The indoor temperature is hovering around 20C on a regular day, I'd like to kick it up to 24C and not have to use electric radiators to supplement the heating.
In this apartment there are old soviet style radiators that look like this:
They are cast iron, burn your hand kind of hot, entirely non-adjustable and from the looks of it terribly inefficient at spreading the heat from the central heating system into the room.
This only has the potential to work because the central heating fluid going out of the radiator is basically just as hot as it is coming in. So I thought, why not extract more heat from it? I could increase the surface area of the radiators or add some airflow to get more!
For increasing the surface area, I did a test where I used aluminium tape. I cut 5x5cm squares and just stuck them to the radiator with around 1cm strip from one side connected to the radiator and the rest hanging in the air. So far I'm not super impressed, the heat does transfer but the part of the tape that's hanging in the air only feels warm and not piping hot like the radiator. Perhaps the tape is too thin to conduct a meaningful amount of heat before it disperses into the air. Perhaps the glue is inhibiting it too much.
By my calculations, I could likely use up the entire 50m roll of tape on one radiator and increase its surface area from the current ~2.5m2 to 5m2 but I'm not sure it would do much given the result of my small scale test.
For adding airflow, I pointed a typical 40w desk fan at minimum speed at a radiator and closed the door to the room. The room did go from 19C to 20C over the course of an hour or so. I'd consider that a success but I'm looking for more than a 1 degree difference.
In actuality, I would like it to be quiet and look decent so my plan is to put a sheet metal enclosure around the radiator and fill the bottom with around 8 120mm case fans running on 5v. By my calculation, that should give roughly the same airflow as my 40w desk fan did at minimum speed. I'm hoping the enclosure will increase the efficiency of the airflow.
I realize this is a bit fuzzy kind of a question but I was hoping that there is somebody here who has done a similar thing before. Are there better methods of getting more heat out of a radiator like this? Any tips for my current plans?
I've already taken some steps to even get to 20C. So far I put insulating plastic on both sides of all my windows, added insulating strips around all external doors and windows, moved furniture against external walls, added heat shielding behind all the radiators and sealed a bunch of little cracks around where the walls meet the floor and the ceiling.