Why is my radiator making the noise of running water, despite the heating being off and the radiator not being the least bit warm?It only does this occasionally. What is the most economic setting to have the boiler on?
There probably is a leak, cuasing the boiler to have to refill with water. The most effective setting is to get the water hot enough so it does not have to keep running.
First, if it's a hot water system, check the psi on the boiler. If you don't have an auto feed, you have to maintain 15 to 20 lb. in the system. You could be low on water psi and may have air in the system. Check the psi and bleed the air out of your radiators. If it's a steam system, you shouldn't have any water in the radiators, Unless you have a leak in the hot water coil inside the boiler. But if that was the case, would be getting water coming out your steam vents. Normal setting for temp. on the boiler is 160 for the low setting and 180 for the limit. This is the best answer I can give you without seeing the system. A lot of other things can come into play, but this is the most common problem.
