Thank you for your response Tigerdunes. I will definitely check with the bidder on the third party evaporator coil. I specified matched systems having read your prior posts to others extensively, but didn't catch that this evaporator coil wasn't a matching Trane. Thanks. The boiler was sufficient in heating the entire 1200 square feet main floor living space with AND without all the radiators in place. I don't recall the size at the moment, but will check. The HVAC people were all pleased with its size when they looked at it. Because the house is without electric and water service as yet, we are not totally sure the boiler is still in working order. It was not fire damaged, but water from the fire fighters and heat from the fire might have caused some unknown problems, which was another reason to hedge the bet by adding a gas furnace. The second reason for considering a gas furnace, not just A/C is that a realtor who knows the house and its value, - which is considerable for a small house, given its location and craftsman, cedar shingled cottage charm - suggests that some buyers don't like radiator systems, and feels the addition of an alternate heat system and the addition of A/C will be worth it, which is another reason I got the bid for it. The third reason for considering a gas furnace is code compliance, and the cost to do so. The cost of adding hydronic units to the sunroom, pantry, dining room and bath areas to meet code are unnecessary if I install the gas furnace. Anyone wanting to use the radiator system only for heat would have to add these units, or live without them as I did, but code is met with the addition of a furnace. No furnace, and I have to add radiators in the areas mentioned above and detailed below. I agree that a heat pump would be the way to go if we knew for sure that the radiator system was going to be the primary source of heat as it was when I lived in the house. New owners might opt for a forced air system. My question on this is, can a gas furnace be added into the system as cost effectively later as it can be added now with the A/C going in. The new heating system, if installed, l would heat/coo the 1200 sq ft main floor with its 9 ft ceilings, with two registers in the open 950 sq ft unfinished basement. The basement stays cool in summer and warm in winter without additional heating and cooling. The attic space, if developed later, will be heated and cooled with an in-wall, Mitsubishi type system. Trying to run ducts and vents is a problem, which is why we don't have the new proposed system sited in the attic. It would make the attic fairly unusable in a future development as a master suite and sitting room. The ducting layout using the in the basement location has worked well, and the location of cold air returns well placed and spaced. So the attic will not be heated or cooled with this system. In the past, with the boiler, the heat loss from the main floor was enough to keep the attic above freezing, but does not warm it significantly. The attic has 4 large double window sets, 3 large Velux skylights and a 4.0 french door set, and the roof is black, so it stays warm enough on sunny days, and is well ventilated in summer.. The attic floor will be re-insulated at this time, but not the walls or ceiling. The new insulation in the attic floor will be far better than the old, and as I said, the new windows throughout, from basement to attic are a vast improvement in energy efficiency over what the boiler used to have to handle. The 950 sq ft basement is unheated at present, though I believe two registers will be added to this space with the new furnace The basement stays comfortable in winter when the boiler is in operation simply from the hot water pipes to the radiators and hot water heater and warmth of the up stairs. It is is open space, unfinished and only used for laundry and workshop space/tool storage. The dining room radiator was removed from under a south facing bump out window. That window was removed and replaced by an exterior double french door when a new deck was added at the time of the new boiler. The heat loss to this room was noticeable but not enough to be a problem for me, though it would be for others, and it is for code. Each room has to have a heat source, so I either have to put in a register or add a radiator. The bathroom is only 6x7 and is now warmed by the heat/fan which is not sufficient for code. I have a not yet installed hydronic towel bar that gives off 1500 BTU, enough to handle the bath and the small hall adjoining the dining room, bath, bedroom and parlor. If I do the gas furnace, this is unnecessary. At same time the new boiler was installed, a kitchen was installed in a 11x12 ft space that only had a sink and refrigerator with a radiator. An adjoining but separate 6x8 pantry at the south end of the kitchen had a stove and a cabinet. The pantry is also an access corridor to the basement stairs. So in installing a kitchen, I removed the radiator and replaced it with a toe kick radiator under the sink base the fully fitted kitchen. Base and upper cabinets were added to the pantry on the load bearing exterior wall that separated the pantry from the screen 8x8 screened back porch at the other half of the kitchen south wall. The fire that started at the electric service connection into the house was located on the east wall between the kitchen and screen porch, so this area and the attic above it were severely impacted by the fire. In rebuilding this area, the screen porch got a solid foundation, was mostly opened to the kitchen, and serves as a sunroom breakfast area. It is,fully windowed from ceiling to 36 inches above the floor with a door that opens to the deck. The load bearing wall separating the sunroom from the pantry still exists, but the pantry is now open to the kitchen rather than walled off with a doorway. The kitchen toe kick puts out 5,600 BTU and has to handle the kitchen sunroom and pantry area now. If I do not add a furnace, code will require me to heat the sunroom and pantry areas, which I would do with toe kick units under the pantry base cabinets - one venting into the sunroom through the wall and one venting into the pantry. If I add a furnace, this will not be required, we will simply use those areas for the forced air registers. If I do not add a furnace I will have to provide hydronic heat sources for both areas. So, to answer your question 4, the only addition to the heat load that the boiler has covered adequately (1200 sp ft) is the 8x8 fully weatherized and insulated sunroom. If I go with a gas furnace we will add the register(s) for the unfinished basement. I don't know if code requires the basement to be covered. I do know the non living space attic does not need to be covered. Sorry for all the detail, but I find that sooner or later the information is needed, so I am trying to give it all upfront.

