In a quandry...
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)??
Last edited by thtwbstgrl; 08-19-2011 at 09:31 PM.
the power company told you correctly...dual fuel gets my vote
Pricing is not allowed - please delete.
As for dual fuel or electric back up, climate and utility rates will be the deciding factor. There are energy calculators available, or someone here may have some formulas to determine which will best suit your needs.
"Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler
Sorry! I redacted the prices ~ I'll keep searching for a way to find to figure the relative operating costs, i suppose.... if someone has those, yes i would greatly appreciate !!
looking at the hvacopcost site... does "Degree Days" under heating actually mean degree hours (as the cooling side shows)? I actually have the breakdown for our area from our now-irrelevant geothermal quote so i think i can get pretty accurate here ~
Ok not sure if i did this right, but i added up hours per year over 72° as cooling (i know... 72 is not really hot but husband likes it cool), then i added up hours/year from 32°-57° as the "heat pump" heating hours, then <= 32° as the auxiliary heat hours....
It seems like the main comparison i'm concerned with is that less than 32° number, since that is where it will either be all electric or ng with the dual fuel system...
I get $302 operating cost at those temps for NG at the current rate, and $591 for electric at those temps.... Of course if that 17% rate increase they are lobbying for goes through that goes up to 698.
Am i thinking straight on these calculations before i go to husband and tell him we need to spend more on the dual fuel?? Also, any insight into the "it's going to cost a lot more becaues of the defrost cycles" claim from the independent HVAC guy ?
The other concern i have about him is that he was offering to put in a 5 ton system with no changes to increase the duct work capacity. I have read in several places that the duct work capacity should match the capacity of the system so this was a red flag to me, but i am having a hard time convincing husband not to believe everything he's selling since the "independent" guy is trying so hard to save us money!!
Have your husband ask that guy how much electric the resistance heaters will use during defrost, and then how much gas a furnace would use during its shorter defrost time.
If he can't answer that with a better answer then "not as much gas as the furnace will use" answer. Then he has no idea which is cheaper. And is just trying to sell on low price.
I think the second guy's brother works my area.
these were the clues:
hp over ng
zone with multiple units rather that zone dampers
(btw multiple units are multiple units...not zoned system)
change of tune when you asked educated questions
assumption that utiltity guy was nuts
not addressing ductwork modifications or giving a price
(translation..doesn't have a clue)
if ng is what you have, you should be aware that the equipment
cost is more, but it is more efficient.
air from supply registers is much warmer than hp
efficiency costs are always upfront. savings are life of equipment.
cost of ng and electricity are always a determing factor.
best of luck.
The cure of the part should not be attempted without the cure of the whole. ~Plato
On the duckwork sizing. Each zone can handel all the air from the present system. If you "dezone" the combined ductwork should handle more.
But some one that gets an attitude when you are talking about spending a wad of change.....
zones can work well but you are adding more stuff to fail.
multiple systems are more expencive to instal and run, but if one fail you at least have climate control in part of the house.
talk to the neighbors and find out who they like, don't like and why.
I vote for dual fuel. On the off chance that you get a long cold spell in SC your electric meter will spin like a helicopter. BTW why did you decide not to go with Geo? Big upfront costs but HUGE savings.
I vote dualfuel or geo. Geo gives the best bang for the buck and still has a 30% tax credit. Dual has the benifit of adjusting to energy cost change. Heat pumps can run down to 0* but won't be able to maintain indoor temps that low so the back up will need to cycle once the outdoor temp gets below balance point. If electric price go up you can run on gas only, if gas rises you run the pump as much as possible.
As for the contractors, did either do a load calc? If not keep looking. Check refferences, don't be affraid to question everything, especially if it seems off.
As for the zoning, I have zones systems out that are over 10 years old with no problems. The key to this and all HVAC is HAVE IT DONE RIGHT!!!!! Usually if a dealer doesn't have a good reason for an opinion it usually means he has no knowledge in that area and doesn't want to mess with it. If he has done it a couple of times and has bad luck he will tell you why he doesn't like it.
While I am sure you have a budget you want to work with, don't let that be your deciding factor. I suggest you go to www.acca.org/tech and look for a quality HVAC installation check list. It is a form you can download to evaluate the contractors you talk to. I think you may find it useful.
We decided against the geo primarily due to the upfront cost, and while we don't forsee moving, in the event that we do have to move for some unforeseen circumstance, we would not be able to recoup the cost. I really didn't realize how much conventional equipment has improved in efficiency, so once we saw that we decided it would be a good move to go with a much more efficient conventional system.
I believe (though I will confirm with the one we're still interested in, to be certain) that the 2 big companies did load calc. I got a "GeoLink" analysis from the WaterFurnace dealer. We gave them the dimensions of the house and they made measurements of the windows with exposures, etc. when they came out to look at the house. I was not here when the individual guy came out so i'm not sure what exactly he looked at.
I'm going to call the Lennox guy and confirm about the load calc and also how much less it would be if we forego the zones... without that equipment/installation, i have a feeling his price will not be all that much more than the individual guy who is being so difficult with me and trying so hard to convince us that he's the way to go because he's the only one looking out for us.