the tests myself. I really wouldn't know where to begin. I'm a homeowner. I'm not supposed to be the expert. I am thankful that I had the good sense to start monitoring my humidity levels. Most homeowners don't do that -- which is probably why most don't realize they have some of the same problems I do. I will certainly gather up all of the thoughts and suggestions posted here and bounce them off of the people I work with to solve the problem.

A few points to keep in mind:
1. A load calculation is just an estimate - it is not a perfect number. And it depends upon the temperatures used (outside and set point).
2. A load of 2.5 tons means this is the peak requirement for about 98% of the time. Therefore if the load was 2.5 tons and they installed a 2.5 ton unit you still have an oversized unit except for the hottest part of the hottest days of the year (and yes, on two days of the year you probably have a slighly undersized unit).
3. Studies do not confirm the belief that perfectly sized units dehumidify better than oversized units. A study by FL solar actually found that after installing new units based upon manual J calculations (most new units were 0.5 to 1.0 tons smaller) that the interior humidity actually increased ever so slightly.
4. A larger unit has a larger latent heat removal ability (i.e. provides more dehumidification) per minute of run time. This is the overlooked factor. For example, a 4 ton unit removes about twice as much water as a 2 ton unit per minute of run time. The 4 ton unit runs 1/2 as long. Therefore, the humidity removal is practically the same.

If your house is running at a slightly negative pressure then you are probably pulling in more humidity than you realize. Quite possibly you are drawing air up through your floor which might even be more humid than outside air - especially if you are irrigating your yard.

If I were the dealer here are the questions I would ask. If I replace your 4 ton unit with a 2.5 ton unit and you still have humidity problems are you going to pay me for the costs or do you expect me to just eat them? And are you then going to be happy when in the middle of summer you get hot or are you going to call me again complaining that the unit is not working properly?

If you have spent as much as you say ($25K I think) then go talk to an attorney and ask him to draft a letter demanding satisfaction. Have him send the letter to both the installer and the manufacturer and the BBB. This should cost you between $50 and $75 at most.

It really sounds like you are going to need a dehumidification unit - no matter what size unit you have installed.

I don't have a dog in the hunt but thats my take. Best of luck what ever you decide to do (and my apologies to the thread owner for joining in this slightly off topic discussion).

Alex

Just to clarify, I did some checking on the report that Alex mentioned. I had not heard about the study or anything that suggests that larger units dehumidify better than smaller ones--so this really concerned me.

Alex noted:
"3. Studies do not confirm the belief that perfectly sized units dehumidify better than oversized units. A study by FL solar actually found that after installing new units based upon manual J calculations (most new units were 0.5 to 1.0 tons smaller) that the interior humidity actually increased ever so slightly. "

However, after looking into it, I don't think this really applies to my home which is brand new. For one thing, I believe this study was on much, much older homes in Florida with really leaky ducts and from my understanding, that was shown to be the real culprit. As part of my Energy Star package, my ducts were tested for leakage and performed extremely well so I don't think I would experience the same penalties for a properly sized system.