It could range from relatively easy to complicated. Is there a crawl space or basement under the bathroom where you would have access to the ductwork?

I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.

Yeah I fixed one of these 3 story townhomes years ago, been back there a year ago to fix other HVAC company hackery. As this home owner is outside my primary service area so I charge extra to go there. More drive time = more money. Meaning the more work I have to do, I charge for it. These are extreme kind of jobs. Not many can solve these kinds of problems. A solution meaning: it doesn't create new problems. The solution works, regardless what kind of OAT you are dealing with. (OAT = outdoor ambient temperature) If you can imagine, how I went back there last year was that the guy they called couldn't fix it and recommended that the person that designed the HVAC zone system come back to fix it. (Me-- I hadn't been there in several years --- worked under all conditions --- hot, cold, mild etc. My climate needs air conditioning 9-10 months of the year.) In many cases the greater the load (temperature) the more problems there are to "deal" with. You lack "control" that is a design issue. You won't fix design issues trying to do what you're doing. You must change the design... or redesign the system. Where is the HVAC system located in your house? (which floor or is it in attic or basement?) I service the Katy, Texas area.

That duct is up high so I don't see it as a problem. Everyone has them. By having art over the fireplace you are drawing peoples' eyes away from the duct anyway. Was your house built in the '90's by any chance? The fireplace looks exactly like mine. :-) If your style is colonial the fireplace already fits that. What is it that you don't like about it? I am planning on removing my mantel and marble surround and replacing it with something less traditional, but if yours is a good fit for your house and style you don't need to change it. The only thing I would do is to spray paint the brass on the screen black. I don't think there is anything to be gained by moving the fireplace at all. That would be expensive. If you don't like modern you don't want to replace it with a linear fireplace.