From my local h/vac guy: yes. to an extent. depending on the size of the room and type of radiant heat. Then there is the floor itself. Tile, marble types are better and hold the heat longer than wood or vinyl types.
Since hot air rises, there needs to be a way of circulation to distribute the warm around the zone.

I have read where they put the electrical type up to the floor and onto lower part of walls in larger areas (heat spreader plates?) - or install floor type radiators. In larger rooms this must be a given in the remote chance a wire kinks, or breaks, and the heat supply needs to be repaired. Always plan B as he says.

Also depends on how long you keep it running. For a large room it is not cost efficient.

Hope that helps. :)

Yes, hydronic radiant heat in the floor will heat the room. It is the most comfortable kind of heat there is.

I'm with hemera. It's not only the most comfortable but also the most economical. being that heat rises, it doesn't take as much to heat the entire room, so long as the heat that IS coming out of the floor is constant. As for the electrical mats, it is NOT meant to be a primary heat source, but rather just to heat the flooring (usually ceramic tile or stone) to make it comfortable to walk on. It WILL warm the room to a small extent, but will not work as a primary heat source.

When I redid our 80 sq ft bath (2 exterior walls) I removed the ineffective duct work and put in a Nuheat electric heated floor. The bathroom is on the 2nd floor, at the back end of our 40 foot long house as far from the furnace as possible, so there was very very little air coming from the vent as it was.

The room is very comfortable with just the heated floor all winter. I put a marble floor in and heat it to 85 degrees at different times of the day. Programmable thermostat is awesome.

Put the same floor in my basement bath as well, directly on the slab with marble on top (Ditra as well).

You'll be fine without your baseboards.

Yes, you absolutely can heat with hydronic radiant floor tubing. Our entire home is heated that way. We installed in ourselves and it was well within our DIY capabilities.

To different animals to consider, Hydronic radiant versus baseboard, in terms of the water temp they circulate.

With true hydronic radiant, you want to circulate water that is around 110-120 degrees. The goal is for the finished flooring surface to not exceed around 80-85 degrees.

The problem with converting baseboard to radiant hydronic is that baseboard systems typically circulate 180-degree water. Running water that hot through a tight hydronic floor system can result in thermal expansion and contraction issues with the floor.

For best performance, it usually results in having to put a the hydronic loop on it's own circuit separate from the the baseboard water. There are a few ways that can be accomplished.

You might be able to get away with circulating 180-degree water if you did something like a below-floor suspended PEX system in the joist bays. Not "staple up" with transfer plates, but simply suspending the loop a few inches below the subfloor. For 180-degree temps, I'd prefer to use copper over PEX. But that's a whole new thread in and of itself.

If the room is well insulated, or has no exterior walls, in-floor electric mats can provide enough BTUs to heat the room space. You'd need to consider the BTUs per sqft that those systems provide. An alternative would be in-floor electric for simple floor comfort warming, and something along the lines of a Runtal electric or hydronic Omnipanel for room heating. The Omnipanel can put out enough BTUs to heat a room.