My 4 rads downstairs TRV's all make an annoying hissing sound after an hour or so, i know the valves are OK because i have swapped them round with the upstairs ones ps if i adjust the temp on them this seems to make the noise go away (for a while anyway then i change the temp again)

Not sure what you mean "Mark M." <markm@techz.net> wrote in message news:4717f5b0$0$28874$4c368faf@roadrunner.com... > Barry wrote: >> My 4 rads downstairs TRV's all make an annoying hissing sound after an >> hour or so, i know the valves are OK because i have swapped them round >> with the upstairs ones >> >> ps >> >> if i adjust the temp on them this seems to make the noise go away (for a >> while anyway then i change the temp again) > > Are you sure water flow is the direction of the arrow on the TRV? > > Mark M.