Lay out

Sparkydsh

I'm finishing the second floor on my house, 500 sq feet. Do I need to lay out the radiators under the windows? Or can they be located on interior walls? The exterior walls will be very tricky to install. Boiler heat.

heatpro02920

more important than placement is

balance and sizing, heat loss calcs for each room and then degradation calcs for the heat loss to make up for the energy loss as the water moves down the loop.... Other than that just throw it up wherever you can, I always tell my customers, I'm not a magician, I can put the emitter / element where ever they want but the more invasive and time consuming the more it costs, plus when you start to need to build soffits and block in tubing that goes up walls customers would much rather have it where ever it is easiest.. I find baseboard is much less tricky than duct work and radiant panels... Truth of the matter is outside walls are usually the easiest place to add the board and make it a continuous loop not to mention fit the amount needed... Inside walls are much tougher normally...

TonyS

Your body radiates heat

to cold surfaces. The window having the lowest r value will be the coldest surface in the room. If you dont install the radiators under the windows to provide a warm air curtain, you will  be more likely to feel the effects of cold 70.

Remember, the more radiation you add, the lower the temperature water you can use but you must add it equally in each room.