confused- heat pump vs. standard A/C

14 years ago

Hi all,

I need more help since I've been in the process of collecting bids. I was initially pretty well sold on getting a new 80% variable speed furnace with a high efficiency heat pump (it seems like everyone is pushing for the heat pump option) but today a Trane dealer also presented the option of a 95% variable speed furnace with an A/C unit. I'd like to know what's best given my home, climate, and electricity/gas rates.

I live in the Seattle Tacoma area where I will be using heat a whole lot more than cooling. The summers appear to be getting warmer each year, but avg. temps in the summer are in the 70's, with a few days in the 80's and 90's. This year so far, we've been getting a few more hotter days (high 80's up to 103!). Winter lows on average are maybe low 40's during the day and down to the high 20's/low 30's at night. We had a very cold winter last year down to 18 degrees.

My home is 11 y/o, 2100 sq. feet. Right now I only have a gas furnace, builder's grade. Only one load calc has been done with the following results, based on avg. outdoor summer temps of 80 and outdoor winter temps of 26: BTU heating of 26,921, and BTU cooling of 16,823. My prices for electricity based on my most recent utility statement are $.084772 Per KWH (for the first 600 KWH) and then $.102581 Per KWH for over 600 KWH. Price of gas are $.87388 Per Therm, but the bill also indicated a cost of gas delivery of $.34039 Per Therm.

The Trane dealer today gave me estimates for 2 different systems:

Heat pump and furnace would include:

XV-80 HP TDD0G0R9V3F furnace

XL16i Heat pump 4TWX603661000A (he's going to check if the XL15i would be just as efficient although it's a single stage)

TCONT900 thermostat

All accompanying coils (he didn't provide model #'s)

This system is $9855 with a $500 Trane rebate but before taxes and federal tax credit.

The furnace and A/C unit includes:

XV95 furnace TDH2B060A9V3VA

XR15 A/C 4TTR403061000A

TCON802 Thermostate

All accompanying coils (again, no model #'s)

This system is $7925 with the $5000 Trane rebate but before taxes and federal tax credit.

Obviously there's a big savings with the A/C option. The salesman told me he has a heat pump in his all-electric home, but if he had gas he would go for the A/C set up.

Thoughts and suggestions? Thanks again so much for the advice!

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Comments (10)

jakethewonderdog
14 years ago
In general, I believe that a furnace is more reliable, last longer and easier and cheaper to repair than a refrigerant system (such as a heat pump).

Particularly if I had gas as an option, I think the furnace/AC option is better than a heat pump. You will use the AC a couple of weeks in the summer, and that's all.
baldloonie
14 years ago
My calculations say this:

Cost of 1 million BTUs put in the house:

Good heat pump at 32Â° out $9.16

95% furnace, $12.74

So how often do you get below 32Â°? If a lot, might be worth looking more the gas route. But since I'd guess not that often below freezing, I'd sure save the money and go 80/HP.
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Tiger, my conflict is because I know I am being overcharged due to the rebate program. I resent that and just want a fair deal. I know that I am "losing" part of my rebate to the contractor who leaves me with just enough to make me think its a good deal because of the great financing. It is the financing which has made me decide to do it, that plus the attic sealing and insulation which I would probably not otherwise do. I ask a lot of questions because I like to be informed. Not really sure if heat pump will be worth it here either. They claim my energy "savings" will be an additional 5% or so, though a contractor not in the program told me they will manipulate numbers to make it work. Because the heat pump is slightly more efficient in my case I get a $1000 higher rebate, so my net cost is Actually the same. This is because the non hp option uses a more efficient hot water heater (needed for the program) that they are charging 400 more for, AND the rebate is 1000 lower. With those 2 choices the hp makes sense. It would make even more sense if the upgrade cost was not $1500. I could go tankless with non hp, get the full rebate, but cost is 500 more than hp. Figured I am more likely to see savings on the hp so not spending the extra 500. Anyway, after this heat wave i totally see the value in getting my attic done, so even though I will not be fully realizing the amazing 5000 rebate I will probably do it. My ac, in it's 16th year, had a hard time getting below 75 on these hot days, even the ones only in the low 90's. I'm sure it will be going in the next year or two. Neighbor paid 9200 beforerebates for a Lennox xc17 with an 80% furnace. I figure my higher eff furnace would cost more and so would a heat pump, but I know Amana would be cheaper than Lennox, based on that i think the 9200 is a reasonable cost to compare.... I will be spending about 11k for the Amana system, with a new power vent hwh and insulation and air sealing. I think that is reasonable (though I'd prefer a different brand ). I also think my price should be closer to 9k after rebates and that I am getting "only" 2000-2500 value of the 5000 rebate. I am also getting excellent financing. The dealer did do my audit and spend time getting my estimates together and revising them.....not 2500 worth of work. Decided to just do it if I can get the price dif between hp and not-hp lowered. I know you think I'm a pain, but what would you do? Would you accept a price you know is very high or keep asking questions? You have to,admit the price of 11800 is very high for Amana Aszc16 and Amvc95. (4 ton, 90k btu) Does any of that explain why I am conflicted? I am not normally difficult, only when I sense something is not right. Lucky for me when I buy cars there are sites to tell me what is fair and reasonable....being educated is my best option. I could just get an hvac but I don't see us ever forking out the $ for the attic work,separately, and I know it should be done. The attic must be done to get rebate so may as well do it. I hope you can see I am moving toward a decision. I don't want to bother getting more prices. I trust this co and now want to get the best deal that is reasonable from them. Just really wondering at this point how much wiggle room there might be on the Amana set up. The carrier is 2k more and I just don't see the value in it.
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tigerdunes
14 years ago
DRCINCY

