Hello Your heat pump air-to-air sounds like the best options. If you dont need to use it for water the COP is quite high, usually COP-3-4. The COP means a ratio of what you get out vs what you put in. The COP of 3 is 3 times the heaat of what you put in. There are a number, some that get a COP of around 5 using source of 30F. Others list between 3-4 quite generally. Carrier is a maker of one type which has a COP of 3 and is a small size. When the source (outdoor temp) is low the COP goes down as does the output. (Below freezing especially). Its worth having an oil or wood or gas heater to go with the system as back up. Heat pumps that can heat water have to work harder as the water is warmer than the air used in buildings, so they use expensive CO2 heat pumps which will set you back about $5K easily. Therefore I would suggest keeping a boiler system, outdoor boiler. An indoor stove needs fresh air which is not ideal for heat pump system which works ideally with heat recovery on the ventilation system (extract heat from waste air at 90% or so efficiency). A neat approach may be to operate an air -to-air heat pump, aim for as high a COP as possible, but install a gas boiler if you have this. The smaller boilers, condensing systems, are surprisingly cheap. If you install a waste water heat recovery system which is just aa heat exchanger on you waste water from your shower, you can half the energy you need and thereby get by with a smaller boiler and consume only about 4-5kWh/day for shower water. A condensing boiler works most efficiently when working with water heating rather than central heating, and plus, the typical condensing system now heats so quickly that you dont need a hot water tank, reducing loses. You would still have at least 15KW available for heating the home. This can be done by putting in a heating loop into the air ducting that is shared with the air-pump. This could be a compact fan assisted system. There would be expense in heating controls for all the ducting. However, if you cannot put in ducting, then you can install a water radiator central heating system. To work with a heat pump, you can go for the super-efficient CO2 based systems that are emerging but expensive. The efficiency can be raised if the heat is needed at a low temperature, so requiring either under-floor heating or a 'fan assisted radiator' which extract more heat and can return the water to the heat pump much cooler than normal radiators, and require a lower temperature, raising COP. I would go with: Waste water heat exchanger ( I guess $500 est with capital cost $200-$300 plus basic installation if incorporated with a boiler installation and pipework anyway) -this will reduce the energy requirement of the condensing boiler, potentially allowing a smaller system. Condensing boiler - 15-25kW output, 90% efficient, capital cost $500 ebay Air-to-Air heat pump (in loft) - COP 3-5 (later figure seen in an Austrian GSHP but should work with airsource unless outside air is usually very cold?) cost? controls? Fan assisted radiator in ducting for backup (run off boiler)? Ventilation heat recovery

Thanks for the feedback everyone. I've decided to go with the Carrier Infinity system. It seems like a nice product and I like the contractor (and they are required to follow SCE guidelines). I did ask him again about a Carrier coil, but it wasn't an option. That might be the case, or it might be a cost issue, but he isn't going to budge. HVAC Calc actually suggested raising the outdoor summer temp by 5 for the safety factor. I doubt if they'll be able to do that for me on Manual J though. HVAC Calc was useful since I had the chance to play around with some of the settings. Going from r6 to r8 ducts makes a big difference as suggested. It's much easier and probably less expensive than going from R30 insulation to R38. This contractor also mentioned that he uses R8 normally. Thanks again everyone.

To add some more info, all were asked regarding Trane XV95 and XR15 The first bid quoted. XV95 TUH2B080 XR15 2 ton 4TTR5024 Second bid proposed XV95 TUH2B080A9V3 And XR15 2.5 ton 4TTR5030 This bid also specified evaporate coil 4TXCB031 The third bid quoted XV95 and, I think misunderstood me and quoted XL15i 3 ton with no further specification. I can always tweak the specifications, I guess and boost one unit up or down, or clarify with the one company that I am interested in XR15 and not XL. But what is what is concerning me is the issue of the size differences. The first and second salesmen did come in and asked some specifics. They looked at windows and doors and measured off the entire interior of all rooms. I believe they noted the fireplace and skylights, as well. One inputted it all in a software program and came up with the 2.0 - 2.5. The second guy took notes and went back to his office. A few hours later he sent me a very clear email with all info easy to read etc. For all I know, he may have done computer calculations back at the office The third guy just came in, looked at the existing equipment and duct work, the chimney, as the others did also, and sat down and wrote the proposal. To be honest, unlike the others, I don't even recall him measuring the furnace, closet or existing sheet metal. Lastly, briefly, what constitutes a proper load test and how best for me to get that. It seems that even the more established and certified Trane dealers around here may not be providing them. Thanks for all the input.

ACCA Manual D, requires 'that' sizing of the filter area for the cheap fiber-glass throw-away filters; also a good way to go for most other filter's except the real deep pleated filters. They will tell you that is not important; but it can make a big difference in airflow & better filtration. Search: Hart & Cooley engineering Design for sizing Return Air filters; on their charts (Ak) means sq.ft., of Free-Air-Area... A filter-rack is like a return air filter in the ceiling with a grille over it; or two separate ductwork filtered drops to the Return Air blower chamber. It is good efficiency design for anything requiring above 800-CFM of airflow, or anything above a 2-Ton A/C. There are also a number of ways a good tech can check the "Delivered Performance" of an A/C or Heat Pump; this should always be done; otherwise you don't know what performance you have, or the level of performance you paid for & didn't get! Far too many don't know how to do it any of those performance checks; it's the only way you know what your getting.... I can even tell you various ways you can check your A/Cs performance just using a low cost indoor humidity gauge & a good low cost 'preferably' digital thermometer. Here is a link that might be useful: Checking duct airflow and equipment performance