If both furnaces are installed in the basement, more rigid duct work would have to be installed, but the lineset and the wiring would shorter. I don't think there would be much difference in materials. There would be more labor. It takes more work to run the duct work up from the basement versus running flexible ducts in the attic. I have no way of estimating this. I would think an extra 2-3 days of labor should do it, but I could be way off. The plans would have to modified. You second quote for the HVAC equipment is $21,850, not $26,000. I like the second quote with the 2-stage furnaces. Remember this quote is for over sized furnaces and condensers. I don't understand why there is a separate quote for gas lines. Is this considered an option? I am not convinced you need a humidifier. You can always get a stand alone dehumidifier later if you need it. The kitchen hood is good if you like to cook.

@tigerdunes & mike_home: Contractor 3 & 4 I have felt good about. Contractor 3 initially added small amount of R22 free initially. He must have gotten very busy/ or tired of my questions as his responses have slowed down to grind. Finally heard back form Contractor 3. He stated "supply plenum is large enough, they can re-build return plenum for $225. He is using a slab coil because airflow would be better, Supply plenum for A-COIL would be smaller" He said supply plenum is big enough w/o rebuilding. I requested he price out Option 1 with Carrier Infiniti with the 58CV(A,X)090-16 furnace instead. He stated "Again furnace was chosen for airflow. 58CV(A,X)090-16 IS ONLY 17” WIDE instead of 21”, Smaller plenum". Did not re-price. Contractor 3 said keep in mind Perfect Fit filters cost 3X of Aprilaire. Final Prices incl similar duct work repairs w/ utility rebate, instant Trane rebate for T-stat. Contractor 3: $11,267 total. Can't fit me in on schedule til 1st week of May. 3-4: Trane XR17 (16.0/13.0): 4TTR7048A1, UD2C080G9V4, 4TXFH054CC3, XL824 Scope: Rebuild return plenum and keep supply plenums (slab coil), R-8, 2” of insulation, auxiliary drain pan, condenser pad, float switches, programmable thermostat, adapt to copper lines, gas connections, seal duct where needed, adapt to vent pipe, electrical, correct size circuit breaker, mechanical permit and inspection, labor, supplies. - Install Perfect Fit media filter. - Replace damaged ducts above second floor (5) & utility (1) and seal flex duct connections - Add supply grille in upstairs office or hall where possible. - Add return grille (12 X 12) in hall ceiling. - Increase duct size feeding kitchen/nook area and 4ft duct board trunk line for better airflow - Replace supply register (15) with wide vane grilles, weather-strip and seal register boots from inside. Contractor 4: $11,463 total. 4-2 XR17 (17.0, 13.5): 4TTR7048A1, UD2C080G9V4 4PXCCU60AC3HAA, XL 824 Scope: Build new supply and return plenums w/ 1 1/2" Owens corning fiberglass duct board (A coil). Add new drain pan, electrical disconnect @ outdoor unit, electrical whip, copper fittings, PVC drain line fittings, gas flex/ gas fittings, exhaust vent, slab as needed per unit specs and city code requirements. - Install Perfect Fit media filter - Transition trunk/branch lines feeding master bed room side and upstairs to new plenum, remove any hard 90 degree turns to provide better air flow to upstairs areas. - Install damper collars on all three flex lines @ front of plenum to provide a means to adjust air flow - Increase sizing of flex (8" to 10") to supply kitchen and nook, remove the distribution box and "Y" off 7" to nook and 8" to kitchen register to provide better air flow to these areas. - Replace all owl flex that is broken open @ upstairs attic (5 drops) & utility (1 drop) with R-6 metallic coated flex ducting. - Cut in new 12"x12" return filter holder grill at upstairs hallway w/ 10" flex to return box @ unit. - Seal all duct work with UL listed metallic tape and mastic to prevent air leakage. - Replace supply register (15) with wide vane grilles, weather-strip and seal register boots from inside.

" I don't consider zoning a choice as 99% of installers haven't got a clue how to do them properly." I agree that the majority of installers won't have a clue, but that's not a reason to dismiss zoning. The design function (and the required competencies) is a separate, albeit related activity to installation. The problem with HVAC systems is that too many installers and service techs think they're competent designers when they don't have a clue. "I am not sure if my hvac engineer is getting it wrong or me, but they seem to be proposing return air vents in ceiling of first floor (and supply registers in floor of the first floor) and that's limiting them." In a predominately heating climate zone it would be preferred to have HVAC returns as low-wall returns. In a predominately cooling climate zone, it would be preferable to have HVAC returns as high-wall returns. There is no reason why both supply and return ducts can't be located in a crawl space. If the crawl space is conditioned (and it should be) then it is a suitable environment for the air handler as well.