Have you cheched the baseboard heaters for drain cocks. you may have air in the radiators. it is quite common. They will not heat properly or at all if there is air present.
My experience was, at the beginning of the heating season, I would bleed the rads of air.
Open the cock while using a small container to catch the water.
Open slowly, and be ready to quickly close. The thing will sputter and spit untill you get a full stream of water. Look out, the water may be quite dirty. so cover or protect carpets etc. The amount of water will be small, 1/2 cup or so.
You may have to do it again during the season. So keep checking.