To save money, re-do your duct work and keep the existing AC. You can replace it later. As for Radiant, I did a staple up in my ranch, and placed 1 1/2 inch foil faced foam boards underneath. I did not want to lift the current floors. It works OK, but If I were doing it again and pulling the floors, I would be more apt to a use a system that layers above the sub floor and under the finshed floor. Wirsbo makes a product like that. It has an aluminum backing too. Not sure if you can take the 5/8 to 3/4 hit in the ceiling height, however. In the bathroom, I would definitley use a sandwich layer, I did it in another house and absolutley love it. Floors are nice and warm. I warmed the shower floor and a bench too. Are you using engineered wood or hardwood? As for the crawlspace, is it a poured or dirt floor? Do water piped run through it. Handling the crawlspace is a whole other conversation. You need to do a heat loss study, than determine the pipe size and pump speed to keep the place warm. I just installed a system 2000 gas unit in my 1500sq-ft ranch with 1 radiant zone and one baseboard loop. It cost about 6k Installed (with indirect 40 gallon water heater) My next project will be an addition on a slab, with radiant in the slab.

Ross A dual fuel system can be a very effective strategy for heating one's home. Here are a few things that you should consider. 1. a complete understanding of nat gas rates and electric rates 2. your area's winter climate 3. your home's insulation qualities 4.a look into the future as far as whether electric rates are expected to be more stable than gas rates. In general, I have found that an electric rate of less than $0.11/KWh can make a high eff heat pump very compelling. I am attaching a fuel comparison calculator. Keep in mind that a heat pump performs double duty both in heating and cooling so its life may be marginally less on a dual fuel system depending on a good maintenance program. Today's heat pumps are much better as far as comfort than those 10 yrs+ ago. Good luck with your project and decision. IMO Here is a link that might be useful: Fuel Comparison Calculator

We have two Ducane heat pumps. They are three years old. The unit for upstairs has broken three times already. The repair guy who came today said it needs a new compressor. Needless to say, I am not a huge fan of Ducane.

christine1950- I'm including a link for applying bubble wrap to your windows for additional insulation in the winter, using nothing more than water from a spritz bottle, so it's easy to do and completely reversible. We've been using this tip during the winter for a number of years and getting great results. Our home is 7-years old and has energy efficient windows and we can still tell a difference - especially the bay window in the dining room when we sit down to eat. Tips about using this method.... -Cut your bubble wrap just slightly smaller than your window. If the bubble wrap is a little too generous and is larger than the glass, it will quickly get air under it and begin to pull away from the window. -Check your bubble wrap occasionally and spritz it with water again if it's pulling away from the window. -If you have hard water, use distilled water for the application. Hard water contains minerals that can actually etch your windows. -Bubble wrap with large bubbles works the best, but we have plenty of windows that have bubble wrap with small bubbles on it. -Check furniture stores for a free or cheap source for bubble wrap. -Grainlady Here is a link that might be useful: Bubble wrap window insulation