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  1. #1
    Senior Member himespau's Avatar
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    any hvac experts (or others with furnace opinions)?

    As I posted in another thread, I'm trying to buy a house, but we seem to keep picking lemons (first house we had inspected after our offer was accepted appears to be sinking into the ground and the foundation cracking). The current choice needs some work on the windows (some wood swelling/degrading, seals going) and radon mitigation, but the main problem our inspection revealed is that the furnace is shot. The way these things work is, when the inspector finds something like this, you either walk away or you negotiate with the seller to either replace the furnace or give you a credit equal to replacement so you can replace it yourself. Getting the credit is probably preferred so you make sure you can get something you like, not the cheapest possible thing the seller can put in there.

    The current furnace is apparently an 80% efficient one. The state will give a small tax credit (I think $250) if you get a new furnace that's 90 or 95% (I'll have to look to see which) efficient. Assuming we can get the seller to give us a credit, is it worth it in long term energy savings to put out the extra cost for the super efficient furnace? I don't know how much more the extra efficient models cost or how long it takes to make the cost back. Would be looking at a forced air gas furnace (based on the ducting that's in there currently).
    Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


  2. #2
    long time visiter Alfster's Avatar
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    Read this article http://www.wisedan.com/furnace. Based on their numbers, it would take 63+ years to make up the purchase of a new high-efficiency furnace. Plus, there is much more that can go wrong with them compared to a simpler mid-efficiency furnace, so you will likely see higher maintenance costs over the years.

    Here's their calculation:
    Your old unit gives you 80 cents worth of heat for each dollar's worth of gas it burns, and 20 cents is wasted. The new unit will give you 92 cents worth of heat for each dollars worth of gas it burns, with 8 cents wasted.

    If your heating bill is currently $1000 a year, $800 worth of the heat is going into your house, and $200 worth is wasted by your old furnace.

    With a new furnace, your house still needs the $800 worth of heat, plus the 8 percent that your new furnace will waste. $800 plus 8% equals $864. That's your new heat bill. You save a whopping $136 a year! That's more like 13% savings, far from 60%.

    At that rate, your new system will pay for itself in only 63.8 years!


    Plug in your own numbers to see if it's worth it .... likely not. Btw, I opted for a mid-efficiency new unit about 4 years ago. Purrs like a kitten

  3. #3
    Senior Member himespau's Avatar
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    Quote Originally Posted by Alfster View Post
    Read this article http://www.wisedan.com/furnace. Based on their numbers, it would take 63+ years to make up the purchase of a new high-efficiency furnace. Plus, there is much more that can go wrong with them compared to a simpler mid-efficiency furnace, so you will likely see higher maintenance costs over the years.

    Here's their calculation:
    Your old unit gives you 80 cents worth of heat for each dollar's worth of gas it burns, and 20 cents is wasted. The new unit will give you 92 cents worth of heat for each dollars worth of gas it burns, with 8 cents wasted.

    If your heating bill is currently $1000 a year, $800 worth of the heat is going into your house, and $200 worth is wasted by your old furnace.

    With a new furnace, your house still needs the $800 worth of heat, plus the 8 percent that your new furnace will waste. $800 plus 8% equals $864. That's your new heat bill. You save a whopping $136 a year! That's more like 13% savings, far from 60%.

    At that rate, your new system will pay for itself in only 63.8 years!


    Plug in your own numbers to see if it's worth it .... likely not. Btw, I opted for a mid-efficiency new unit about 4 years ago. Purrs like a kitten
    The problem with those calculations is that they're assuming you're going to be replacing a perfectly functional 80% efficient furnace with a 92% efficient furnace just to save money. In my case, the furnace is shot. There are cracks in the heat exchangers, so it's going to be soon leaking carbon monoxide and being a fire risk. It HAS to be replaced. The question is just whether the money savings in energy usage is worth it in extra cost for the furnace. I guess it depends on how much you spend on heat, which I don't know as I'm moving to a new region.
    Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


  4. #4
    long time visiter Alfster's Avatar
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    Quote Originally Posted by himespau View Post
    The problem with those calculations is that they're assuming you're going to be replacing a perfectly functional 80% efficient furnace with a 92% efficient furnace just to save money. In my case, the furnace is shot. There are cracks in the heat exchangers, so it's going to be soon leaking carbon monoxide and being a fire risk. It HAS to be replaced. The question is just whether the money savings in energy usage is worth it in extra cost for the furnace. I guess it depends on how much you spend on heat, which I don't know as I'm moving to a new region.
    It can also be used to compare a new mid-efficiency furnace running-costs to a new high-efficiency furnace. Factor in the purchase price difference, and you'll be able to calculate how long it would take to make up the difference in purchase costs. Since you have to replace it, I'm assuming this is the comparison you need to be able to do.

