Hi, Thanks very much for your responses. - Everyone I've spoken with, and you've confirmed, that one zone per floor makes sense. If I'm missing anything else about "zones", please let me know! - How much should it cost to go from 2 zones to 4? - We are definitely going to put in all new ductwork. Is there anything here that I should be aware about or ask for? Any sites (besides GW) to get more knowledge on this area so I can ensure we get the ducts sized properly? - Good comments on getting more info on the geo wells, piping, etc. Will do. - Can I get a Manual J done even if the house is under construction? Framing is almost done, but the exterior work is not complete, and so it's open to the elements right now. - Yes, we have a natural gas furnace and electric AC in the house. It appears that a NG furnace was installed in 2007. The unit is a Lennox Signature Collection, model CX34-62D-6F. We also have an electric hot water heater, AO Smith ProMax Plus, model FCG 75 300. Does it make sense to re-use these or upgrade? Obviously, the furnace will be out if we go with geo. - Here's a summary of our NG and electricity rates. I hope I'm doing this correctly -- taking the bill amount and dividing by the energy used. Some months may need to be taken out because the numbers are too high/low. Please note that we have not lived in the house, so this is what we were paying for several months before construction commenced. So I would expect actual usage, and thus our bills, to be higher, but I guess that the cost per unit would be somewhat proportional. Natural Gas Monthly Charge / Therms Used / All-In Cost Per Therm $18.06 / 5.1 / $3.54 $16.76 / 5.1 / $3.29 $51.90 / 32.5 / $1.60 $78.53 / 57.7 / $1.36 $339.62 / 314.7 / $1.08 $362.71 / 321.1 / $1.13 $184.41 / 154.8 / $1.19 $81.98 / 60.4 / $1.36 $66.62 / 47.4 / $1.41 $18.45 / 7.1 / $2.60 $16.18 / 5.1 / $3.17 $1.97 average Electricity Monthly Charge / KWH Used / All-In Cost Per KWH $285.18 / 1757 / $0.16 $137.36 / 786 / $0.17 $77.44 / 416 / $0.19 $57.91 / 316 / $0.18 $66.29 / 382 / $0.17 $86.87 / 524 / $0.17 $61.02 / 341 / $0.18 $24.50 / 76 / $0.32 $25.22 / 80 / $0.32 $38.34 / 73 / $0.53 $21.23 / 53 / $0.40 $32.62 / 140 / $0.23 $0.25 average - It must not be code on my state (MD) to have each floor zoned. Our bids have been for two zones (on per system, one system covering basement and first floor, second system covering second and third floors), or for four zones (running off two systems). - Thanks for the heads up on the tax credits. My husband is tracking these, so I'll make sure he knows this. - The addition is on a loggia, not crawl space. So the basement is a walk-out basement, and the loggia will in effect extend the basement, and then the kitchen/family room addition will be above this, and our master bedroom addition above that. It's at the back of the house. Here's an early photo so you get the idea. The house is brick, and the addition will be part brick, part clapboard. - I am trying to learn what an HRV is, so am looking into this. - If it's not a good idea to go with spray foam insulation, let me know! Thanks for the info on what type would be good. - More thoughts on what system to go with, pricing, etc.?? THANKS AGAIN!!

I don't understand the concept of why the low stage can't be used in a dual fuel situation. Let's say is 20 degrees outside and it is more efficient to heat with the gas furnace than the heat pump. The Infinity furnace will use its low stage to try the maintain the set point in the house. It is going to cycle on and off to try to maintain the house at 70 degrees. This is what it does in my house. The Carrier Infinity 58MVB060 has two stages and cost about $200 less than than the three stage 58MVC060. However the 58MVB has a high and low stage, and no middle stage. So in effect you still have a furnace with a low stage. I am not an expert when it comes to installing in an attic. I would be worried about condensation freezing. All I can suggest is you voice the concern to the contractor and have him explain to you how he will deal with it. I suppose he could use an electric heat strip to keep the condensate drain warm, but again I assume he knows what he is doing.

Before you start the discussion of pricing and equipment quality, you need to make sure the equipment is properly sized. Equipment which is too big can be just as bad and often worse than equipment that is too small. Did this contractor do a load calculation or did he base the sizes on what you currently have? If he did a load calculation did he explain it to you and show you how the sizes were determined? What is the size of the first and second floor? Do you have a walkout basement or is it mostly underground? The quote for the attic doesn't make sense. Are you replacing the current heat pump with a furnace? If it is a furnace then why does it say 17.5w? I don't think you need 5 tons of cooling and 160K BTU of heating. Do you know what sizes you currently have? Did the old equipment keep the house cool in the summer and warm in the winter. Final question, do you have access to natural gas?

Patrick,I did option 1 in several commercial environments,a few residential homes and have pre-filters on my units. I use spun polyester and paper pleat merv 8 pre filters along with merv 11 finals. Those with health issues should consider using merv 13 or higher as the final. Big box store 99 cent fiberglass filters are slightly better than running without a filter. I did some testing several years ago using professional tools monitoring and evaluating air flow,refrigerant pressures,temperature drop/increase across coils and compressor amps/reaction/performance. In the field,pre filters proved to enhance performance,equipment life and operating.maintenance costs. I have written about and reccomended the arrangement a number of times on this forum. Almost without fail,the idea has been met with disagreement claiming it to detrimentally restrict air flow. When dissenters are asked about flow restriction as result of poor quality filtration,they claim annual coil cleaning solve's that. Anyone know how to spell self-serving bias? The increase in final filter life is easily better than five times that where no pre filter is used. It is beneficial to performance and cost savings to install as large a filter rack as room allow's. As for option 2,that is actually how many large homes are set up and to respond to the big scary dust mite story, common sense tell's us different. If and when anything set's up shop inside the return,it will be trapped by a high quility filter and wind up at the landfill next filter change. With that in mind it should be evident that if one chose option 2 then later went to option 1,duct cleaning will not be required. Beating the drum regarding one's own credentials is pretty common on this forum. I am retired and have no reason to participate in self promotion but for what it's worth,I didn't attend the 2 week trade school training but I do have more than a few college credits in mechanical and electrical fields. Let the nay saying begin.