Gas boiler water pressure question

cubix

I have a Myson Potterton gas boiler which heats a 3bed semi 7yrs old. Got it serviced the other day and when the lad was doing it he told the other half a couple of them in the estate had seized due to lack of water. In the attic there is a small water tank with a ball cock which is feed from the mains and this is where the heating gets topped up from if it looses any water I presume. As you can see from the picture my water pressure dial is barley off 0 and will drop right back to 0 when its running.He reckoned the dial should between 1-2 on the dial. The little red dial is on the outside of the clock which I can move manually, which I presume is a maker to make sure the black dial does not go beyond
According to him instead of the boilers being feed from the tanks they should have been piped directly to the mains, does this sound right. When I got home checked in the attic to make sure the heating feeder tank is full which it is. So if there is not enough water in the heating system going by the dial what is usually the problem, air lock from the feeder tank into the boiler. Is there anything I can try to get the pressure dial up before calling a plumber back

Thanks

10-10-20

If there is a feeder tank in the attic then this isn't a pressurised system and will remain at what you see there.

cubix

Theres three pipes in the airing cuboard 2 x 25mm which I think is the hot and cold feed for the house and a smaller pipe maybe 15/20mm which he said was the feed from the attic to the boiler. As far as she remembers he said there was a one way valve( in the direction of the boiler i presume) on this pipe, so would this be a type of pressure system.
IF my system is not a pressure system can anyone tell me what the dial is for?. As it would kind of make sense what he was saying regarding the dial giving you an indication if you had enough water in your system. Does anyone know do boilers have a cut off saftey if there isnt enough water in your heating system or is it just a case your pump gets it

Thanks

garyh3

Has the dial ever been higher (with the boiler off) say .5 bar or 1 bar.??

Does the boiler turn on ?

cubix

I am nearly sure when the system was new it use to sit up around the 1bar mark. The boiler is working fine but was hoping to find someone else on here with the same boiler/system who might be able to tell me if what the plumber said is correct and not just chaning his arm

Cubix

flocker

Some boilers can be fed either from the mains or from a header tank. If the boiler is running and has been for the past number of years leave it alone. You have got it serviced.
Most have devices to check if their is enough water/pressure in the system and wont operate if its low.