I would go dual-fuel for sure. Heat pumps shouldn't cost a fortune more than a regular centeral A/C.

Your climate probably only needs a gas gurnace for a couple months. You could probably get by with just heatpumps. But if you already have natural gas it makes sense to keep the gas-furnace.

I would most certainly take advantage of the tax credit. You can do so either with a 95% gas furnace or a heatpump that qualifies.

I"m not sure if you really want a 2-stage heatpump or not. I heard they are great for humidity control in hot/humid climates. I'm sure you can hit the efficiency status for the credit with the 14 seer model heat pump with a variable speed furnace.

Hope this helps.

speedlever

I would install an 80% eff two stg VS furnace paired with a qualifying HP condenser.

IMO

Initial prices for a dual fuel setup are about $1000 higher than just a furnace and condenser.

That seems a bit high at first glance. I'll see what my other contractors propose.

I'm also getting some pushback on putting a 95% furnace in the attic due to the possibility of water damage. I would really like to use the increased efficiency of the 90+ units if possible, but not if it's not smart due to that risk.

My existing 80% furnace still runs fine... but who knows how much longer? Could be years.. could be months. So the only advantage of putting another 80% unit in would be just to have a newer unit at some less cost due to the tax credit.

$1000 for dual fuel is about what I paid - in Raleigh on a bigger system (and new construction). It was a 90% furnace. Just to throw some numbers out there. This winter - obviously colder than avaerage - I paid about $200 in NG. The house is new and tight so that changes things but 4000 sq feet and lots of windows. Who knows what I paid in electricity for heat. I'd guess it was $500 max. I never had a bill over $200 and my April bill was $95 so I would say it couldn't have been more than $100 a month.

So my heating cost (and yours might be identical) was $700 with a Seer 15 HP and 90% NG - dual fuel. I'd suspect it would be $900 or so with straight NG. That is based on energy audit predictions. So if your numbers are comparable, the dual fuel will pay for itself in 5 years. I'd assume you have similar NG and electric rates.

The incremental savings with a 95% furnace vs a 80% furnace in a dual fuel setting is about $30 a year (for a new 4000 sqft house).

I think my point is don't do dual fuel and 95% furnace. I'd just do dual fuel if I read your situation right. That furnace won't work very much. I'm not entirely sure that you can retrofit your old furnace to dual fuel - it is a stat thing so I'd think it could be done but what do I know?

Yes, the old furnace can be used with dual-fuel controls. Since you will continue to use gas for the forseeable future, the 95% unit sounds good to me. Chance of leak is the same as for the AC function. Heat pump with gas backup in your area will require some gas usage for 4 months, 2 of them light demand. Piedmont Natural Gas charges $10 per month minimum plus usage. Disconnecting for the warmer months is not a savings due to the high reconnect fee. And perhaps you have gas water heating.

busdriver - how do you possibly justify a 95% furnace when it is barely used?

Yes the $10 a month for me is 1/3 of my annual bill. We have gas fireplaces and gas cooktop. My summer bill is $12. Since the wife demands gas for cooking, there was no option. I bet in our climate, that $120 a year pays for itself unless you have a ground source heat pump.

a 95% eff furnace used in a dual fuel application is overkill for Greensboro,NC.

IMO

No Nat gas available at my house. I have propane 92% as backup in the dual fuel system, so the higher efficiency may be justified due to the cost of propane. I also have a non-electric propane vented-exhaust heater in the basement as power-out backup.
Your old furnace probably has standing pilot. A new one with igniter might save about $5.00 per month for the months the pilot is burning.

With regard to the best furnace selection, I have seen multiple references to a proposal that might be included in the Climate Bill. It would be a requirement that any existing housing that is offered for sale must be upfitted to current energy usage standards and approved by the EPA before the sale could occur. I feel certain that some in government would back this proposal. And neither we nor our elected representatives get to vote on such regulations.

bus_driver - I respectfully disagree. There is no way the EPA could check houses before sales - that is absurd. Bringing older houses up to current standards is also a bit draconian. While there are some in government that would back this, most will be gone come November.

