If price equal, any reason not to go HP vs. AC?

OH070September 8, 2011

Living in northeast Ohio, looking for a new system (old compressor shorted out.) Getting quotes now.

Right now, there are decent rebates on certain better HP units and additional incentives ($400) from the electric company. Including rebates/incentives, the price of the 2-stage 16+ SEER HP is about equal to the price of a 2-stage 16+ SEER AC unit.

My question: With prices equal (or nearly so), is there any reason to NOT go the HP route? In our case (NE Ohio, pretty cold winters,) we're planning to pair with a high-efficiency multi-stage or modulation furnace (don't know if that makes a difference in the answer or not.) Since we don't have a crystal ball to know what electric/gas rates will be 5 years from now, we like having options on heating.

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Did you check for operating costs with the US DOE worksheets? No crystal ball is needed! The real experts might want more information about the specific equipment.

    Bookmark   September 8, 2011 at 6:52PM
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My thinking is that regardless of what the heating costs are, having the option of heating either way (i.e. HP + furnace) is an advantage. If there's no difference in price between similar AC & HP units, why not get the HP? We can always use it just as an AC and run the high eff furnace for all heating if NG stays so cheap. But who knows what the prices will be 5 years from now? I like the added flexibility.

Maybe there's a reliability issue, or an efficiency issue, or some other issue to consider with HP's that I'm not aware of? That's why I'm asking before we decide.

Thanks for all opinions!

    Bookmark   September 8, 2011 at 7:51PM
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If natural gas gets expensive you have another option with the heatpump. I personally like to run the heatpump in milder temps (around 30 or 35 and above).

I can't think of a good reason not to upgrade to the heatpump if its the same price.

I think the heatpump can still last as long as straight a/c if you have the gas furnace as backup. You will still be using the gas heat during the bitter cold and hard cold that would keep a heatpump running constantly in our climate.

    Bookmark   September 9, 2011 at 7:29AM
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What are your nat gas and electric rates including all related charges within your bill?

I want to see the AHRI matching number for the systems you are considering.

For your area/climate, I would not have a HP in a dual fuel system that did not have electronic demand defrost feature.

Post back.


    Bookmark   September 9, 2011 at 7:57AM
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last month $187.16 for 1,743 KWH (=$0.107/KWH)

last month $32.52 for 1.5 MCF (=$21.68/MCF, but a low usage month - other fees overwhelm the number)

Feb 2011 (peak usage for us) $261.15 for 24.8 MCF (=$10.53/MCF)

Home is 47-yr old 2,000 sq ft split with known insulation & airflow issues on 2nd floor (which we will try to address - getting insulation quotes & discussing better airflow/return options.) So far, vendors doing the calcs (the only ones we're pursuing) are sizing 60,000-80,000 BTU furnaces and 2 1/2 or 3 ton AC units.

Will post some quotes for comparison later -- they're coming in as I type, but not all are including model numbers/AHRI matching numbers, so we're awaiting follow ups. All are Rheem/Ruud or Trane/AmStd systems.

Thank you all again for the excellent help. It can be very confusing trying to digest all the new technology/ratings/options when you only do it once every 20 years!

    Bookmark   September 9, 2011 at 8:25AM
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What size furnace and efficiency along with AC or you replacing?

What are your comfort issues with existing HVAC?

I wouldn't pursue a dual fuel system if you are going with a full modulating furnace.

I'll run some preliminary numbers on Electric HP VS nat gas furnace to let you know if any operating cost advantage.

I would want a whole house air filter cabinet.


    Bookmark   September 9, 2011 at 8:43AM
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Replacing a Lennox G20 Whisperheat 100,000 BTU 78% furnace (16 yrs old) and Lennox 12ACB 2 1/2 ton AC (don't have the exact model numbers handy, A/C is also 16 yrs and I think 10 SEER.) Compressor shorted out. Thankfully it's not very hot here so we have a little time to decide.

We've been looking at both 2-stage and modulating furnaces. What issues are there with modulating furnaces & HP's?

We currently have an Aprilaire 2200 filter & model 600 bypass humidifier, both of which we were thinking of reinstalling with the new system (humidifier has new water panels, tray & feed tube assembly.)

