Had some Thermostatic Radiator Valves fitted and the CH pipes are now making Chugging noises?

You say that the valves are bi-directional, but have they been set the correct way?? You need to feel which pipe gets hot first on each rad. this is the flow pipe, then make sure if the valve is set for FLOW or RETURN depending which pipe it's on. It certainly sounds as if the pump is pumping against the valve instead of through it. ADDED>> Keith- it does matter with most valves, certainly with Danfoss, they can be fitted on the flow or return but it is essential that the valve is turned 'internally' to match. I dont know what make of valve YOU have but here is the setup for Danfoss. <a href="http://randall.danfoss.com/PCMPDF/013R9355_RAS-c2combi.pdf" rel="nofollow">http://randall.danfoss.com/PCMPDF/013R93...  more