Government regs can be really really stupid, but worrying about this is a bit too much. There have been proposals to remove the tax deduction for mortgage interest on houses greater than 3000 sq feet in size - all one has to do is look at the size of the houses that 535 members of congress live in to see that this won't ever happen.

Never say Never ;-)

Here is a link that might be useful: (ECAD) Ordinance for Single-Family Homes

I'm a bit confused. According to wunderground.com, we have about 3500 heating degree days and about 1500 cooling degree days in the Greensboro area. Would that not indicate greater savings to be had in the heating area than in cooling? IE, spend more on heating than on cooling equipment?

I don't need to replace the upstairs furnace. But with the entire system being 17 years old... and considering current tax credits, various utility rebates and mfg rebates, it seems to make economic sense to replace it at reduced cost. I can put in a new upstairs HVAC system and move to a dual fuel (HP with 95% gas furnace backup) for less than $300 difference over a standard split system with 95% gas furnace and a/c.

My wife is concerned about how HP heat feels... since it has had a reputation of being cold heat. But I hear HPs have been markedly improved. And I understand that a HP will be more efficient down to a certain outdoor temp than just using gas alone. Is that accurate?

Reviewing my gas usage, we have about 4 months of significant gas usage (Dec, Jan, Feb, Mar) and 2 months elevated (Nov and Apr).

Looking back over my electric bills, my heaviest usage is June, July, August, and September with elevated usage in May and October.

So it really seems about 50/50 on the heating and cooling requirements.

Yes, we do have gas water heat and a gas range, but have an electric dryer.

The output air from a heat pump is not so warm as from a fuel furnace. In my case, the backup furnace has about the same BTU/hr as the heat pump so the air has about the same temperature. But the personal adjustment to these conditions is rapid. The heat pump can operate with a thermostat differential of 1 or 2 deg. Fuel furnaces may require 4 tor 5 deg differential. Now I prefer the more-even temperature to the old system of periodic hot blasts from a vastly-oversized furnace followed by cooling of 3 or 4 deg before the next heat cycle.

speedlever

furnace would be placed in attic? correct?

while you live in a climate with moderate winters, generally you do not install high eff condensing furnaces in an attic due to possible freezing issues.

what size outside condenser are you looking at?

my suggestion would be the XV80 furnace paired with XR15 heat pump.

or if you have capacity in your breaker panel, a high eff heat pump with VS air handler and backup electric strip- probably a 7.5KW.

you do want a system that qualifies for tax credit.

IMO

Speedlever - you are right that heat is where the money is relative to a/c. $300 makes your decision a no-brainer - you might save that in the first year. It is just that our costs compared to the NE are so low as to not justify a 95% furnace in a dual fuel setup. I remember a 1200 sq foot apartment in Buffalo that costs $450 a month to heat - that would cost $100 or less down here.

But your options are not the 2 best (expect they may be given what happens when government muddles with incentives).

Your best (most cost effective, environmentally friendly option) is a 80% gas furnace and a heat pump (seer 15 or better). You can throw a 95% furnace as backup but the cost is probably $1500 to save $30 a year (and that is a really high guess - it might be $10) - so 50 year payback on something that doesn't last that long. Now if the federal government is paying for $1200 of tat $1500, then that changes the equation a bit. But - it would still be a 10 year payback and a waste of government money.

The 95% vs 80% issue is totally different than the straight furnace a/c vs heat pumps. The heat pumps will save you money - no question.

I would make the argument that your wife will never notice the cooler temps if you have a well designed system. The main problem with this is at cold outside temps and that is when the back up furnace will run.

All this heat pump stuff really pays off with high efficiency equipment. You are getting double duty out of the HE equipment so your summer is cheaper and so is your winter. So going from a seer 10 a/c and straight furnace, you will save a chunk of money.