Is it worth upgrading to a power humidifier (like Aprilaire 700?) We have a very tight space as it is, so wouldn't mind losing some of the piping required with our 600. We can live with it though, as the high eff furnaces are generally not as wide (17 1/2 vs. our current 21".)

The biggest comfort issue with current system is upstairs. The highest part of the house (it's a split) still has original terrible insulation in that attic (we plan to address this now.) For a double whammy, the circulation upstairs is also poor (registers on floor, return on floor in hallway. Cold air seems to go right across the bedroom floor and back down without cooling rooms.) We run fans upstairs in the summer and still see 6-8-10 degree temp differences. We're thinking of running duct work up through the side of one of the closets to get to the attic space and put returns in each ceiling (will that help with air flow/circulation?)

Thanks again for everyone's help! Will post some quotes once we have the info.

    Bookmark   September 9, 2011 at 1:35PM
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HP's typically are built tougher than their A/C counterparts. They can run quite a long time. Keep in mind that in NE ohio climate, the A/C only gets worked for about 3 months of the year and typically not constantly. A heatpump in Northern Ohio climate can be used in the spring and fall in addition to summer. It shouldn't be problematic. These have been around a long time. Get a decent brand and a good installer.

I"m not too familiar with the problems of modulating furnaces. You might be going overkill if your getting a modulating furnace along with the heatpump. I would think a 2-stage furnace would be fine. The soft-heat of the heatpump would be your first stage for when its not very cold out.

    Bookmark   September 9, 2011 at 3:21PM
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I ran some numbers of HP heating versus nat gas heating.

Using an HSPF eff of 9 (2.75 COP) and 95% eff on gas furnace, there is no operating cost advantage of a HP in dual fuel system.

For your area/climate, I would look at the full modulating furnaces that modulate both up and down. Brands to consider are Trane/AmStd and York/Luxaire. Lennox does not modulate both up and down, only up. Because of that I would not consider them. One other point is that the York/Luxaire mod has higher eff at 97-98 eff plus does not require a special thermostat to operate the furnace which is nice plus. All of these are reliable and I don't know of any problems.


    Bookmark   September 9, 2011 at 3:36PM
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Here are a few systems under consideration: All include repositioning existing Aprilaire 600 (humidifier) & leaving Aprilaire 2200 filter in place, condensate pump & line (weâÂÂve had problems with the gravity piping so will try pumping,) minor ductwork/dampers to improve flow/balance, new refrigerant lines, 10 (or 12) year parts and labor warranty (weâÂÂre extending labor agreements on any system so included that in the quotes.) More significant ductwork/insulation projects are being quoted separately. I did not include any IRS rebates, as they should be the same for each of these systems (will confirm before choosing.)

Furnace: AmStd Platinum ZV AUHMB080ACV3
ID/Coil: 4TXCB036BC3
Heat Pump: AmStd Platinum XM 4A6H6036E1
ARI ref: 3853896
Tstat: AZONE950
Price (after mfg rebates/incentives): $8,015

Furnace: AmStd Platinum ZV AUHMB080ACV3
ID/Coil: 4TXCB036BC3
A/C: AmStd Platinum XM 4A7A6036E1
ARI ref: 3851318
Tstat: AZONE950
Price (after mfg rebates/incentives): $7,829

Furnace: Trane XC-95m TUHMB080ACV3VA
ID/Coil: ??? (Trane matching, waiting for number)
A/C: Trane XL-16i 4TTX6036
ARI ref: ??
Tstat: TCONT602 (?, need to confirm)
Price (after mfg rebates/incentives): $7,700

Furnace: Ruud Achiever 90+ UGFD-07EMCKS
ID/Coil: Ruud ??
A/C: Ruud Ultra UARL-036JEZ
ARI ref: ??
Tstat: ?? (programmable, waiting for model)
Price (after mfg rebates/incentives): $7,750

WeâÂÂre expecting a few more quotes, but these seem (to us) to be quality systems at reasonable prices. Comments/suggestions would be welcome! BTW, I've gone to the site and looked up the ARI info, but have no idea of how to decipher all those numbers! Help on that would be appreciated. Thank you all in advance! This has been so helpful.

