Buy a direct-vent furnace if you have a place to put it where it can be vented directly out the side of the house with PVC pipe. A lagniappe could be that you will have much higher furnace efficiency.

Furnace is only a few years old, so replacing it is not an option really. Thanks.

The type of flue that you will need is very dependent on the type of furnace that you have. A new flue may require that you relocate the furnace. Existing ducting might, or might not need considerable reworking.

It might also be very difficult to locate a new flue within the walls of the home so you might have to ask yourself if you want a "pipe" running up the outside of your home to over the roof level.

"so replacing it is not an option really."

Replacing it is a very viable option. It just may not be one you prefer.

What's truly not an option is removing the chimney used by the furnace unless you replace it with something else. Replacing the furnace with one that doesn't need an exhaust stack may indeed be the cheaper and easier way to go, furnaces aren't all that expensive.

What flavor of furnace are we discussing here, nat gas, fuel oil,....

Yes, SnidleyWhiplash put it well. The question is how important is it to remove the fireplace and how much do you want to spend. The least expensive route may be a condensing furnace with a PVC vent. Even a PVC pipe out the side of a house can be difficult to place sometimes (sidewalks, patios decks and aesthetic issues get in the way all too easily) so that might not even be the solution.

Ok - I see what you mean now, sorry! It is an oil powered hot water baseboard system. On the outside wall 15 ft away there is a gas fireplace with a flue/chimney on the exterior - I was wondering if the existing furnace could be redirected along the basement ceiling to vent out of the gas chimney? Or does it need to vent straight up? Thank you all for your patience.

Ah, OK, so its an oil-fired boiler.......... BIG difference!

Oh, that is a horse of a different color. I know that, colloquially, boilers are often called furnaces in some parts of the country. Try to call yours a boiler or some people might be confused. Furnaces make hot air, boilers make hot water.

You have natural gas and someone recently installed an oil boiler? I am glad that I don't have to dance around the issue that that is was a a decision that is pretty impossible to understand. It was not your decision so I can tell you that without really unusual circumstances, it was a really dumb decision.

You can't leave the chimney in place and make it a feature in your new floor plan?

I know that direct vent, higher efficiency fuel oil boilers exist, but I don't know much about them. If your boiler is direct vent, it is likely that you can redirect the flue gas out the side of your house. I have a feeling that you might not like it because there might be fuel oil smell, but please check that out with other sources if yours really is direct vent. It is very likely that you can not redirect the flue gas up a masonry chimney that is partially exposed like the one on the side of your house if it is a condensing boiler. If it is not a condensing boiler, you might be able to use that chimney, but I bet you will have to move the boiler to the base of that chimney. Again, don't take that as fact because I am not that expert. You must be very careful of changing the use of chimneys. By changing the type of fuel burned and the efficiency of the appliance, you can dramatically change the amount of moisture and the acidity of the flue gas. That can destroy the chimney if it is not lined properly of the application. High efficiency, condensing boilers, furnaces and water heaters produce a lot of low temperature, moister flue gas.

What I do know is that right now natural gas is so much less expensive than fuel oil that you could get a pretty fast return on your gas furnace conversion. There are lots of state-sponsored programs that offer funds or no interest loans to pay for such conversions. Some of them limit the repayment rate to the difference between what you are and would have been paying for fuel so you are really never out any ready cash. Unfortunately, adapting a new, high efficiency boiler to an older design hydronic heating system can be complicated. Sometimes it is not and it is never impossible so don't be discouraged by that. You just need a contractor that is competent and conscientious.

To mover forward, please:

1) post the make and model of your boiler

2) read up on condensing boilers and the difference between them and old-fashioned boilers

3) check on energy efficiency programs in your area including what kind of energy evaluations that they offer

4) read up a little on chimney types and how they are lined.

5) tell us if your domestic hot water is produced by this boiler or a separate water heater.

We don't have natural gas - there's a propane tank for the fireplace! Clearly, I am a novice. Our old house had forced hot air and "furnace" so I guess I didn't understand the difference. I will do as was suggested @ionized_gw and be back. Thank you.

Not a horse of a different color - it's a zebra. There's no horse there at all.

A good HVAC contractor can look at the physical layout, assess the situation and give you alternatives. This little wild goose chase well demonstrates the difficulty of getting advice from a distance. From fellow homeowners, not from experts.

Thank you. I was just trying to get a little knowledge to see if it was even possible before I contacted a professional. I am sorry if I frustrated you all.

No problem at all. Feel free to post away anytime you think it could be helpful for you.

czp22, not at all. People of all levels of understanding post questions here. Some posters are frustrating for other reasons, but frustration usually does not come from people that are sincerely trying to learn.

Agreed, there's nothing wrong with being frustrated. HVAC issues in a home are an expensive black hole for everyone, it's maybe one of the worst things to have to deal with. It's an industry seemingly full of only saints and sinners with nothing in-between and with no way to really know in advance who is which.

@Stoveguyy - I was thinking the same thing... I blame Fixer Upper for making it all look so easy. How in the world do they do all that and stay within those budgets?!!! Yes, we thought of all those expensive things you listed. We are trying to figure out how to keep the family room fireplace and still have an open floor plan. Sadly, it is a big obstacle right in the middle - backs up to and blocks access to a unused living room that 28 x 15. Thank you for your thoughts.

hows that's for an ugly corner fireplace? Hard to see? That's our family room/storage room. since we can't use corner, we use it for storage. Yes, we have 5 fake Xmas trees.

@stoveguyy Boy, that IS very unusual - too bad it wasn't angled.

Angling it would not make corner any more useable. It's metal. Zero clearance? Flue runs thru 2nd floor closet above. Wife thinks it adds value to house so it cannot be removed. I tore out a similar age unit in lower level and replaced it with a gas unit. About 200 hrs of wasted time. Looks good though. Wish I hadn't reused the original masonry bump out on rear. Talk about air leaks.going to redo it all. That's our LL storage area.