anybody advise me on this?when in use it constantly vents to outside.at a steady dribble.could it be the pressure valve on left not seating,the one with the 3 bar lable on it. also I have no manual with this and would like to know how to regulate the system pressure to 1.5 bar,is it the same valve?regards phil.
"when in use it constantly vents to outside.at a steady dribble.could it be the pressure valve on left not seating,the one with the 3 bar lable on it."
PRV faulty or system pressure too high.
"also I have no manual with this"
"and would like to know how to regulate the system pressure to 1.5 bar"
If your system is losing pressure you have a leak somewhere which should be found and corrected.
If your system is gaining pressure then the filling mechanism is adding water. Do you have a plug-in filling link or a filling loop? If you have the built in link make sure the valve is shut and the key is out. If you have a filling loop ensure that the service valve is shut and the loop disconnected. That will stop any pressure increase.
To increase pressure to 1.5 - 2bar use the filling mechanism and ensure its all disconnected afterwards as above.
To reduce pressure let water out of the system via your drain c o c k.
I'm not totaly sure what or where the loop is,as I remember these closed systems with hot water on demand have as you say a loop of pipes with ball tap's to "charge" the s/h system but this has not a sign of any loop. I take on board what you are saying about the pressure valve not sealing but can it be removed,stripped and repaired or do I have to purchase a new one and bin the old one? regards phil.
What is the reading on your pressure guage? If its too high and the filling system isn't isolated then the PRV will operate and you'll get your leak!
If its dropping then the PRV isn't seating properly and the filler mechanism will be shut off.
If its in the correct area constantly then you could be looking at a situation where the PRV is letting by but the fill mechnism is topping it up at the same rate.
So theres lots to check before getting involved in changing/fixing a PRV that may not need to be fixed!
"When in use" from the original post implies that it only drips when the boiler is fired up. That says to me a further possibility. The pressure is too high in the system when it is cold (2+ bar) so when the water is heated the pressure will rise to above 3 bar and the PRV (set to 3 bar) will open.
Let some water out so that the pressure is 1 - 1½ bar when cold and see what happens when the system fires up.
As you say you can't find a filling loop then I suggest you have the built in link. Its accessible by droppingthe front panel and pulling out the "tray" that sits under the boiler (if said tray is actually there!!) Make sure the valve is shut and the key removed.