Does the hall bath have a window? Outside wall? That will make a difference in how hard it will be to keep warm.

We intalled undertile heat in our kitchen and family room. The brand we selected was Warmup - as I recall their wire gets warmer than most brands and is actually rated for use as a sole heat source.

the heater cable is the same in any case.
In toasters, do manufacturers claim their heating cable is better? No.

To know if it's too much or not enough is not a big concern.
You let the thermostat do the work.
Don't undersize it.

there are many threads about this topic.
One is currently on page 1 or 2, today.
Hope this helps

First of all, yes, there is a rather large window on an exterior wall which will be replaced as will the insulation.

As for the threads on this topic, I really, really searched them and just ended up more confused. I guess I was just hoping for a yes or no answer.

Thanks.

I would think so assuming that the insulation is sufficient and the radiant floor warming system covers the entire room.

However radiant floor heating will not suffice if you want a room to be heated up really quickly (ie - under 3 minutes).

I think davidrol is wrong about all floor heat brands being the same. As I recall, some have a PVC coating, others have teflon coating. They also differ as the Electromagnetic field generated (EMF). And the wattage varies (12 for Nuheat, 15 for Warmup). Warmup heats to 131 degrees, Nuheat says 90 degrees. When I was shopping for floor heat, I did online research, then talked to the reps for the brands I was considering and asked "why should I buy your brand?".

If you are replacing your window and insulation, that will certainly help. In addition to the floor heat, you could also get an exhaust fan with a built in heater - Panasonic makes one that seems to get good reviews.

legalsec111 everybody with heated floors is happy with the floor, unless the heat is too weak. (Several causes for this).

the physical transformation of electric power into heat is the same in all cables, but no manufacturer will admit that outright; instead they will find diversions to talk about.

If your not replacing your exhaust fan, Hunter makes a fixture called illumiheat. I used it in previous remodel. It looks like a ceiling mounted pendant but also has a heater in it. Loved it. We didn't want to deal with changing the vent/fan out and cutting a bigger hole, blah blah blah. I found illumiheat and loved it.

No - I do not believe that radiant floor heat alone will come even close to providing the heat you get from an old radiator.

Your best bet is to simply call the company that services your furnace and have them send someone over to give you an estimate. They will be able to tell you how much heat you get now based on the number of ribs on the current radiator, and then give you options on replacing that heat.

There are all kinds of new low-profile radiators on the market now that can take the place of the bigger ones.

I refinished and kept the original radiator in the bathroom we just refinished and I am very glad I did.

We have hot water baseboard heat throughout our house. MB baseboard remained same size with our reno, the hall bathroom's is now shorter than it was. We don't have Whisper Warms, just the Whisper fans w/out heat. Both bathrooms have Nu-Heat floor heat mats under the tile.

We definitely need the baseboards in addition to the floor heat, esp in the MB, which is over the garage. It's possible setting the thermostat for the floor heat to ambient, rather than floor would help to heat up the room more, but we didn't want to try that.

You will always need "real heat" to heat the room, even with radiant floor heat. Electric floor heat is only intended to heat the floor not the room. And how well it does that job will vary due to room location, insulation installed, radiant barriers present, and wattage and spacing of the wires. Installed correctly, your floor isn't so much "Toasty warm" as it is "not cold". It doesn't take a lot of heat to raise ceramic from ambient room temperature to a temperature that feet will consider as warm, even though an actual objective themometer reading may only say 85.

The biggest drawback with radiant floor heat (either hydronic or electric) is the lag time in response from you changing the thermostat or turning it on or off. It takes a couple of hours for some thermal masses to come up to temperature. I you are installing it on a slab that isn't insulated, you will never get it to be as warm as it could be in other installs because it's fighting a losing battle with the heat lost to the ground and exterior. The quickest response will be in a second floor bath install over heated space below with a thermal barrier and insulation installed underneath the floor.