LP gas and radiant electric heat are typically among the more expensive alternatives. Make sure they're the right choices for you before investing in a new system(s) and getting an unpleasant surprise when you get your utility bills. To that end, I suggest you begin by having an energy consultant visit your home to help you understand the costs (both initial and ongoing operating costs) and feasibility of various alternatives.

Radiant electric wires is a floor warming system that adds a luxury comfort experience to the barefoot user. It adds a mild amount of heat to the overall home heating. It is not a substitute for the central heating systems used to heat the home as a whole. If you want a boiler and under floor tubing to radiant heat the home, that is a MUCH more invasive and expensive project.

Runtal offers both baseboard-type and panel-type electric radiant heaters https://runtalnorthamerica.com/residential-electric/ They may be the least (initial ) cost alternative for retrofitting an existing home, but they are likely to be the most expensive on an operating cost basis.

If you have propane, and are putting in forced air, why the need at all for a minor semi duplicate function? If you say for a luxury, that's a valid reason. But the cost will be a lot higher than a pair of mukluk slippers.

To help your project with the most efficient use of the of a radiant heating system it's important to install a radiant barrier on the opposite side of the heating system to reflect the inferred radiation back to the direction you want to heat. The effects of radiant heat is produced by the radiant heat source emitting very long inferred electromagnetic wavelengths of energy, and deflecting them in the direction you which to heat, this will increase it's efficiency to get the most from your radiant heating system.

It's also important to insulate the back side of the radiant system to also increase the efficiency along with picking the best conductive material to transfer the heat above. When selecting a contractor make sure they are including a radiant barrier and insulation on the underside of the floor or a lot of your heat will radiate down.

Radiant heat electromagnetic waves will travel in all directions, so because of this favorable principle radiant heaters can be placed in any plane. They can be located in the walls and ceiling to produce the same benefits as in the floor, this is an option few do because few know about it. The same requirements are still required with insulation and a radiant reflective barrier but it is an option.

The best place to use this option is in the basement of a 1905 house, or any house without insulation under the concrete slab. Putting a radiant floor heating system in the floor of a slab with no insulation is the quickest way to go broke paying the utility bills.

Years ago I saw these high velocity ducted systems being installed in old houses by the show This Old House (Bob Villa). Worth considering for an old house with limited space for ducts.

https://unicosystem.com/

https://www.bobvila.com/articles/choosing-a-high-velocity-hvac-system/

“All together, I figure it will add about 10K to the bath job.“

Now imagine people doing electric snowmelt of large driveways & stairways.

IMPO

SR