  5. #5
    Super Moderator no1mad's Avatar
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    I was going to suggest contacting the soon to be your new utility provider about any rebates or credits, but a quick Google search shows LG&E (electric) and KU (gas) are in cahoots to promote heat pumps. Depending on if you will have central a/c and what kind of shape that is in, you might want to look into if a heat pump would work for you.

    Note: I believe you stated that you're relocating to Louisville, KY. The Realtor that you are working with will be able to tell you exactly what utility companies you will have to deal with.

  6. #6
    Senior Member himespau's Avatar
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    So what's the difference between a heat pump and normal furnace?

    Yep, moving to Louisville.

    And Alfster, that's sort of what I was asking. Since I know nothing about the relative costs of either system, I didn't know if someone could tell offhand where the point of diminishing returns was. If the high efficiency model is only say a grand more (and I get the $250 tax credit for getting it) and I save say $100 a year on my heating costs (a bit less than in the example posted due to the difference between posted and actual efficiency) then I'd have made up the difference in 7-8 years and the rest of the life of the furnace is just gravy (well unless that bit about extra maintenance costs is true and needs to be factored in). I've never heard of the older 80% natural gas furnaces lasting much beyond 20 years unlike his suggestion that they'd last forever. Now old boiler furnaces using heating oil, some of those do last forever, but those suckers are different.

    And since I'll have a/c (assuming that isn't shot as well - the inspector said he couldn't test it because it was below 60 degrees outside and that would damage the system but all the fittings looked ok), I'm sure that same $1000 in weatherproofing might provide more energy savings, but that's something that can be done at any time down the road. This is sort of a one time shot at getting a more efficient furnace and was just checking in to see if that'd be worth it.
    Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


  7. #7
    Pwnerer Wordbiker's Avatar
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    I didn't even have a furnace until 8 years ago when I installed one. Went with the high efficiency unit, and this year...it tanked. My friend that checked it out found two bad pressure switches and a bad main board. The cost for parts alone is $650. He also said that these units last on average...you guessed it...8 years before requiring repairs. It's almost as if they built a self-destruct mechanism into them. I'm burning wood until I can afford to fix it.
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    Administrator CbadRider's Avatar
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    I got a new furnace last year through Costco. I looked into getting a high-efficiency model, but my house is only 1500sf and the winters here aren't that bad. I got the mid-grade one and it was quite a bit cheaper to run than the previous furnace that was 30 years old and had corroded and become very inefficient.
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  9. #9
    Old Fogy
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    "So what's the difference between a heat pump and normal furnace?"
    A heat pump is basically a reversible air conditioner.

  10. #10
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    Quote Originally Posted by himespau View Post
    And since I'll have a/c (assuming that isn't shot as well - the inspector said he couldn't test it because it was below 60 degrees outside and that would damage the system but all the fittings looked ok), I'm sure that same $1000 in weatherproofing might provide more energy savings, but that's something that can be done at any time down the road. This is sort of a one time shot at getting a more efficient furnace and was just checking in to see if that'd be worth it.
    What kind of central a/c unit does it have? Is it a heat pump? If you have a heat pump, the furnace is just a backup source for when it's too cold to efficiently run the heat pump. Paradoxically, that limited use makes it that much more efficient to go w/ a high efficiency furnace because you only use it to put out large amounts of BTUs (and therefore w/ a high efficiency furnace you send fewer of them out the chimney)

    For pricing, there is more than just the price of the furnace though; you might also need to look into lining the chimney, high-efficiency furnace exhaust is more corrosive and will eat up an unlined chimney.

    But finally, I think looking at how long it takes a furnace to 'pay for itself' is a red herring. How long do you expect your dining room table to take to pay for itself? What about your living room sofa? If you need it, buy it at a price you can afford. Anything else is financialized rationalization that doesn't actually put any more (or less) money into your pocket.

