Hello HVAC folks! I find myself going nearly crazy over making decisions regarding our HVAC We are in a 17 year old house with (?? age) single stage 10 seer AC unit and a 17 year old furnace. There is currently a zone system that is malfunctioning or not functioning at all. We decided a month or so to go ahead and get the equipment replaced and the ductwork fixed so our house will be comfortable again and hopefully a lot more economical to heat & cool. Here is the dilemma. We have had 3 quotes on work. The first quote was actually for geothermal with a comparison quote for a high efficiency system. We decided against this contractor. We are down to 2 choices. One is a large HVAC company. One is an individual HVAC guy. Here are the two systems:
Big HVAC company bid:
Dave Lennox Signature Collection 4-Ton 16 SEER Heat Pump (XP16) Dual-Fuel System with 80% Eff. Signature Collection Furnace (I think SL280V). Correcting the ductwork and installing a 2 zone system with matched Lennox zone system. Price after rebates and tax credits: (price redacted)
HVAC Guy enters the picture telling us that we do not need zones and they never work properly, break too much etc. He recommends taking out the zones entirely and just setting the house up with sealing up the ductwork and correcting it if there are any problem areas. He will install 4-Ton Whirlpool Gold 16 SEER Multi-stage Heat Pump (no dual fuel) with variable speed (WGHP46 16 SEER) with variable speed fan air handler. (price redacted) + as yet unknown cost of materials for duct work as needed. (36% lower than big HVAC company quote)
Here's where it gets kindof weird. I had the power company come out and do a mini energy audit as part of this effort. That guy said immediately upon me telling him we are replacing the HVAC that we should go with a dual fuel system because when the outside air temperature drops below 32° the heat pump will kick into aux heat and will run the electricity up like crazy. Makes sense to me.
With this in mind, I call back HVAC guy who basically responds as if this guy is nothing short of crazy and should probably be fired by the power company for suggesting this and what's more, I am just confused from doing too much research. He insists that in our climate (Upstate SC), it makes no sense to get a dual fuel system and goes on to say that the dual fuel unit will use way more natural gas than they are telling me due to the defrost cycle. He also offers that he now thinks, that if we are really committed to zones in the house he would recommend doing 2 2-ton units and he'll get back to us about what the difference in cost would be for that. I doubt he will give me the dual fuel quote i was actually calling to ask for.
But basically, this last exchange has left me wondering about this guy. Is there a scenario dual fuel doesn't make sense? Does this defrost cycle element really make them less efficient? Mostly I have begun to feel like the individual HVAC guy is like "don't you worry about it, I know better than you and this is hogwash." I guess I'm just confused as to whether to believe him or not. And while I feel like the power company guy, who has no vested interest in me saving money on my power bill by installing a dual fuel system, seems like a non-biased resource in this context, how can I know.
Are there any resources out there to see the relative operating costs of these two *seemingly* similar heat pumps running with either electric backup or NG backup (dual fuel)??