    Bookmark   September 9, 2011 at 5:50PM
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Go with quote number one with the heatpump. Thats great equipment. Your sure to be happy. Price is good considering your getting some extra work done.

Run the heatpump at 35 and above. I'm in the same climate as you (NE Ohio). Your COP on the heatpump should be closer to 4 around 47 degrees and pretty close to 3.5 at 35 degree's.

    Bookmark   September 10, 2011 at 8:39AM
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For neohio

Give some supporting documantation on that last statement.

You can't because it is factually incorrect.

As I stated earlier, I ran the numbers of fuel comparison of electric HP versus nat gas heating. It is a wash. And that was at 2.75 COP which the
system quoted is even lower.

Have you looked up the matching #3853896? What is the HSPF efficiency on this configuration? It is 8.5 at 47 degree fah. Do you know how to get
the COP? At 47 degree?

The price of the HP add on is good. However, the performance/eff
numbers along with the electric rate simply don't make dual fuel work.

Based on the info provided, the straight AC with the modulating furnace is the way to go.

One suggestion. OP can call electric utility to see if they offer any special
rate incentive for heat pump heating in a dual fuel connfiguration.


    Bookmark   September 10, 2011 at 10:03AM
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No reduced electrical rates in our area for HP heating (used to be, no longer.)

If I'm reading things correctly, it's better for us to heat the house with a furnace, given current pricing & efficiencies.

However the HP pricing makes it very tempting to put the HP in and only use it for AC now. I have no idea what the price for electricity & gas will be in 5, 10, 15 or 20 years. I might be very happy to have that flexibility down the road when prices change. That insurance policy only costs me a couple hundred dollars... I didn't hesitate for one second paying $300-$400 for the "insurance policy" to extend the labor warranty to 10/12 years. I'm looking at the HP in the same light. I may not ever need it, but it's nice to have.

If we go A/C instead of HP, do you have a preference on the Ruud vs. AmStd vs. Trane quote? Does one give a better bang for the buck, or are they all about the same? FWIW, we were comfortable with the companies providing those quotes, so no preference there.

Also, any comments regarding re-using our existing Aprilaire humidifier vs. replacing with a new model bypass or electric unit? I understand the electric ones can be noisier than the modulating furnace itself (when it's not working hard...can that possibly be true?) No matter what, I'm guessing ANY setup is going to be a "whisper" compared to our single stage, single-speed 100,000 BTU dinosaur!

Any advice/preference/comments on the quoted thermostats?

Again, thank you all for your help!

    Bookmark   September 10, 2011 at 4:27PM
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One point worth noting is that you don't get full BTUs in cooling with the XL16i. You take a haircut of about 2400 BTUs for a three ton condenser. Might mean little but if your cooling load is close, then this might make a difference on the hot days.

You have the facts on this configuration as well as operating cost of HP heating versus nat gas heating. I still believe the mod furnace with HP is overkill and not your best choice.

To the thermostats, you want the AmStd thermostat that allows for full modulation of the furnace. The Trane dealer is quoting the wrong
thermostat if in fact it is the 600 series mdl.

How old is existing humidifier? I would rely on dealer recommendation. Certainly the furnace will be extremely quiet. I would not want a humidifier to step on the furnace from a noise standpoint.

What plans do you have for a whole house air filter cabinet?


    Bookmark   September 11, 2011 at 6:42AM
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Tigerdunes - you seem down on a dual fuel lately. In the past, you have been much more positive. Obviously each situation is different and a modulating furnace tilts the balance.

COPs can be a lot higher than 2.75 - that seems pretty bad for a high efficiency HP.

Obviously NG is really cheap right now but that may change. I think dual fuel is cheap insurance. I went with that 2 years ago when I built and my heating costs are pretty low - but I really don't know what they would have been. I do know my NG bill is around $150 a year and my electric use is 40% below my peers (who use all NG heat) - so I am doing pretty good.

    Bookmark   September 11, 2011 at 6:51AM
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Our current Aprilaire 600 bypass humidifier was installed in 2002 and recently tuned up (2010, new new water panels, tray & feed tube assembly.) One dealer quoting offered to install a newer bypass humidifier, but I was struggling to see any advantage over what we have. I was more curious about the power humidifiers until I heard about the potential noise issue.

