Hi. I am not an expert on this and I'm sure you'll get more feedback. However, just last night I took a class on bathroom renovation. The instructor, a longtime owner of a kitchen and bath store, said that radiant heat under tile floors is only good for one thing -- warming your feet. It will not heat the room.

Your idea of a wall heater would probably do the job, but a heated floor will not.

I absolutely find that radiant heat in the floors, under tile, will heat the room. I have it in one bathroom, the kitchen and a 30 x 20 recreation room.

It's not the most efficient heat (electric) but it can heat the bath unless it's extremely cold. If you need expert advice, check with an installer who knows how to do heat load calculations.

Radiant heated floors do warm the room a bit (when I'm in the bathroom with the door shut while getting ready while DH is sleeping, the room is noticeably warmer than the bedroom when I open the door again). I think the biggest heat gain, though, is probably that if your tootsies are warm your whole body feels warmer. So even if the ambient temperature isn't much different, your personal warmth satisfaction quotient will be higher.

I read the op as asking about supplemental heat in a bathroom that sometimes doesn't get warm enough. I think a 5 x 5 electric mat under tile would be much nicer than a wall heater. Warm tile is heaven on a cold morning.

Our MB is heated only by electric heat under the tile. It does a fabulous job. The bathroom is warmer than the bedroom when we get up. The whole room is 10 x 10, but there is no heat under the 3 x 4 shower or the 2 x 4 vanity. We did put it under the clawfoot tub because we wanted the heat for more than just walking on. It's not very fast. Depending on how cold it is, it takes 1-2 hours to make the whole room toasty. The heat is on a timer that turns it up for morning and evening and down the rest of the day. The warm floor is my favorite thing about the whole bath.

I am assuming that you have some other type of "regular" heat in your bathroom, and you just want to make it toasty in the mornings. Other people seem to be pleased with the Panasonic Whisper Warm fan. I thought it would look ugly up on the ceiling, but a white fan with a white ceiling blends in pretty well, and I don't really notice it. Mine is not yet hooked up, so I can't tell you how it works, but I did get the idea from this forum, and other people have raved about it. It does warm up the room quickly. But, it won't warm your toes like radiant will.

When we finished our basement we squeezed in a full bath. It is internal, with no exterior walls and there simply wasn't room to run heat to it. We opted for heated floors (yummy!!) and the Panasonic Whisper Warm. The travertine and heated mat is layed on top of concrete slab. The floor space is smaller than your 5X5. There is never a difference in temperature between the bathroom and the rest of the space downstairs. It's worked out beautifully and we rarely use the Panasonic heater.
HTH!

I think most people with radiant heat are really glad they installed it. I know we really are glad we installed it in our master bath, and it's our only source of heat in there.

It's hard to know exactly how it will warm your space, because it depends on a number of factors, mostly where the space is located in your house -- for example, is it on the second floor above living space (ours is directly over our living room), or over an unheated space like a garage? Also, do you have another source of heating in the bath? We do not, but it is surrounded by rooms that do have other sources of heat, so it is not isolated in that way.

Our master bath is not huge -- the total is about 7 feet by 11 feet, tops. One big reason it is so comfortable is that our system, Warmly Yours, has a thermostat, like most of them do, and you can set the temperature for different times/periods of the day. We make ours get hotter an hour or so before we wake, and then go back to about 72 degrees the rest of the day. I don't remember the exact temperatures, but my point is, in the winter time (we've only had it since the winter began), the system is never really off, radiating a low amount of heat all day, so the bath is never really cold when you walk in, neither the floor nor the space.

I think it's also supposed to be relatively inexpensive compared to other kinds of heating, but I'm no expert and I certainly have done no scientific tests on it.

Anyway, my point is the bath is real comfortable, and we ar e so glad each and every day that we installed radiant heating.

What weedyacres said is right to the point, "if your tootsies are warm your whole body feels warmer" the radiant floor heating not meant to heat the room, in some cases it will.

Take my advice... install baseboard heat! My newly renovated bath is 5 x 7 excluding the tub/shower and, like you, I had to decide whether to install baseboard heat. Because I installed radiant heat (which I love) and straightened a crimp in the duct leading to the bathroom register I gambled that would be enough. I leave it on all day and it isn't even closeto getting the room as warm as I'd like. My bathroom is over a crawl space. Consequently I'm back to having a portable heater.

We recently created a 4 x 10.5' bathroom. There is a 4 x 3 shower at the end of it, so the usuable floor space is 4' x 7'.

We had a standard vanity, and went with a toekick heater, and electrical radiant heat. I didn't want to use up valuable space on a baseboard. However, since you said you were putting in a floating vanity, I would suggest an in-wall heater (they can work via your heating system), in conjunction with radiant heat. I'm so glad we got the radiant heat. It makes a world of difference. Depending on how cold your climate is, and where the bathroom is located will help you make your decision. I was quite sure that radiant heat would not be enough in a northern climate, as two of the shower walls were on outside walls, or cold walls.