Low pressure, no leaks found

Turn boiler off at the wall. Raise the pressure back up to roughly 1.2bar slowly as to not introduce air to the system. Flick the gauge with your finger as you are doing so as I have fitted new boilers where the gauge was sticking slightly therefore giving me false pressure readings. Look for any visual signs of water ingress around the boiler and rads. They will most likely be wet when the heating system is cold so have a feel around checking all visible connections. Turn boiler on and check again. Turn heating on and allow rads to get hot. Check the prv to see if it is dripping OUTSIDE. This should be a copper pipe angled towards the wall behind where the boiler is fitted. If it is dripping or is wet it may have a failed. Remember that if the prv has failed usually the expansion vessel is to blame. May require recharge or replacement. Generally speaking the prv would also need replacement as depending on how long this has been going on for it may be weakened there opening prematurely. Pressure testing and thermal imaging would be my next step if all else fails.

If the boiler was only fitted in February and it’s a fault with the boiler it will have a minimum of 5 years warranty up to 10. Give them a call your installer should have registered it with them There shouldn’t be any charge.

I’ve had it we’re the water jacket leaked into the condense so you wouldn’t see the leak

The previous answers are very good, they could of added that you can determine if the leak is on the radiator pipes and system or the boiler itself by turning off the central heating flow/return service valves underneath the boiler and checking if the water pressure still drops. If the water pressure drops then you will need to contact the manufactures to have there own engineers to repair. If the water pressure drops when you open the service valves underneath the boiler then it is somewhere on the system and you will need to get a GasSafe engineer to investigate.