We were planning to reuse the Aprilaire 2200 for whole house filtering (we have extra filters and have been happy with the performance.) It can remain in the same place with the new system.

I will check/confirm the thermostat being quoted with the Trane system. I put a question mark in my original post because that didn't seem like the right one to me either.

I know I keep repeating it, but thank you all for your help. I feel like we're in the home stretch now!

    Bookmark   September 11, 2011 at 6:57AM
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Just for the record, I have a dual fuel system about 6 yrs old. It was the right decision for me at the time.

There is a marketplace for nat gas, but certainly not as much with electric.
Nat gas prices have remained steady and in fact have come down. Not true with electric.

And with the advent of modulating furnaces, a heat pump really becomes a larger question.

Simply put, the math does not work as well as it use to. And of course, one's location/climate has to be taken into consideration.

Not down on heat pumps but in many cases the mod furnaces make the addition of a heat pump unnecessary. The idea of leveraging one fuel choice against another while sounding good and a nice sales pitch is more difficult as electric rates advance.

That's my perspective.


    Bookmark   September 11, 2011 at 7:11AM
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The COP on system is about 2.75 in the low to mid 20's fahrenheit. A good high efficiency single stage heatpump should have a COP around 3.7 at 47 degrees. At 35 degrees the COP should be around 3.25.

Heatpumps do great in mildly cold weather (above freezing).

Its true, gas has been cheap, but you never know when it could spike up again.

    Bookmark   September 12, 2011 at 8:23AM
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I just disagree with neohio's numbers on COP. I would like to see the documentation from an independent source.


    Bookmark   September 12, 2011 at 9:13AM
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I'm pretty sure Goodman's website has detailed COP info on all their heatpumps detailed on every 3 degree increment in outside fahrenheit temperature.

    Bookmark   September 12, 2011 at 11:27AM
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I thought we were discussing Trane/AmStd XL16i and Heritage 16 mdls.

Not interested in what Goodman has to say.


    Bookmark   September 12, 2011 at 11:52AM
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I guess I didn't realize trane/amstd xl16's had such a low COP. I though even the low end models would achieve a COP of about 3.5 at 47 degrees.

    Bookmark   September 12, 2011 at 12:24PM
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Follow-up: We decided to go the heat pump route. I realize it's slightly cheaper to heat with natural gas right now, but also remember the days not too long ago (2005, 2008) when natural gas was 3x more expensive. In the end, for less than $200 we added the flexibility to switch over if the pricing warrants. Cheap insurance against future (inevitable) spikes, IMO.

I was thinking of initially setting things up so that the HP & furnace each run about 6 months a year (thinking that will maximize the lifespan of the system with a minimal energy cost increase.) Good idea? Maybe we should just always heat with whatever the lowest cost option is and not worry about how many months each piece of equipment is working?

Anyway, I didn't want to leave without thanking everyone (especially tigerdunes and neohioheatpump, both very active & helpful participants in this thread.) This forum has been an excellent resource, not only for the comments related to our specific situation, but for the wealth of information on virtually any HVAC topic!

    Bookmark   September 13, 2011 at 7:26AM
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Good choice. That extra flexibility is nice. Your idea to run each system for 6 months of the year isn't a bad idea. In our area, typical straight A/C's are completely under utilized. Most people around here spend thousand of dollars on equipment thats barely used 3 months of the year. It makes more sense to spend a little more and have a heatpump that can be used much more.

Does your new system have an outdoor temperature sensor? If you have an outdoor temp sensor, start by running the heatpump when 40 and above. You may end up changing it to run a bit more often (maybe 35 and above). That won't work the heatpump too hard. The heatpump should still last a very long time. I think life would be taken off the heatpump if you ran it at say 20 and above. Which is a very long winter in northern ohio.

    Bookmark   September 13, 2011 at 7:41AM
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Well of course, I respect your decision even though I believe it to be misguided and not supported by facts.

As neohio said, you will need an outdoor sensor connected to your thermostat and furnace.

I certainly would not start at 40 degree on your sensor. At least start at 35 degree and see how that works for you. And anytime you want to shut off the HP, you can do this with the thermostat by going to "emergency" heat setting.


    Bookmark   September 13, 2011 at 7:54AM
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