I would second the motion on a mini split heat pump, because the actual workhorse sits outdoors on the ground and the condenser mounts high near the ceiling. I installed a Fujitsu model a few years back in my kitchen/dining room. You could barely hear it run. the air dehumidifies and cools in summer, and reverses action to heat in winter. It will sweep the heat flow or fix it across the room or down to the floor. The unit is a very efficient. As an alternate heat choice without the summer cooling option, you might have a local gas company size the room to see if a Rinnai gas space heater would fit below one of the windows.

I called Craig (?) at Turbonics directly and he couldn't have been more helpful (the woman who had answered the phone was quite nice and helpful if I recall, as well). Looking for kick heaters drew me to GW, too, and I'm still here 5 years post-reno!!! We lost an entire section of hot water baseboard heat in our kitchen when we installed cabs along an outside wall, and the remaining "return" segment of wall adj to it as well. Craig helped me figure out how many BTU's were required to replace the am't of heat "capacity/output" we were losing, and which units we needed in order to achieve that. He gave us detailed instructions for our plumber (who up until he installed our kick heaters, disliked kick heaters--he was very impressed with the Turbonics heaters when he tested ours on install). Craig told us where to install them for maximum benefit, how to install them using the supplied switches, etc. I got the name of the area rep from Turbonics (either on their site or over the phone, who then told me where I could purchase the kick heaters locally (plumbing supply house not too far from us). We turn ours on/off using the switches as needed (don't need them running when we won't be in the room for a while or out for the day). The fans do a good job pushing the warm air out into the room. On less chilly days, the radiant heat (emanating from the pipes) is usually sufficient. Good luck!

I have two Turbonics 6/8 Toesters in my kitchen tied to my hydronic heating system. They are sufficient to heat the entire kitchen and former LR space, albeit slowly if one demands a large change in temperature. I know this because pending the last coat of floor finish, the LR is still missing its baseboard heaters. This heating performance is in spite of the Toesters being operated at lower than low speed. Fan speed is deliberately turned down because I found that the fans would start "breathing" when the access panels in the floors of the cabinets were closed. (Turned down means using a motor controller in series with them and wiring them for low speed.) Although the 4-inch kick space meets the requirements of the heaters' drawings, I suspect that there is too much restriction above the fan for the fan to operate stably. I didn't care for the sound, even though it was subtle. Smaller units may not have this issue with this height. kas A motor controller or fan controller is like a lamp-dimming wall switch, except a CW action lowers the fan power rather than increasing it as in a lamp dimmer. They are also tolerant of inductive loads. Most electrical distributors should carry them.

Thank you everyone. I really do appreciate--and take to heart--the advice to just replace the door. It's clearly wise counsel and I'm currently looking for doors. But I also think the heart of the original question is being lost in the door-replacing zeal. Even if I do replace the door, I still need to find a way to heat that part of the kitchen. That door is on the kitchen's exposed wall, so whatever form of heat I ultimately place in the kitchen ought to be near that door and that wall. Right now I am just trying to find the most energy-efficient form of electric heat for the kitchen in that spot. So, all things being equal (and assuming I get a nice new heat-tight door), what's the most thermodynamically efficient approach for that spot--toe kick, floor insert convection fan, or caddy-corner baseboard? Thank you very much.