Pressurised System Overflow Drip

Hi If you have a pressurised hot water system (unvented cylinder)? it will have a expansion vessel and you maybe have one independent for the centralHeating aswell it may have developed a leak as you’ve disturbed it! Depressurise the system and tighten any joints if not a new part may be needed Thanks

If you have an pressurised (unvented) hot water system, this is unlikely to be affected by removing and replacing a radiator. I'm guessing you mean a pressurised heating system. First thing to check is the system pressure on the gauge next to the valves you used to re pressurise the system. This should be around 1 Bar when the system is cold, it rises as the water in your system expands during heating but if it reaches 3 bar then the pressure relief valve will open, hence the dripping pipe (this is an essential safety feature and must NEVER be bypassed, capped off etc). If all is ok with pressure when cold and the pipe still drips, I would strongly recommend you engage the services of a qualified plumber.

the red expansion vessel will be for the central heating circuit ,check vessel pressure,check the prv on it,have you over pressured heating check gauge.

Whilst checking for any leaks it's worth checking the air pressure in both expansion vessels. Static pressure should be @ 1.5bar. This should be checked by a qualified heating engineer.

Did you drain the system useing a pressure relief valve. The valve is like a tap. Rubber washer that seats down and stops water passing. Sometimes dirt can stick under the rubber and allow water to pass. Normally you would find the offending relief valve and twist it up till it snaps down again. If you flick it like this a few times it normally reseats itself. Otherwise its a replacement . There easy and inexpensive to fix.