Thanks for the replies tigerdunes. • The insulation is average to good. There is about seven inches of fiberglass batt in the attic and all obvious thermal chimneys have been insulated (i.e.insulation over lighting cans, etc). We have insulation in the walls, but it would be that typical to 1960s and fair at best. We are considering adding another twelve inches of fiberglass batt to the attic but must address certain existing storage complexities. • Of the finished basement, 800sf is below grade and 400sf is at grade (400sf dedicated to a lower level garage is at grade but not included in the figures). • Electric (NStar) is $0.162/KWh unit cost (delivery and generation costs; fixed costs not included). Gas (National Grid) is $1.3463/Therm unit cost (transmission, distribution and supply costs; fixed costs not included). • The current furnace is and new furnace will be located next to the internal chimney in the front-center of the house, primarily because of front-center existing duct work but also for space considerations. • The venting of a high efficiency condensing unit would be somewhat problematic and aesthetically unappealing. If we went with a high efficiency furnace, then we would also like to install a high efficiency gas hot water heater, because it seems counterproductive to install a smaller flue liner for the existing gas fired hot water heater. Due to setback requirements and snow requirements, there may be a very tight area in proximity to the furnace where two exhausts and one intake could be installed; that area is close to the front door and would be unappealing to my wife and would require some additional carpentry work. I don't believe we have a straight shot up the existing flue because of the main floor fireplace, but I have yet to check. • We are unsure whether or not the existing furnace is short-cycling (i.e. shutting itself down for protection reasons). The cycles are certainly short, but I would guess not, only because we do reach thermostat set temperatures, although it wouldn't be a big surprise. • We have not received the Manual J; we have only been told the results from a whole house standpoint. We are requiring the receipt of the load calculations prior to installation but after a vendor has been picked. • The ductwork has been examined by the dealers. We have one large single return for the main level living zone, one large single return for the lower level zone, and a small return in each bedroom in the main level bedrooms zone; the returns are coupled as a common return prior to the furnace. The zoning, ductwork and returns are very good for the 1960s, but uninsulated and based on five inch supplies; so, the system would be undersized for today, I believe. All ducts are internal to the house, although some run through the garage; all ducts are enclosed and finished, other than those in proximity to the furnace. No modifications will be performed to the ductwork, other than any transition needed to the new furnace. • There is seven inches of fiberglass batt between the eight inch ceiling joists (R20). • The zoning control board will control the HVAC system. The new thermostats are dumb, although nicely programable and aesthetic (Aube/Honeywell TH141). In addition to a common (C), the thermostats accept 24V (Rh), heating (W), 24V (Rc), cooling (Y), and fan (G). The new thermostats do not have any second stage inputs or reversing valve input; we have five wires at our existing thermostats; the new thermostats can be battery powered. • The dealers are familiar with zoning, and with either a dumb-simple zoning control board for heating and air conditioning or a smart acculink system; they are less familiar with the combination of smart zoning control board and dumb thermostats or a dumb-sophisticated zoning control board and dumb thermostats. I am personally unimpressed with the smart thermostat systems; to much unnecessary/unused information; to expensive; to large and prominent. What are your thoughts? • The job is simple, although the air conditioning installation would be new but typical. It seems that I should have about $2500-$3000 in air condition installation cost and about $2500 in furnace installation cost and about $1000 in miscellaneous cost (including the $150 zone control board and the media filter), for $1600 in air conditioning equipment cost (2.5 Ton, 15 SEER) and $1800 in furnace cost (80K Btu, 80 AFUE). That would be $6000 to $6500 total cost. What is your experience for pricing of such a system?

Solution to this problem. When you update your system from single stage to 2 stage, you must have C wire from outside unit. My old single stage system came with 3 wires from outside unit to indoor (blower) and Indoor unit to thermostat had 5 wires. I solve this problem with new wiring the whole house. I install 4 wires from outside unit to indoor (blower) (red(Rh), blue(C), yellow(Y1), purple (Y2) (mine had a purple)); Indoor unit to thermostat install 7 wires, which following below. red (Rh) blue (C) yellow Y1 Cooling stage-1 Gray Y2 (Purple Y2) Cooling stage-2 Green (Fan) white (W1) Heating stage-1 brown (w2) Heating stage-2 If you don't want to rewire, I recommend to get CTK04 thermostat, which will be fine with your old wiring.

Set the thermostat so it is not calling for heat. Then measure the voltage between the C terminal and the G, W, and Y terminals receptively. The G terminal controls the fan independently. In most furnaces the fan will also turn on if the Y terminal is energized. All of these terminals should have zero volts. If they are then it is a board problem and not the thermostat. If it is a board problem then the relay that turns on the blower motor is either stuck closed, or a connection problem on the board is causing it to close and never open. The blinking lights are unlikely to indicate if there is a connection issue or a stuck relay. Did something happen to this board that caused the connector pins to bend and wires to break? If you are up to replacing it, you can buy a new board for $90 and have it shipped to your house by the next day. If this board has had physical damage, then I suggest replacement is the best long term solution.

I would start by Check for voltage on the control board. If that checks out start tracing the low voltage wiring at the contactor. Sounds like there may be break in the line somewhere.