Was always taught to never air test water pipes, as air can be compressed and build up to dangerous levels. the leak detection companies use a gas and a sniffer, best way.
i assume you have checked the new cartridge for whether it is reverse thread? been caught out a few times with that on shower valves. Look at the new cartridge and see which way the threads go - although some makes changed during...
check they are tank fed, then put a bung in the tank outlets and open a couple of taps elsewhere to drain what is in the pipes. i had an electric pipe freezer which made jobs like this easy. and put isolating valves in while you have...
check they are tank fed, then put a bung in the tank outlets and open a couple of taps elsewhere to drain what is in the pipes. i had an electric pipe freezer which made jobs like this easy. and put isolating valves in while you have...