Our house is a bungalow (a "stepless ranch") comprising about 2,500 square feet. Four bedrooms with two and a half baths. It was built in the late 1970's and the attic-mounted air conditioner is original while the furnace is probably about 20 years old. Both are due for replacement.

The existing air conditioner is a 4.5 ton Rudd unit and the furnace, well.. I don't really even know what brand it is. Nor, I suppose, do I really care :)

I've had 3 guys come in and offer estimates. The first guy was very professional, recommended by a friend who used him to install her furnace. One thing I liked was that he offered a pretty reasonable (I think $140/yr) maintenance schedule to keep everything up to snuff once installed. But he did not do any calculations or measuring besides estimating the needed tonnage of the air conditioning unit based on the power connections and outside coil size and reviewing all the registers and returns throughout the house. He also inspected the current ductwork.

The second guy walked cursorily through the house, indicated a disdain for variable speed furnaces and indicated that he could get pretty much any furnace I wanted for a very good price.

The third guy noted the model number of my existing air conditioning unit and went and looked it up to determine what the existing tonnage was. Then went through the attic to inspect the existing duct work and reviewed all of the registers and returns. He then returned a week later to fully measure all of the rooms and did the calculations to determine the proper a/c and heater sizing should be for the house as well as offering recommendations for additional registers in some of the more poorly served areas of the house.

I discussed a desire to zone the house with each of them, as well as to include a humidifier solution and an allergy-suitable filtering solution.

It seems that to zone the house will require pretty much removing the entire duct system and replacing it.

As my existing furnace is in the attic over the garage, I was warned by at least two of them that a humidifier system up there would need a waiver as there is the potential for freezing and associated pipe bursting issues.

I had initially thought to install some kind of heat pump or heat pump / gas hybrid furnace but it seems that the cost for that would be prohibitive.

Anyway, I received estimates and would really appreciate if folks could give me some opinions on their reasonableness.

This from Coolray:

Trane XV80 (16 Seer) (model numbers unreadable)

Listed scope of work:

Install new Trane (5) Ton XL16I (16) SEER R410A Dual Fuel System to include Heat Pump Condenser, Coil, pad, variable speed furnace, new refrigerant lines, metal plenums, safety pan w/switch, drain sensor, new EWC Electronic(3) zone system, New R8 Supply and return ductwork, new Trane clean effects high efficiency air cleaner and vision pro digital t-stats. Lifetime parts and labor warranty w/annual maintenance.

Steam Humidifier S2000 add $1,295 and will need electrician to add separate circuit.

$11,698 (system)

$ 3,885 (ductwork)

$ 2,915 (zoning)

-$1,000 (federal rebate)

Total $17,528

This from Seasonal Heating & Air:

(They actually provided me with 6 variations, this is the one most in keeping with what I would want)

Heil Equipment:Premier Grade with 5 year no hassle warranty

Duel Fuel system

4 ton 13 seer heat pump R- 410 A freon

4 ton 13 seer coil

80% gas 100,000 BTU furnace

Remove existing furnace,existing coil,all ductwork and discard

Install all new duct work R-6 Flex

Supply Plenums, Return Plenum

Add 3 supply outlets( master closet, work out room, laundry room)

1 year labor warranty

compressor 10 year warranty

parts 10 year warranty

limited lifetime warranty on heat exchanger

Optional items:

Programmable t-stat(s) 7 day = 100.00

Touch screen thermostat = 300.00

Humidifier(s) = 450.00

Media air Filter(s) system= 300.00

Electronic Air cleaner April Air 5000 = 950.00

Total (w/o optional items) $6,000

This from Bardi Heating & Air Conditioning:

Install New 14Seer 5 Ton R410-A Variable Speed Heating and Cooling System

The above price includes all equipment, labor, and materials to install a new American Standard 5 ton Heating

and cooling system in the attic. Add supply to master closet and hallway. Add supply to laundry and create return

from existing supply in laundry at door. Install 11/8 x 38 refrigerant line set down exterior to new unit location.

The warranty is 5Year Parts, 10 year compressor & 1 Year Labor.

Equipment is (American standard):

AUD120R9V5 variable speed 2 stage gas furnaces

4TXCC060 Aluminum Evaporator Coil With TXV

Total $15,165

So, what do you think?

Here is a link that might be useful: More comprehensive blog post on my Furnace A/C replacement