pressure loss on a morco feb24e boiler

[Andy231075]

Please can anyone help, we have a static caravan with a morco feb24e boiler over the past few months the boiler keeps losing its pressure ive checked for any leaks in and under the caravan but didn't find any i did notice the prv was weeping slightly so i got it replaced i also had the expansion tank replaced aswell also i had the automatic air valve at the back of the pump replaced too but the plumber that replaced the prv said that the aav doesn't look like a new one now could that be the problem as i don't know what to do next. Also should the little black screw cap on the aav be undone or screwed down?

 

[lame plumber]

need to get hold of a decent technician who actually resolves your problem not just swapping parts through. it may be just a weeping rad valve causing the pressure drop in the first place if the prv was ok initially