As in my prior post, I paid $700 (or less) this winter for 4000 square feet with 34 large windows. That might be the equivalent of you paying $400 for the entire winter - might I ask what you paid this year? This is with straight heat pump upstairs and dual fuel downstairs. I suspect I might have saved $50 if I had dual fuel upstairs also but this winter was exceptionally cold.

a quick picture of Greensboro climate provided by Trane website

Climate averages for: GREENSBORO, NC, 27401
Hot weather Cold weather
Average days per year above 75: 153 Average days per year below 40: 31
Average high temperature: 87.6 Average low temperature: 37.7

just averages. this past winter was brutal for the Southeast.

busdriver... good point about the temp swings comparing HP to gas furnace. I think everyone would be happy with the HP. I keep winter t'stat set at 70*F and summer set at 75*F. But we would still have the gas furnace and a/c for downstairs, fwiw.

tigerdunes... yes, it would be placed in the unheated attic. But the thought of sending 15% more cash up the exhaust concerned me... until david_cary put it in perspective. Also, I hope I answered your outside condenser question in the summary below. Your SV80 and XR15HP suggestion may be very attractive. I'll have to check with my Trane guy. I'll lose the gas rebate, but suspect the equipment savings will more than make up for that loss.

david_cary... your post greatly helped with perspective. To this point, I had not been able to get a handle on unit cost vs operational costs. With those numbers in mind, I have no problem staying with an 80% furnace... but I want to take maximum advantage of all available credits and rebates that make sense.

I'll summarize various proposals at the end of this post. Meanwhile, there's a link to our gas usage over the past year in $$ and therms. I'd post the pic, but forgot how to do that here at GW.

Yes, I do want a system that qualifies for the TC... plus these other rebates too, if applicable:
$300 Piedmont Natural Gas for AFUE 90 or higher.
$400 City of High Point electric rebate for HP with 14 SEER minimum.
$whatever mfg rebates are in effect.

I should be able to take advantage of both the gas and electric rebate with the right furnace and a HP, but I see now that it may not be practical/economical to use the 95% furnace.

Is a VS blower desirable? Multispeed? Should I get a t'stat that controls the blower in summer for humidity control?

Everyone has quoted a 95% furnace at my request. One contractor wanted a signed waiver to put it in the attic. Another said they could insulate the short drain line (about 3 ft long) to where it dives into the attic floor.

Here's what I have thus far with costs before any credits or rebates (and after credits and rebates). 4a is the only HP quote I have thus far as I learned about that option late in the proposal process.

1) Goodman SSX160241
1) Goodman MVH950453BX - $5900 (4100)
run new lines outside with cover if needed

2) Trane XR13
2) Trane XV95-60 - $6300 (4400)
run new lines outside with cover

3) Goodman SSX14024
3) Goodman GMV95070 - $6209 (4409)

3a) Goodman DSX1624
3a) Goodman GMV95070 - $6609 (4809)
run new lines outside if needed

4) Carrier 58mvc060
4) Carrier 24APA524 - 6847 (4647)

4a) Carrier 58mvc060
4a) Carrier 25hpa524 - 7631 (4931)
sweat new line to old and pull through.. no outside lines. (I like this option as it keeps the new lines hidden) My lines run on the outside wall then across the attic to the furnace/coil.

I didn't bother with the Lennox proposal as it was so high.
Same with the Carrier proposals that use the Infinity a/c or HP.

I have no particular brand loyalty or leanings other than Ruud/Rheem which I have not quoted yet (they fare better in CR reliability ratings). I've heard the important part is the installation... not the equipment. But I have no way to qualify the installers other than word of mouth... which is sorta limited.

