Floor register? - Radiator heat in a 1919 bungalow

[merula]

I live in a bungalow in Minnesota that was built in 1919. The current heating system is baseboard hot water radiators, probably installed in the 70s or 80s; the original heating system was either a hot water boiler or gravity-fed heat from the basement, not sure.

We have a number of problems with heat distribution through the house:

• Kitchen is almost always hotter than the rest of the house, summer or winter. It's directly above the boiler, northeast side of the house, and has a very small entry. My suspicion is that the small doorway keeps the heat in year-round, and in winter the kitchen is heated twice-over (from its actual radiators and the radiant heat from the boiler). Solution might be to enlarge the doorway to promote air flow and possibly turn off the radiator.
• Converted attic bedroom is hot in the summer, cold in the winter. We run an exhaust fan out the window furthest from the stairs, which seems to help, but not entirely mitigate the problem. (For example, if the main floor was 80F, the upstairs with the fan is 85-90F and without the fan is 90-95F.) There are radiators upstairs and some sort of vent that was covered over when we bought it. The only window that fits a window AC unit is right at the top of the stairs, so when we've tried that all the cold air goes down the stairs and it doesn't actually help the rest of the room. I think for cooling the only real solution is a portable or permanent non-window AC unit, but for heating I'm not sure what the issue is. Should we open the vent?
• Basement is super humid in the summer. A new dehumidifier runs at least 12 hours a day to keep it at 60% humidity. It's also typically 10-20 degrees (F) cooler than the rest of the house, but that's not normally an issue. (It's nice in the summer and bundle-under-blankets cozy in the winter.

Recently, pulling up some laminate flooring in the hallway revealed a hole in the original hardwood approximately 8" x 20", which looks like it was for a gravity-fed heat vent. There's also a wood floor patch in one of the bedrooms that could have been a heat vent; before this I assumed it was under a cast-iron radiator and there was water damage or something. It's right under a window.

Would it be helpful to replace either of these floor patches with a vent?

[Sibley]

Hi 1919 house buddy! Mine was converted to forced air at some point, no idea what original heat source was.

Kitchen: My first thought is that you should investigate turning off the heat just in there and see what impact that has. If you can, you may get enough heat from the boiler/oven to be adequate. You do need to be careful not to disturb the overall function/flow of the system though, as that could damage the boiler or introduce other temperature variations.

Attic: um, it's an attic. Hot in summer, cold in winter. This is a universal truth. Hot air rises. A portable A/C unit will help in the summer. What's the temperature in winter? Heat the people, not the space. Blankets, small space heater, better clothing. We had thousands of years before central heat, look to that for ideas. Make sure your insulation is up to snuff as well.

Basement: The humidity and cooler temp is typical. They're at least partially below ground after all. A dehumidifier is a good idea, though 60% seems too high to me. You're going to encourage mold/mildew with that level. Do you need a larger one, or to have that one run longer? Additional airflow in the basement itself may also help. This should subside in winter.

I would not reopen old vents. You don't know what you might be getting into there. The problem with pulling air from basements/wall cavities into living spaces can be serious. Particularly if you're pulling additional humidity into the main house you could end up with moisture problems.