Dual fuel heat pump-right decision?

[golfinator]

We’re in Atlanta in a 45 yr old, 2650 sf tri-level brick home. The 2 of us are close to 70 and not sure how long we’ll be in this house, but probably about 5-10 yrs, maybe less. Existing split system- 4 ton Lennox Mod 10AC48 (18 yr old) that’s developed a leak + Singer furnace (26 yrs old) . Have quotes to replace A/C and furnace. Most of the salesmen didn’t propose dual-fuel heat pump, until I mentioned it. Wondering if it’s a good idea, due to extra cost ($400-600 DFHP + $800-900 var. spd furnace) and also comfort- not having hot air immediately?
My gas usage aver. 900 therms/yr @ $1.24/therm. Heating months (Nov thru Feb) aver.163 therms/mo @ $1.04/therm. (we have a gas dryer, cooktop, new water heater.) Gas provider showing $333 savings/yrfor13 SEER DFHP w/80% efficiency furnace over 13SEER AC w/80% based on $0.80/therm.(not including other mo. add-on charges). My new rate is $0.67/therm.+charges). Electric aver.15,000 kw/yr @ $0.13/kw. During the cooling months (May thru Sept) aver 1800 kw/mo.
Furnace & coil are on slab in crawlspace. Plastic covering the crawlspace dirt and, with a 25 pint dehumidifier running most of the time, aver 55% humidity and 70-75 degrees.
Also, should rigid ducts in crawlspace be cleaned, resealed, reinsulated vs replaced with flex ducts?

[HayZee518]

you won't buy efficiency from flexi ducts. the insides are yellow fiberglass and will retain dust and moisture. sheet metal ducts, covered with insulation is the way to go.

[dfitz3390]

you won't buy efficiency from flexi ducts. the insides are yellow fiberglass and will retain dust and moisture. sheet metal ducts, covered with insulation is the way to go.

not necessarily the flex ducts i have are lined so that wont happed

[paul52446m]

We’re in Atlanta in a 45 yr old, 2650 sf tri-level brick home. The 2 of us are close to 70 and not sure how long we’ll be in this house, but probably about 5-10 yrs, maybe less. Existing split system- 4 ton Lennox Mod 10AC48 (18 yr old) that’s developed a leak + Singer furnace (26 yrs old) . Have quotes to replace A/C and furnace. Most of the salesmen didn’t propose dual-fuel heat pump, until I mentioned it. Wondering if it’s a good idea, due to extra cost ($400-600 DFHP + $800-900 var. spd furnace) and also comfort- not having hot air immediately?
My gas usage aver. 900 therms/yr @ $1.24/therm. Heating months (Nov thru Feb) aver.163 therms/mo @ $1.04/therm. (we have a gas dryer, cooktop, new water heater.) Gas provider showing $333 savings/yrfor13 SEER DFHP w/80% efficiency furnace over 13SEER AC w/80% based on $0.80/therm.(not including other mo. add-on charges). My new rate is $0.67/therm.+charges). Electric aver.15,000 kw/yr @ $0.13/kw. During the cooling months (May thru Sept) aver 1800 kw/mo.
Furnace & coil are on slab in crawlspace. Plastic covering the crawlspace dirt and, with a 25 pint dehumidifier running most of the time, aver 55% humidity and 70-75 degrees.
Also, should rigid ducts in crawlspace be cleaned, resealed, reinsulated vs replaced with flex ducts?

For just 8 to10 yr.s i would just put new furnace with air. Insulate outside walls of crawlspace and just clean ducts but not insulate ducts. I don't like flex duct in a crawl because most co. don't hang it good enough, so it restricts air flow. Flex duct done right works fine . Paul

[LarryHome]

Homes with dual fuel heat pumps generally get better efficiency in terms of price and usage in longer periods of use, so I think you would be better off replacing it with a newer Lennox model like the one you wish to replace.