Yes, it is a simple swab of forced air gas heaters. Did I say we have a twinned(?) system? We have to replace two. It’s about $8K per piece. To repair would cost less than $3K. High efficiency unit wasn’t that much more expensive but it’s tough to vent out sideways. Although the unit is old, many parts have been replaced over the years. Would it last if I just replace the heat exchanger? What else could go wrong?
replace …the 20th century is calling and asking for it’s heater back
Replace heat exchanger alone re post 35,
If the motor is new, and the rest of the heater is still ok per your inspector, I would go for the replacement of the heat exchanger.
I replaced two furnaces for $8400. One was enormous and the other pretty darned big. I’d get more estimates. I got three and they differed by many thousands.
Absolutely second that. It pays off to shop around for big ticket items like that.
Yes, shop around and replace. Last year I replaced the furnace in a rental house, and after a lot of information gathering, ended up with a two stage furnace. Supposedly far better for comfort, as rather than blasting on, and then off again, the lower stage runs more consistently, keeping the place warmer, and saving on energy bills. Two stage, being more efficient had a rebate associated with it in my state, Wisconsin. Cost does depend on size of house, and thus size of furnace.
My own house has a boiler, and I did replace it probably 20 or so years ago after the boiler cracked on the old one. . I love my steam heat, as it is far better for allergy sufferers, and keeps my towels toasty after showers. The best thing about the new one is the auto fill system.
Regarding cost and size of furnace, there are many sizes and variables, based on climate, insulation in the house, and square footage to be heated. Get several bids, and a feeling for costs in your area and for your particular situation.
I am getting two more estimates on Monday. Repairing it for less than $3K sounds attractive at the moment. It’s a lot less money and everything will remain the same.
IN NJ I got a deal where I replaced my ac/heating system and hot water heater plus insulated the attic at R50. They put in a very high efficiency unit.
It costs $10,000 to be paid back over 10 years zero interest.
I never check to see if my bills are less but the house is much more comfortable. The temp stays very steady compared to how the old system worked.
I recently put in a new high efficiency gas forced air heating system. It does not vent through the chimney - instead it vents directly outside through a PVC pipe. (they had to seal up the connection from the old one to the chimney and cut a new hole to outside.) Besides being energy efficient (I am saving money on fuel bills), it has a different fan system so that it has two speeds and ramps up to keep the house at a more even temperature (needed a new thermostat which communicates with the heater to do this). I think the system was a great investment (don’t remember how much it cost)
The quote I got for the high efficiency was about $8,500, just a little higher than the standard one. For us, it will be hard to vent to the side of the house, two PVC pipes sticking up 18" above the ground.
When it was first completed I was not thrilled with the pipe sticking out from under my front window (through my concrete basement walls) - I don’t even notice it now and it has not proved to be any problem (even when seemingly ice-covered in the winter).
You are describing MY house, not Iglooo’s.
And the cost of the forced hot air system would be $25K or more, IIRC. The duct work for the first floor would run around the cellar. The only practical way to get ducts up to the second floor would be to box them in in the corners of rooms on the first floor. We would probably forgo that and do some kind of auxiliary heat in the bathroom. We like cool bedrooms, and we have two staircases up which heat rises, and the second floor is heated by the sun in the winter also.
I believe if we went that way we would not vent through the chimney, so it wouldn’t have to be relined. If it were relined, for a replacement gas burner/boiler–the $17K solution-- they use stainless pipe, not ceramic.
We decided to put in a new hot water heater, so that we could turn off the behemoth furnace during the non-heating months, which for us is about April to the end of October. We’re sticking with the behemoth until it dies, or we win the lottery. If I win the lottery, I’m going with geothermal. 
We got a new gas boiler last year (Lochinvar Knight) replacing one that was only about 20 years old (forced hot water system). The new ones are far more efficient than the old ones (they are 95-96% efficient). There is very little loss of heat - almost all is recovered. The emission is so cool the steam from combustion condenses as water. (We did not need to replace the radiators or pipes, just the boiler. We also kept our indirect hot water tank.)
They can vent it up through your existing chimney. This is what ours does.
I’m talking about residential gas furnaces which supply hot air. They are among the simplest and most basic of heating appliances. I was also quite clear that the costs I quoted were without profit and “labor” because I am never quite sure what inflated amounts uninformed consumers are willing to pay to have heat in their home. I know it is quite substantial, however.
For example, people will pay huge premiums for brand names. Because these units are so simple, many are made in the same factory and then sold for 2X, 3X or even 4X more with the addition of various brand names.
While there are heating systems that might be termed “mini-duct”, you may be referring to a “ductless mini-split” which is a heat pump system providing both heat and A/C. They are among the most efficient and cost-effective forms of providing residential heating and cooling.
Perhaps heat pumps are “most” cost-effective in some climes, but certainly not all.
Given the large variety of climates and situations found in the USofA, it would be appropriate to be skeptical of someone who said that they had the one answer for everyone. However, note that I clearly said “among the most”.
Heat pumps only work in certain climates, they don’t work well in places with very cold climates, they can’t make up the differential in temperature in many climates. More importantly, while heat pumps are efficient (they are basically a ‘reversed’ air conditioner, same principle in reverse, they use the heat generated when the gas is compressed to heat, rather than cool when the gas expands), they are also electric, and in many places electricity is not cheap, natural gas would be a lot cheaper.
@justonedad:
Yes, gas furnaces are relatively simple units (hot air I am talking about), I took a gander Home Depot website and there were small units that cost less than a thousand bucks, as you said, though the capacity on them tended to be pretty small, like in the 50-70k btu input range. However, a furnace is not something most people are going to install themselves, it isn’t a simple DIY project and there are consequences for not installing it right. A hot water heater in many cases is ridiculously easy (with flex gas lines and water lines, a 10 minute install), but a furnace is difficult, if you get the venting wrong, if you don’t fire it up right, you can end up with big consequences, and if you install it without permits or getting the gas company to sign off on it, and something happens to your house, the insurance company can use that to deny paying off on the house. It is kind of like telling someone replacing an engine in a car is cheap, yep,for many cars you can get a cheap rebuilt engine for a fraction of what a mechanic would charge, but few people have the skills to install it either, so the real cost involves installation and the like. It is much like whole house generators, the generators themselves can be relatively cheap, but installation doubles the cost, with permits and so forth.
Not sure who you are addressing, since the OP doesn’t need to replace their whole system, and has gas already.
If you were talking to me, no, they cannot vent a GAS furnace up through our existing chimney without lining it, which would cost about $3K (height of the cellar plus two high-ceilinged floors plus an even higher hipped roof). As both Musicprnt and I explained, the exhaust produced by a gas burner is different from that produced by an oil burner, and it will eat away at the portland cement between the bricks causing the chimney to leak and eventually collapse.
Things can be a lot more complicated in an old house.