Today I came to Grants Auburn Bay rental apartment because the tenant has explained that the radiators are too loud. Upon inspection I found the single zone radiant heating system is working well and the sound heard is standard with a system of this design. You can hear water flow and turbulence of water which is normal. We tested the system on and off and the sound goes away when the system is off as is should as there is no more water flow. The system is running properly and there is nothing g else that can be done. A new zone valve may quite the system but is not guaranteed. A 4-5 year old valve should still be n good working condition.