If you are happy with it i would say run it til it dies.The only irreplaceable part on a standing pilot furnace is the heat exchanger.When that goes you will have to purchase a new one.

 

if your happy with at least 40% of the heat going out the chimney then stay with it.... I don't like heating the outside all that much....

 

I replaced my old furnace 3 years ago, from a 60% to the top of the line Trane. The old one still worked fine but I figured it was time, and I'd be proactive. Worried about losing it during a -40 spell. The installers were in and out in a day, and they did, well, an acceptable but far from great job.
The Trane has worked just fine, no problems, and I have no complaints. It seems far "smoother", and the house certainly feels more evenly heated, in space and over time. But was it worth it, $$ wise? Probably not. I could have bought a nice little boat instead.

 

we all have choices to make for the safety of ourself and family...most furnaces have a point where their failure rate is higher due to age.. which puts our safety at risk .. is your 45 yr old unit worth keeping... the choice is yours...we here at the diy site hope you make the right choice....ben sr

 

When we moved into our 108 year 2200 sq ft 3 floor colonial we had a company come in and swap the 37 yr old clunker that was originally plugging away in the basement for a York 97% efficient system. It actually had a faulty heat exchanger which is why it got scrapped. Our neighbor is paying over 30 % more than we are with his 25-plus yr old system in a house with a very similar layout and design to ours. Alot of the homes on our block were built by the same builder between 1895 and 1905 and are spitting images of each other.

The former owners of our home were paying more like 40% more with that nearly 40 year old antique. It is a pretty damn big difference. I would never trade a perfectly fine 45 year old furnace for a new high efficiency model just for the monthly savings. BUT... If I had a 45 yr old clunker that needed to go I would not put it off for fear that reliability issues with the new one would outweigh energy savings. If the heat exchanger had been OK we probably would have moved in and started socking money away for replacement further down the line. As it is I would expect this thing to pay for the extra cost over a lower efficiency unit in 10 or fewer years.

 

Nobody needs to or is here to convince anyone of anything as there is no profit motive in it for any of us. One day the heat exchanger may/will split wide open from metal fatigue and if you can get by with enough space heaters until the furnace gets replaced then feel free to do so. LOTS of people do that. If you are in a VERY cold climate like mine that is very unpleasant and not practical but lots of people don't seem to care or worry. As far as operating costs go, lots of my older clientele have nice pensions and steady cash flow and can afford to gamble etc so paying more for fuel is not a concern either. Depends on how you like to spend or not spend your $$ or whether safety is a major concern. Here are some pics of stress and metal fatigue failures and the old thicker furnaces fail the same way. They just don't rust thru as quickly.

 

My gas furnace is 45 years old, and works fine. In the 30 years I have owned it, I have had to replace the thermal coupler twice, nothing else.. The last time it was replaced was a couple of weeks ago, and the guy who fixed it said I should upgrade to a new 90% efficient furnace. I was all ready to do it until I stared reading about the new furnaces...all brands seem to have fairly poor reliability reviews. Most have some 30 parts that can fail, where as my current furnace has about 5 parts that can fail, and so far only the coupler has failed. That and the actual gas valve can be repaired by a service person (I don't DIY with gas) and anything else I can fix myself. I installed my own central air, with work with that furnace, so I know I can take care of anything but the gas part. There is so much with these new units that can go wrong. Another issue is with contractors I have called for an estimate. All four contractors have given me way different BTU requirement..from 40,000 to 70,000 and from my research, these high efficient units need to be properly sized or there will be problems. With contractors in mind, a lot of the reviews I read, say most furnace problems are caused by poor installations. I am getting the feeling I would just be buying myself trouble by putting in a new furnace. I don't care that my furnace is probably only 60% efficient. I will never live long enough to recover the cost of the furnaces I am being quoted on. Anyone care to convince me to get rid of the old, perfectly functioning furnace. Thanks for any and all comments.

ya you will always read bad reviews online. When something breaks people are quick to complain and give a bad review. But if something works perfectly it is easy to forget about it. In fact having stuff work so well that one can set it and forget it is really the goal of our industry

