Living Room Radiators not HOT as others

ImYoungxD

I have two rads (painted beige) on the 2nd floor that gets really hot that the room gets too toasty that a fan has to be on to blow it to the hallway.

2 rads (not painted) on the 1st floor gets heated up but not as hot as the 2nd floor.
Thermostat is on the living room. One zone
Heating is fine to satisfy the thermostat temp.
All rads use hoffman 40
Main vent is BM
No short cycling and 1 degree setback
No covers
No hammer noise

Could the beige paint be radiating more heat than unpainted?
Could insulation be the cause? 2nd floor is well insulated while 1st floor is poor (solid walls).

Gsmith

Sounds like typical unbalanced venting of the rads. If you are sure the steam main is adequately vented, and it sounds like if there are only 4 radiators in this house and you have a Big Mouth, then I think the easiest and least expensive solution is to buy two Ventrite #1 adjustable radiator vents and put them on the upstairs (hot) radiators and then slow down the venting so they don't heat so hot. With the adjustable vents you can dial in the comfort for each. Slow down the upstairs will let the downstairs heat up more, and less heat upstairs. And don't forget if you have an open stairwell some downstairs heat normally flows up to the second floor through that lowering the need for heat upstairs.

Gsmith

Oh, and to your question, paint does have a small affect on radiator output. Search this site for the article on radiator paint. But the general rule is most non-metallic paints have little effect on the rad output, but metallic paints, (silver, gold,) reduce the output maybe 25-30%. I'd use the adjustable vents instead of changing the paint, easier and cheaper.

ImYoungxD

Thanks Gary. I will look into the vents.
The stairway is blocked off with a thick curtain.