Here is a link that might be useful: Gas usage

I am not trained in HVAC. My posts on this forum are based on user experience or on application of the limited knowledge of the physics involved. I am glad for the post about the potential problem of freezing of the condensate of high efficiency furnaces. New one to me, but certainly legitimate.
I am posting a link to what may be the very finest installer of Trane equipment in this end of NC. Kevin Midkiff. He is a bit far from you, but does travel even farther on occasion.

Here is a link that might be useful: Pilot

Thanks. I appreciate that referral although I would prefer to keep it more local, if possible.

Speaking of Pilot Mountain (from your link), that's one heck of a climb on a bicycle! But I digress. ;-)

I just learned that my preferred option of pulling the new lines through the existing location may not be practical. I forgot about the insulation on the lines. I'm not sure that would survive being pulled by the old line through whatever orifices needed to get from the furnace down to the HP.

Oh well.

I'm getting mixed information about putting 90+ gas furnaces in an unheated attic due to concerns about freezing of the drain line.

Some contractors say it's no problem... others want a signed waiver to install a 90+ furnace in the attic due to the potential for water damage.

I have quotes that are pretty much a wash between an 80% VS furnace and a 95% VS furnace. Obviously, I prefer the higher efficiency one, all else being equal but sure don't want to risk having water damage.

For instance:

95% Carrier system
58MVC060 Infinity 95%AFUE VS Gas Furnace 60K BTU
25HPA524 Performance R410A 15 SEER 2 Ton HP
CSPHP3017ATA HI-EFF R410A Evaporator coil
Carrier Infinity thermostat
new lineset
$7631 before rebates and credits
$4937 after R&C

80% Carrier system
58CVA070-12 Infinity VS gas furnace
25HPA524 Performance R410A 15 SEER 2 Ton HP
CSPHP3017ATA HI-EFF R410A Evaporator coil
Carrier Infinity thermostat
new lineset
$7190 before R&C
$4790 after R&C (loses $300 gas rebate)

Which would be the best option from these choices? Any alternative equipment suggestions?

Lennox systems are about $1k to $1.5k more.
Goodman systems are about $600 more.
The differences are largely due to Carrier equipment rebates and a $300 10 year labor warranty on the Goodmans.

speedlever

I would not put a Goodman in my dog's house.

I personally think a high eff HP with air handler and strip heat is the best choice assuming you have breaker panel capacity.

However let's look at the two Carrier quotes.

option #1 with Carrier three stg furnace and Performance HP is overkill for NC area/climate. Good pricing though. you might substitute the Performance 15 AC condenser for pricing purposes.

option #2 with Carrier 80% eff two stg Infinity furnace paired with Performance HP is good choice.

I realize the pricing is close. However with the freezing issue, I would err on the side of safety.

two things come to mind.

1. ask for the AHRI matching number for each system. I did not see a matching number for the 80% eff Carrier system.

2. how comfortable are you with a high eff 95% condensing furnace in your attic?

at the very least, you should include a 4-5" pleated filter media cabinet with either system for indoor air quality and to protect blower motor and ecap coil.

IMO

tigerdunes,

Thanks for your input.

I posted some incorrect info on option 2. The correct coil should be:
CNPHP3117ATA with the 58CVA070-12 Infinity VS gas furnace
instead of:
CSPHP3017ATA HI-EFF R410A Evaporator coil.

Regarding option with with AC instead of a HP, I have this information:
58MVC060 95% VS furnace
24APA524 15 SEER
CSPHP2112ATA evap coil
inf t'stat
$6847 before C&R ($4647 after C&R)

So the AC option is about $150-$300 less than the HP options, mainly due to equipment rebates and an additional electric rebate.

From a conservative perspective, I'd swing to option 2... but hate to give up that 95% furnace for so little difference in price! The Carrier contractor says he doesn't see any problem with installing the 90+ in the attic, since the line is only 2-3' and goes down an interior wall. I wish the 80% option was significantly cheaper so as to make the conservative choice easier to make.

