It's New Gas Furnace Time! Your experience appreciated.

1,900 sq ft split level CBS ranch, circa 1964, with a flaky natural gas furnace.

Time to replace it. Currently, have a Lennox Conservator III G16, Model: G1603/4-100-3, Input: 100,000 BTU/Hr, Air rise: 35-65 F, and ducting to match. Only have 5,000 sq ft of lot, and drilling is not practical, so practicality of a ground source heat pump doesn't seem to be there.

BTW, the available cost data right now from the first dealer's bid shows recovery of the higher furnace cost won't be possible within fifteen years, by which time we will likely be out of this house.

The optimum solution seems to be a 90% furnace, as over ten years it looks less expensive than the 80% also proposed. Data, transposed from a spreadsheet, follows.

If you have recently replaced your furnace, would appreciate hearing how you did it and what you learned. The comment link (in green at the end of this item below) is open! Thank you kindly in advance for your on-topic remarks. Sales droids will be spaced, out the airlock, ga-WOOSH!



Dealer estimate
Gross price
Oregon & NW Natural rebate
net up front cost
finance cost
total furnace cost
est yearly fuel cost
5 year cost
10 year cost
15 year cost
(All figures in current dollars)

Dealer estimate for REPAIR
Gross price = $1,560
state rebate = $0
net up front cost = $1,560
finance cost = $0
total furnace cost = $1,560
est yearly fuel cost = $840
5 year cost = $7,320 (assumes re-repair every 5 yr., same cost)
10 year cost = $13,080
15 year cost = $18,840

Dealer estimate for REPLACE W/ 80% EFFICIENT FURNACE
Gross price = $ 2,600
state rebate = $0
net up front cost = $2,600
finance cost = $7 on balance we can't pay for immediately
total furnace cost = $2,607
est yearly fuel cost = $735
5 year cost = $6,282
10 year cost = $9,950
15 year cost = $13,625

Dealer estimate for REPLACE W/ 90% EFFICIENT FURNACE
Gross price = $3,400
state rebate = $200
net up front cost = $3,200
finance cost = $49
total furnace cost = $3,249
est yearly fuel cost = $653
5 year cost = $6,516
10 year cost = $9,733
15 year cost = $13,000

Dealer estimate for REPLACE W/ 94% EFFICIENT FURNACE
Gross price = $4,700
state rebate = $550
net up front cost = $4,150
finance cost = $116
total furnace cost = $4,266
est yearly fuel cost = $626
5 year cost = $7,393
10 year cost = $10,405
15 year cost = $13,533