Could use some advice.  Apologize in advance for rambling.

Existing A/C has died.  Since entire HVAC is 17 yrs old, am replacing entire system.  Currently have an 80% (a real stretch) NG and 2.5 Ton 8 SEER A/C.  I have several questions that I would love some advice on.

The existing system has heated the house just fine, albeit quite expensively.  The house is 17 years, 2050 Sq ft, 2-story, located in Cincinnati area;  I would suspect average heating/cooling requirements as the climate, on average, is not extreme for heating & A/C requirements.  A/C has never been able to keep the house comfortable.

Replaced windows (17 windows, 9 of which are 6 feet tall!) with 3-pane, e-glass, etc.  My gas bill decreased by over 40% this winter just from the window change.

Have had several estimates for replacement.  I am comparing 95% NG and A/C, 95% NG and 15.5 SEER HP dual, and Geo (Waterfurnace/Climatemaster).

The most interesting aspect of research was trying to schedule appointments through websites.  I work nights so daytime phone calls aren't the most convenient.  Shockingly, had 3 really beautiful proposals in binders show up at my house from supposedly reputable installers without anyone having been in my house.  These were "guaranteed estimates."  Needless to say, these folks have been crossed off my list.

The cost to operate dual vs. geo seem closer than I thought.  However, the 30% federal tax credits along with state/local credits/rebates of $3500 make the geo systems extremely competitve.  I am leaning geo to decrease my family's carbon footprint but still want to make an informed choice.  Several reputable installers, even those who do not deal with geo, suggest that the geo systems should last longer than traditional furnaces when properly installed/maintained.

The best advice I have received so far came from an company that doesn't install geo.  This gentleman was a former engineer who started his own company 18 yrs ago.  Though he sent a formal proposal at a later date, his "gutshot" estimates of demand vs. loss, etc were spot-on to the formal proposals I have received. He also pointed out several flaws in the existing ducting set-up and gave me several suggestions for improvements that any installer should address without my pointing them out first.  He asked if I had had problems with differences in temps between floors.  He suggested this could possibly be addressed through restricting some of the return air vents (one in every room) on first floor, thus improving air exchange and balancing temp.  Obviously least expensive option.  Don't know yet if this would work.   Really wish this guy did geo!

Have had several estimates for all systems.  Have the geo systems down to a choice of 2.  Here is where I need some help.

System #1: geo estimate recommends Climatemaster 27, 3-Ton.  Got all the analysis.  Initial analysis called for 2.5 ton but I requested a 3-Ton due to sleeping upstairs during the day and the old system never keeping up with demand.  Company said that 3-Ton wouldn't cause a problem.  Very impressed with the analysis and reps.  However, had no real solutions for the difference in temps between the upstairs and downstairs.  This company uses a 3rd party driller.  They want to do a blower/door test, which of course, I am going to do.  They didn't allow for new windows in determining demand.

System #2: geo estimate has not been quite finished yet, but their initial analysis is for a Waterfurnace, 4 Ton.  They also will do blower/door test.  Recommended same ductwork changes that non-geo company did.  Recommended zoning to address upstair/downstair temp differences.  Their engineer will be back and will calculate based on better windows.  They use their own drillers.

To me, this is not a Climatemaster vs. Waterfurnace question.  I am concerned about the engineering of the install as I believe that makes up 90% of the success/comfort of the system.  I am assuming the engineer for #2 will back down the size to 3-Ton.  If not, install price will increase due to need for 4th well.

My questions are these:

1.  Even though the tax credits get geothermal within a couple of thousand dollars of the dual fuel, are the operating costs of the geo low enough to justify the price difference?

2.  If System #2 is over-sized, will it operate less efficiently?  Will it take dehumidify enough?  Can geo systems be set at a certain dehumidifying level to dehumidify even when the home is at an acceptable coolness?

