Does a floor heating register have to be under a window?

grantiman

Have a new built with a 4x8 Andersen window in my living room, my heating diagram called for 2 floor registers under the window. I have a floor joist running about 4 inches out along my foundation and can't get my registers close to the wall under the window. Can I put these 2 registers on an inside wall close to the window, see diagram below. I wasn't sure by putting these register on the inside wall if my window would get condensation seeing it's on a cold west wall.

Jamie Hall

Even with registers right under the window, condensation may be a problem. Spacing them out into the room isn't going to make much difference; most registers have some diffusion or spreading capability anyway.

hot_rod

Or header out that joist in the two window vent locations. A not so unusual task for the framers.

EBEBRATT-Ed

Use a long linear floor register and mount it as close to the window as possible. I would not put them on the inside wall. You want the long register to span as much of the window as possible

exqheat

Heat sinks to the window from the room air. It makes little difference where radiators are as long as you do not need to heat cold air coming through an open window. During the flu epidemic, radiators were recommended under windows because fresh air was required to reduce flue epidemic ( true or false, that's what they did) . Today most heat is in baseboard radiant panels that come from the floor along the outside wall. (no relation to window location.

Kaos

Lot of it depends on exactly what windows are you getting and how cold your climate is. With low E windows and i89 coating, there is much less heat loss at the windows, so you can put the registers further away. If you are somewhere very cold and those are not triple pane windows, I would try to get the registers there.

Even with 4" space there are ways to get ducting there (ie, run the duct under the joist and a longer boot to get up to the subfloor) if not, there is nothing really all that wrong with having the register a bit away from the windows.

Condensation generally happens from indoor humidity that is too high, getting heat on the windows does reduce at a bit but doesn't stop the condensation in the rest of your walls.

https://nrc-publications.canada.ca/eng/view/ft/?id=5b01cc78-a2b5-4be4-be5b-f681e8b741bf

hot_rod

the windows, regardless of the quality are the lowest R value in the wall assembly

With the heat emitter under the window the movement of the heat will minimize the cold temperature of the glass as you stand or sit in front of it

Any furniture planned for in front of the glass?

EBEBRATT-Ed

Your supposed to locate the heat emitters where the greatest heat loss is. Windows loose more heat than walls

PRR

Can I put these 2 registers on an inside wall

This works OK. New construction in Maine, 2011-era standard of insulation, good new window and door nothing special. It is a little cooler sitting by the wall but few degree, not brutal. One register blows the full 12 feet across the room, the other only 9 feet but through a deflector.

EdTheHeaterMan

@grantiman, installing register boots is not rocket surgery! You dont need the register boot against the wall, it can be 8" out from the wall and still do a good job. With the floor joist shown on your diagram, the space between the first and second joist will work fine if you do not have space between the box plate and the first joist.

Or you ca nget extra long boots and use 2-1/4" x 14" boots and registers. A good sheetmetal man can make anything work.