A friend has a house in the mountains. No A.C. The furnace is as old as the house, probably 1965 or 1970. Are new furnaces more efficient in their use of natural gas, and thus "pay for themselves"? If so, how does one calculate the anticipated savings and pay back period?
Hi, New high efficiency furnaces are as high as 98%. Regardless cost, up here in Canada lagally low to mid efficiency furnace can't be installed on new install. Think your friend's furnace is not even mid efficiency(80%) being that old.
In several modern countries, both fuel and utilities vendors provide sample budgets, sometimes also national laboratories for building standards, efficient energy policies etc.
Older furnaces can be from 50% to 70% efficient while newer ones are over 90%. If you replace a 70% with a 98% you save roughly 28% of your fuel costs.
A few years ago I replaced my boiler and save nearly 40% on fuel costs and it is enough to pay for the cost over about 7 years. There may be rebates available or special financing so be sure to check it out.
I have a 2001 Burnham V8(oil burner hot water) with energy efficiency between 78-80%. Is that good for its age?
If your fuel bill is $1000/yr, an 80% efficient furnace would use $800 to heat your house and $200 would go out the exhaust.
If you bought a 98% efficient furnace, your fuel bill for the house would drop to $816, $800 to heat your house and $16 up the chimney.
FWIW, don't count on saving any money over the life of the furnace though. High-efficiency furnaces break down a lot as they age. Any fuel savings you accrue today will be eaten up with expensive repairs after the furnace is 10 years old or so.
A co-worker paid $260 to have a safety switch replaced on her high efficiency furnace last season. This year was another $610 for a draft inducer. In my opinion, high efficiency furnaces are poorly engineered junk.
98% wow
I just had my new one put in yesterday and it is 96% efficient
I expect that compared to the 80% furnace it replaced and the high Wisconsin heating bills it should pay for itself in well under 10 years.
As I pointed out before, the furnace will easily pay for itself in less than ten years. The research I did confirmed that it will probably last less than a "standard" furnace but 15 years is typical
Natural gas in the mountains?
yes.
98% ones are high maintenance item. I installed 96% one too, So far no problem since day one. Matching A/C unit has been running same. Last year I hat it checked for topping up the Puron but tech. told me, don't need to. He evacuated, weighed it and put it back.
Hi, IMO. this is too simplistic over statement. Of course old furnaces do not have inducer motor, but has safety switch. Maybe your coworker was not replacing filter regularly causing over heat.
I know more about oil than gas.
When I divide the output BTU's*** by the input BTU's on my 1979 Carreir oil furnace (hot air), I get about 80%. ***As listed in the owner's manual that came with the furnace, and is online too.
When I was shopping for a new furnace a couple years ago, the efficiency of all of them** was about 82%. (iirc but at any rate, little higher than my furnace rating.)
People here at the time did not believe me that the efficiency has gone up so little.
Are you somehow giving the measured efficiency or the rated one? Anyone know if there is an innate difference in the efficiency of hot air furnace vs. a hot water furnace?
** (except some special kind that is very expensive, not so often advertised or even mentioned, and very few buy (whose design name I forget. Retroactive, incandescent, self-descending, or something.).)
What is a hot water furnace? Most houses using hydronic heating have boilers.
Doesn't confuse me. Most "boilers" in residential heating don't come very close to boiling. But to answer the question, since they are producing 95% "efficient" boilers for residential use, I'd say they're probably more efficient since a circ pump probably uses less electricity than a blower. It's not a choice for most people if they like central A/C , because it's generally forced air heat that provides the vents for it. As far as I know new houses are overwhelming equipped with force air heat. My house was built in '59 or '60 and came with forced air. It was simple for me to add central A/C when I replaced the furnace.
If a boiler is being used, then flue gas is over 200 degrees. My forced air fan on 70k btu runs 300 watts or less. Maybe a bit more in air conditioning mode. It's variable speed.
Greg
On Tue, 27 Jan 2015 18:07:27 -0500, Curmudgeon wrote in
+1
In this thread, an oil-fueled device that heats water as does the " 2001 Burnham V8(oil burner hot water)" that thekmanrocks says he has
Sorry, I don't know what hydronic means and it's not a word the poster I was replying to used. .
Of course. I was just trying to figure out if there was a reason other than the choice of fuel, oil vs. gas, and the device used to burn it, that might account for his getting only 80% now. I didn't want to emphasize the 80% that my oil furnace is supposed to get heating air if a more recent oil burner would get higher than 82% efficiency when heating water. Although now I'm no longer sure the ratings include heating either air or water. They may ?? just include any heat that doesn't go up the chimney or other vent, and if there is some lack of efficiency transferring that heat either to the air or the water, that would be a) another problem, and b) one that manrocks can do nothing about unless he plans to remove the radiators and replace them with air ducts. (And that's only if hot air is more efficient than water, and not the other way around.)
Of course, both setups sort of lose heat in transmission to the rooms, but the heat is lost within the house, inside the walls or the utility shaft and isn't really lost at all, afaik. The warm walls or air outside the living space slow the cooling of the living space warm when the furnace is not running. .
What might be a good idea is to put heat reflectors behind the radiators. ??? When I slept right next to a steam radiator, either we had enough heat or no heat, so it wouldn't have helped.
Flue temps on high-effeciency boilers run 125-135F according to what I've read.
My first power vent natural gas furnace was purchased from Sears in 1982. It was made by Heil-Quaker in Tennessee, if I recall correctly. It used double wall steel vent pipe, vented horizontally thru basement wall and was supposedly around 90% efficient. In the 10 years I owned that furnace, every moving part on it was replaced at least once.
My second power vent furnace was a Thermo Pride that vented thru PVC. It lasted around 18 years and required lots of repairs in the last six years of its life as well.
I currently have a Goodman. It's been trouble-free so far but I expect the yearly break-downs to start soon.
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