3.  Zoning the duct work (thermostat on each floor):  I understand the concept, but haven't gotten estimate on price.  I'm assuming 400-600 per "trunk".  However, all bedroom doors are closed when everyone's in bed.  Should the thermostat be placed in the largest bedroom?  There are no registers or return air vents in the hallway.  If the thermostat was placed in the hallway and the doors are closed, wouldn't I get a "false" temperature reading.  At the same time, would restricting return air flow from main floor have the desired effect of increasing air exchange with upstairs, thus making each floor more equal in temp?  This would alleviate the need for zoning.

So appreciative to all the experts who have answered questions for novices like me.  I have learned a great deal on this sight and have been learning to ask the right questions.

Like everyone, this is a huge purchase for me.  For the money, I want to be comfortable while making as informed a choice as I possibly can.

Waiting for answer on a 2nd on the house, so have a couple of weeks to think before making final decision. 

Thanks in advance for any guidance,

Oldscholar

To throw another option into the mix - keep your NG furnace in place for peak loads and go down to 2 or 2.5 tons for the geo. Also do some insulation and sealing upgrades. The quotes should include estimated operating costs/payback info.

Welcome to the forum!

It would help if you give us the actual details of the analysis, so we can advise you better.

1) Obviously we are very bias here, but if you are looking at replacing the existing system anyway, geo usually pays of relatively quickly. You should have gotten the analysis which compares the different fuel sources.
2) Not always, since it will turn on less, but yes, most of a time. The big difference is the increased upfront cost, less comfort and the negative effect of shot cycling on the equipment.
3) If done correctly, you never regret zoning, especially between floors. Thermostat should be placed in the bedroom you use most, not the hallway. While it is desirable to balance airflow, heating and cooling season have different dynamics, since heat raises, so you need less heat capacity upstairs but more cooling capacity. If you have the extra money, it is well spend on zoning.

Thanks for the advice.  Looked at the official proposal for System #1 for the numbers.  The analysis that i was told was there, is not.  Contacted vendor and they said it was only an estimated proposal and that they would give a complete analysis after the blower test.  I hadn't even looked past the proposed equipment yet.  Was waiting for the proposal for System #2 so that I would have something to compare it to.

Will update after I get more info.

Thanks again,

Oldscholar

What is the cost of NG and electric in your area?

If done correctly, you never regret zoning, especially between floors

This seems to be a big "if". Make sure turned off zones don't create a low total airflow situation, make sure both supply and return registers remain balanced (even when a supply duct is off). Don't cause short cycling. Far easier to get right using hydronics with a buffer tank.

Far easier to get right using hydronics with a buffer tank.

Jonr,
Could you describe this more - or point me to a link about it?

It seems to me that I would be well served with more zoning for my
second floor....the rooms are different sizes, some face South, some North.....
...and I thought that small hydronic air handlers would
be available, but have not seen info on them (like a mini-split for water?)

Thanks
Seth

http://www.multiaqua.com/pdf09/Multiaqua09_MHWW.pdf

Hydronic air handlers, they work very nicely with geo. I am very impressed with the ones we have installed.

In terms of hydronics, it is much easier to push water around and create zone than with forced air.

Hydronics make it easy to use a buffer tank - so the boiler or geo unit can run when it wants, at the flow it prefers and for a reasonable time period. Then use of the heat is a separate issue and can be done as fast or slow as you want - a single zone using just a little is fine.

With air, you have the issue of "only one zone wants heat and yet the geo unit needs a full x CFM (hard to do with just the small ducts going to/from the one zone) and will produce 48,000 btu/hr" (so it will heat up the small zone very quickly and then short cycle).

In terms of hydronics, it is much easier to push water around and create zone than with forced air.

Hydronics make it easy to use a buffer tank - so the boiler or geo unit can run when it wants,

Thanks to both of you - that's what I am looking for.

Seth

Thought I had posted, try again.

Oldscholar the OP is best served by water to air.
Introducing a hydronic air handler and buffer might be a good idea where radiant is present, but not here.

2 stage water to air units work well to reduce minimum airflow requirements where ducts are zoned.

Just reducing flow through return side ducts is not the answer to balance betweem floors and I might be skeptical of the "former engineer" who suggested it.
I also want to mention that duct zone systems are more likely to be thousands installed with duct modifications, not 100's.

j