you have received excellent advice as usual from Baldloonie.

I would also pay close attention to SpeedyMonk's post on Hvac Talk forum.

I would not have Trane's XL16i mdl either in AC or HP condensor. too problematic.

Your first quote with the XV80 furnace does not qualify for the tax credit.

If you do decide on an 80% VS furnace paired with a high eff HP, I would look at Carrier or Bryant. Trane is clearly falling behind in efficiency with dual fuel systems.

I would also include a new refrigerant lineset and a 4-5" pleated media filter cabinet.

IMO

Here is a link that might be useful: Your HVAC Talk forum thread
jake2007
14 years ago
Perhaps there is a cost savings in energy- again depends on the weather. But I don't see Heat Pumps lasting as long as a furnace or operating with as few repairs.

A compressor replacement after 6 years pretty much eliminates any savings in energy.
speedymonk
14 years ago
My first Trane HP was purchased in 1989. I sold the home is 2006. It's still there. Standard service and no problems.

I expect the same out of my new Trane XL14i that I requested for my custom home built and occupied in 2007. I did buy the extended parts and labor warranty for $500. Cheap insurance.
tigerdunes
14 years ago
for Speedymonk

speedy,

I live in Southeast and also have a dual fuel Trane-same as yours, XL14i(R-410a) paired with an XV90 furnace. I really wanted the XL15i but it was just being introduced and only available in R-22 which I did not want. I probably should have gone with the XV80 furnace but kind of hedged as this was my first experience with a HP. I knew though that all was OK since my wife has never complained about the HP since it most likely performs about 90+% of heating chore based on my area's climate and relatively mild winters. I estimate I used about 60-70 therms of nat gas last winter. Savings over 100% nat gas heating vs heat pump heating est at around 35%.

No regrets with the HP.

Trane though is really falling behind in tax credit qualifying condensors both AC and HPs.

IMO
brickeyee
14 years ago
You can look up degree-days of heating from the national weather service, and even more data giving days below various temperatures.
It is a bit of work to find the data and then handle it, but I have used it along with actual heating bills to double check manual J calculations on older houses.
R value for walls and infiltration losses are a major source of error, and while a blower door test can help with infiltration, it takes an IR camera to get an accurate measurement on losses though old structures.
speedymonk
14 years ago
TigerDunes, I agree with your comments on Trane's performance numbers. Disappointing. Other brands have better heating performance numbers, for sure.

Maybe Trane will have come to its senses in about 20 years when this one runs its course. If not, I will be much better educated on all this when the time comes to replace my current system. I'm just pleased the system does the job the way it was designed.

I'm with you on the 80% furnace. My 90% is overkill for what I used last year. I didn't know at the time.

I do get a slight kick out of going outside in the morning during the heating season and hearing the whir of my HP while seeing that most of the neighbors have gas plumes emitting from their stacks. Changing the compressor lockout made a difference in the bill.
langle1033
14 years ago
I live in Greensboro, North Carolina and I think the winter is mild. I plan to replaced my existing AC/gas furnace system by a heat pump/gas furnace system.

1. Assume that I have very good insulation house, can you guess how much I will save in future heating cost with this replacement?

2. Since the AC/gas heat unit will last longer than the heat pump/gas heat unit, even with the compressor lockout function enable, do you think the energy cost saving will justify for this dis-advantage ?

3. What is the compressor lock out temperature I should use for my area if I go with heat pump replacement ?
speedymonk
14 years ago
I don't necessarily agree that an AC/gas furnace system outlasts a heat pump/gas furnace system. My old place had a split system for 17 years. I sold the place and it's still there three years later.

Concerning the lockouts, it depends on your home insulation, windows, etc. Start at 30 degrees. If it's ok, drop to 25. If it can't keep up, go back to 30 or 35. Whatever works for you in your climate. There 's a balance between cost savings and comfort.

If you use the Honeywell IAQ, the thermostat needs to "learn" the temps and sometimes that takes a week for things to settle in when it gets cold. Give it a chance. I've been pretty happy with my setup. Simple, yet effective.

confused- heat pump vs. standard A/C

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jakethewonderdog

baldloonie

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