I'll check on the addition of a pleated filter media cabinet, but am not sure I'll be happy with the additional cost. We don't currently have issues with indoor air quality and haven't had issues with the existing blower motor. But maybe the new system is different in that regard?

Regarding the heat strips.. are you suggesting getting rid of the gas heat altogether upstairs and just use a heat pump backed up by heat strips?

Part of the decision process about the heat strips would be evaluating the existing electrical service to be sure that the necessary amperage is available. For example, if the service is 100 amps, adding heat strips might require a service upgrade. Such upgrades might be costly or inconvenient. If it is 200 amps at present, it is virtually certain to be adequate for the additional load.
As an added note, I know of one house with 100 amp service, gas furnace plus central AC. No other gas usage. The location of the electrical panel is unacceptable per latest code, but is "grandfathered". Owner desired to go to heat pump with strip backup and discontinue gas with it's $120.00 annual cost in addition to actual usage. The necessary electrical service upgrade to 200 amps would have involved installing a new panel on the exterior of the house and extending all circuits, including existing ones, to it. Huge panel, unsightly, expensive installation. So they chose heat pump with gas backup and electrical upgrade unnecessary.

or if you have capacity in your breaker panel, a high eff heat pump with VS air handler and backup electric strip- probably a 7.5KW

Regarding the heat strips.. are you suggesting getting rid of the gas heat altogether upstairs and just use a heat pump backed up by heat strips?

speedlever

that's an option but I certainly would not recommend updating your electrical service.

here are the numbers on the two Carrier options.

80% eff furnace
3257591 Active Systems PERFORMANCE 15 PURON HP CARRIER AIR CONDITIONING 25HPA524H31 CNPH*3017A** 58CV(A,X)070-12 23400 12.00 15.00 24000 9.00

95% eff furnace
Pls re-verify coil mdl number for the 95% eff furnace.

I would not leave out a media filter cabinet.

Only you can decide about the attic freezing issue. Rely on dealer for his experience and advice.

IMO

The ahri matching number for the 80% system is: 3687416. The ahri matching number for the 95% system is: 3686901.

I'm tossing the all electric option... too much hassle. (agreed, bus_driver!)

The coil model for the 95% furnace/HP is: CSPHP3017ATA
The coil model for the 95% furnace/AC is: CSPHP2112ATA
The coil model for the 80% furnace/HP is: CNPHP3117ATA

The Carrier contractor suggests that I use the high efficiency media type filter made by Honeywell designed for use in an existing filter-bearing return grille. It has a 1" lip on it to catch the grille frame and the filtering portion is 4-5" pleated that sinks into the return box, provided the return box is at least 6" in depth.

What advantage would a media filter cabinet offer over the above?

Here are the ahri numbers for the 80% system:
{{gwi:1558724}}

Uploaded with ImageShack.us

The media filter cabinet adds about $250 to the cost... plus a media filter at $55/change. Is this typically user replaceable?

Seems cheaper than using media filters in all the cold air returns (3x$35/ea) with multiple changes/year as compared to using el cheapo coarse filters in the CARs plus the media filter cabinet at 1 change/year.

Are any particular HVAC brands easier to service than other brands?

Update: today I put in an order for the system 2 posts up under the AHRI number 3867416. In addition, the contractor is including the Honeywell healthy climate hi-eff media air filter.

3687416 Active Systems PERFORMANCE 15 PURON HP CARRIER AIR CONDITIONING 25HPA524H31 CNPH*3117A** 58CV(A,X)070-12 23000 12.50 15.50 24000 8.50

this includeds Infinity stat, correct?

IMO

Yes. Infinity thermostat. Anything else missing?

Installation is next Tuesday.

Here are a couple of pics of the new system.

You can see that the new HP is huge compared to the old A/C unit. And the attic installation was tight too.

{{gwi:1558725}}

{{gwi:1558726}}

Here's the old attic installation:

{{gwi:1558727}}