  11. #11
    Senior Member himespau's Avatar
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    Thanks for the advice all. Not sure it's going to matter as the seller seems to be trying to weasel out of our escrow contract, claiming we never signed and accepted his counter offer even though his agent has it attached to a sent e-mail to him over a week ago and we've had our money in with her for a week. It's an odd response to getting our inspection report. If he really wanted out of escrow, all he'd have to do would be to refuse to fix the things we say need fixing (furnace, radon, windows, plumbing), and we'd have to walk. Since the inspections have already been done and sent to him, he can't claim he doesn't know about them and skip putting the problems on the disclosure forms if he relists the house, so trying to back out in this way is just strange.

    Hardy (like the nickname, by the way - fellow biologist?), I get what you're saying about it not paying for itself in that it'll never actually put money back in my pocket, but I do think that, unlike a dining room table, if it does save me money in the long run, it'll allow me to keep money in my pocket that I otherwise would have spent. On the other hand, it's looking like there are a lot of ancillary costs associated with going high efficiency and it will probably need replacing sooner. Some of the higher costs (lining the chimney if not already done, etc.) might be palatable if it was going to provide other benefits like being more environmentally friendly, but, if I'm going to have to be replacing it more frequently, that's going to eat up a lot of resources too (along with the environmental costs of mining the parts), so I'm not sure how much of a net environmental benefit that would provide. You all bring up a lot of things I hadn't considered. I'll keep them in mind if we stay on the road to buying this house.
    Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


  12. #12
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    Quote Originally Posted by himespau View Post
    The problem with those calculations is that they're assuming you're going to be replacing a perfectly functional 80% efficient furnace with a 92% efficient furnace just to save money. In my case, the furnace is shot. There are cracks in the heat exchangers, so it's going to be soon leaking carbon monoxide and being a fire risk. It HAS to be replaced. The question is just whether the money savings in energy usage is worth it in extra cost for the furnace. I guess it depends on how much you spend on heat, which I don't know as I'm moving to a new region.
    Shoot a PM to Dudelsack, who lives in Louisville and may be able to give you a clue as to heating costs.
    Dream. Dare. Do.

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    The efficiency-versus-cost issue is a red-herring if the price of the property is negotiated down to compensate for the installation of the more efficient replacement furnace. That way, every saving every year will stay in the OP's pocket.

    The heat pump solution, however, seems to be a likely option, depending on the configuration of the floor plan.
    Dream. Dare. Do.

  14. #14
    Senior Member himespau's Avatar
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    Quote Originally Posted by Rowan View Post
    Shoot a PM to Dudelsack, who lives in Louisville and may be able to give you a clue as to heating costs.
    That's a good idea. I have a rough idea from another house we looked at (a little smaller and it did use an electric heat pump thing instead of a furnace), but I'm not sure it's going to matter as the seller of this house is being so weird. We'll have to see. If we get anything, it'll only be a credit equal to the cost of replacing the current furnace with another 80% efficient similar model. If it goes through, I'll have to ask the guy who quoted the price for the work how much extra a more efficient model would run and go from there. With the guy flaking out and seeming to be trying to back out of the contract for no real reason (other than maybe changing his mind and not wanting to sell the house anymore, we'll have to see.
    Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


  15. #15
    Old Fogy
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    Stainless liners in chimneys are expensive. However, most high efficiency furnaces are installed with horizontal PVC vents, which are cheap to buy, although sometimes difficult to install.

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    Quote Originally Posted by waldowales View Post
    Stainless liners in chimneys are expensive. However, most high efficiency furnaces are installed with horizontal PVC vents, which are cheap to buy, although sometimes difficult to install.
    The condition of the lining of the chimney is a factor when installing any heating/water heater unit. There are newer systems for adding a flexible metal liner, but weigh the costs, as well as check local code for compliance. You can also get what is know as a direct venting furnace (common to co-ops and condo's). I have a DV gas boiler heating a 3 zone 1600 sq. ft. house, as well as DV hot water heater that were installed as the cost of installing a chimney liner was exorbitant. My units vent thru the sill plate above the foundation. The vents typically cannot be located within 5ft of a door or window according to what I've read, so that dictates unit placement. The venting is fan powered so would need electrical power (a factor if you lose electrical service in a storm). Very efficient units though.

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