Are you getting ANY heat? or none at all? Was it added to an existing run? You can only go so far with a single run, otherwise it will cool off too much. Did you bleed them to get the air out? Make sure there no valves turned off? make sure the pumps working....etc....there is a lot to check to verify everything is working properly first. What's your boiler Aquastat set at? what's your water temperature?