Dual fuel heat pump- right decision?
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/yr for 13SEER 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?