 

Thanks folks for all of the good replies. I have thought a lot about it, and I am thinking that a new furnace (from what I have read) has about as much of a chance to fail and my old furnace. It is NOT a clunker..doesn't sound like or look like one. -27C last night and we were warm as toast. HOWEVER, I still might go with a new one, so how do I determine what BTU is correct when four installers gave me four completely different numbers? I tried some of the on line calculators and got completely different numbers. Too small a unit is bad because it will cycle on and off supplying less heat, and wearing out parts, too big a until and it just wastes gas. (so I have read) Do I just replace it with the same BTUs stamped on my current furnace. It is a Clare Heckla (Clare Brothers) 85,500 in 68,400 out.
And one last question if you don't mind, I am looking at a Goodman GMVC95. Some of the online reviews were bad, some were good. In fact about 50/50. In looking at Lennox, Trane, Carrier, etc. they have about the same ratings, 50% good 50% bad, but the Goodman is less expensive, and the warranty is as good or better than the others. . Any "real world" experience from you fellows on Goodmans? Anything to look for in an installer?
Thank you so much for your time and information.

 

Some of the online reviews were bad, some were good. In fact about 50/50. In looking at Lennox, Trane, Carrier, etc. they have about the same ratings, 50% good 50% bad,

While online reviews can be a good source of info, there is something to keep in mind. almost everyone who has a bad experience will go on line to tell about it. Very few people go on line when they have a good experience.

 

you live in my climate and I will size it for you based on my 35 yrs experience. That Goodman model is very good and you need the 70,000 BTU model. the 45,000 is too small and the 90 is too big. being a 2 stage it will output 45,000 BTUs a lot of the time and get a true 2 stage thermostat to do that. the single stage tstat will use a timer to switch stages and that is not as good. as far as an installer check the BBB to make sure they have not had a lot of complaints or any outstanding and then ask your neighbors. friends if they know of a good company

 

Thank you very much yuri. While Winnipeg gets colder and more often than where I am, north of Toronto, ON, 70K BTUs seems to be what I would go with based on the current furnace, and my VERY limited knowledge. The house is only 1200 sq ft with a finished basement, double glazed windows, R60 or more in the ceiling. Walls have whatever the code was back in 69. In other words, probably not much. Still recommend the 70,000 BTUs?
Thanks again for your help.

 

I grew up in a VERY similar house built in 66 and about 1000 sq ft. 2x4 walls and vapor barrior was not done very well then. Dad being a smart guy figured that heat rises and insulated the heck out of the attic to R50 like you. Not Ukrainian are you?:laughing: Anyway I ripped out the glorious old Lennox Pulse I put in back in the early 80's 2 yrs ago and put in a basic 1 stage 70,000 BTU Goodman as the house will be sold in the near future. Wind chill is a HUGE issue for us unlike the South so I would go with a 70 and like I said it will run a LOT on low fire 45 so you get the best of both. I only use 45s in 900 sq ft houses or smaller.

 

Not Ukrainian are you?:laughing:

No, I don't think there is any Ukrainian in my background.:no: Thanks yuri...you (and the others) have been a great help. If I could, I would buy you all a beer (or a few) :thumbup:
It is too bad you are not closer, you would have the job if you wanted it.

 

A fair amount of what we do is not really economical, not so much about amortization or pay-back or saving on utility bills. Often it's not even about needed renovations/ repairs.

A lot has to do with plain peace of mind and personal comfort. I didn't NEED to change out my furnace, but at least I don't have to worry about it failing at a bad time now that I have. I bought some peace of mind. And I never hear my wife complain about her feet being cold anymore, so I also increased my personal comfort.

 

I am with you on this 100%

 

I'm guessing 90% of HVAC installs/replacements are really sloppy. Problem is, 99% of those folks don't know it. If your system is working fine and you don't think you'll see the payback, stick with it. You don't want to be coming back on this site in a month asking "why did they do this" or "I've got an issue with my new HVAC"!