80 vs 90 % efficient furnace?

Question

We're in the process of buying a townhome that is being built. we need to decide between a 80% and a 90% energy efficent furnace. Is it worth $1500 to upgrade to the 90% for a 1600 square foot townhome, a middle unit.

Answer 1

From what I've been told it is not worth the investment. My furnace is about 5 years old, efficiency is about 83%. I wouldn't consider changing it unless it were to fail totally.
Try to calculate your payback period on the furnace based on today's energy rates. If you estimate the monthly heating costs, you will be able to calculate the payback period for the 90% efficient furnace. If you recover your money within what you consider to be a reasonable time it could be a good investment.
I suspect you'd be further ahead getting extra insulation in the walls and ceiling, maybe upgrade the windows to higher efficiency.

Answer 2

You definitely have some leverage here. First of all you need to figure out how much extra this is going to cost you. To do this, you need to back your summer time heating cost from your winter time heating cost using the bills from at least the last 12 months. If you can get a good handle on the bill during June, July, August, you should be able to come up with an average cost without heat. Back that amount out for all 12 months and assume that the remainder is the cost of heat. I think you can probably assume that your old furnace was 80% efficient, at least for the purpose of this calculation. If you then multiply that figure by 0.112 you will get your savings with 90% efficiency. (You save slightly more than 10%. I won't go into the details of the calc that shows that.) That will give you your savings per year. Personally I'd multiply that by 10 for a 10 year payout, and then provide escallation of 5% per year, which may be an underestimate, but it's anyone's guess. So savings would be as follows: Year 1 savings= (savings/Yr)*1.05 Year 2 savings= (savings/Yr)*1.05*1.05 Year 3 savings= (savings/Yr)*1.05*1.05*1.05 and so on until year 10 This would than give you a feel for your loss for 10 years. I tossed this into a spreadsheet and came up with the following: Yearly_____ Savings _____ 10 Yr Savings Cost _____ 1st yr 1000 _____ 112_____ 1479 800 _____ 90 _____ 1183 600 _____ 67 _____ 887 400 _____ 45 _____ 592 200 _____ 22 _____ 295 (This Yahoo thing apparently doesn't like tabular formats, sorry for the dashes.) This would suggest that if your yearly heating cost is under $550 or so you could be better off with the $800. Remember that this is all calculated on a 10 year payback. There is one other factor, if you are thinking of selling your house at any time in the next 10 years of so, being able to advertize a 90% efficient furnace may be worth money also, perhaps even more than $800 all by itself. (In Minnesota a 90% efficiency furnace is worth mentioning and worth money when selling a house. In California a 14SEER AC is probably worth advertizing. Don't know about heating units in California.) You could potentially tack the $800 on to any of the above figures that apply and go for that amount from the company that installed the wrong one with an actual basis for your demand.

Answer 3

I doubt any contractor or builder would agree with me, but they will not be living in this house. I don`t remember which furnace is 80 or 90.
First off I think there is too much difference in the price, believe I would ask around a bit.

Here is my story, for what its worth. 20 years ago we were living in an old antebellum home, 3600 Sq Ft. We had a plain old Natural Gas furnace, replaced it with a 2 pipe,(2inch plastic in and 2 inch plastic out) furnace. Went from a 175000 BTU to a 75000. Reduced my gas bill about $250.00 per year. But more important we were warm all over the house.

10 yrs ago we sold it, bought a 1900 ranch, with a 5 year old Lennox. Used it 2 years, replaced it with another 2 pipe and cut the BTU rating 50 I am thinking. Gas per cu ft as you know has taken a big jump the last 8 years. My annual gas bill is with in pocket change now as it was 10 years ago.

In the last 4 years my nearest 6 neighbors have followed suit.

We do open an outside door about every day, and let in some fresh air, with the 2 pipe the furnace is burning out side air.

This helps much, no cold air coming in that needs to be heated.

You do what ever rocks your boat, but I think you can tell I have no regrets and would do it all over again.

Answer 4

The answer to that question is how long will you live in the townhouse. If its 5 years or less, the 80% will do the job. If its longer than definately go the 90% route. The savings in fuel consumption will make up the extra investment.
You should also ask if the 90% line offers a 2 stage gas control valve or a variable speed blower. Both are better than a standard 90%.

Answer 5

an 80 pecent vs 90 percent, having just put an 80 percent in, with this cold winter we have had, I think I would have gone wiith the 90 percent 10 percent larger than what i needed.

Answer 6

The 90% will save you $$ gas wise but will raise your electric bill considerably.

Answer 7

Only if you are planning on staying atleast 10 years to get your money back....

Answer 8

space heater 100% efficient