filling loop confusion

hostudle

I noticed the past week or so that my heating seems to be struggling. Checking the boiler the water pressure was at 0.7 which seemed low especially while it's hot and working. My first thought was that I should use the filling loop to increase that up to at least 1 bar.

The filling loop is in the hot press upstairs connected to the water tank in the attic and seems to be covered by a couple of valves. I tried to post some pictures but I can't: The first one is a red handled valve that I turned anti-clockwise. The second is a simple screw above the silver-braided hose which I turned so the notch was vertical in-line with the pipe. The last is a black handle which again I turned to be in-line with the pipe.

I opened them all up but I didn't get any sound of water flowing. I did it only for a short time since I have to go downstairs to check the pressure, but there's definitely nothing happening.

The boiler is a Vokera Mynute 20e and everything I can see online says that to repressurise you just have to open the filling loop for a short time, but I don't know if that assumes a mains connection at higher pressure.

So I have two questions. Am I missing something obvious that I should be doing - should using the filling loop be as simple as opening those valves? And also while I'm no plumbing expert, how should this be working when the attic tank will give maybe 0.5 bar pressure at best?

John.G

The low pressure switch is set at 0.5 bar and you probably have this system (extract from users manual).

LOW PRESSURE
SEALED SYSTEM
An alternative method of
filling the system would be
from an independent
make-up vessel or tank
mounted in a position at
least 1 metre above the
highest point in the system
and at least 5 metres above
the boiler (see fig. 5A).
The cold feed from the
make-up vessel or tank
must be fitted with an
approved non-return valve
and stopcock for isolation
purposes. The feed pipe
should be connected to the
return pipe as close to the
boiler as possible

hostudle

Thanks, I saw that in the manual but I didn't really understand what it was implying. Does that mean that the filling loop I found isn't intended to work normally, and I can't re-pressurise the system unless it's completely empty/drained? The pressure was up at 1 bar before the winter so I thought that it having dropped would affect the performance of the heating system. Will any pressure above 0.5 work just as well, or is 0.5 the minimum for it to work?

John.G

0.5 bar cold static head is quite adequate for circulation in a 2 storey house and a tank in the attic will give slightly more than this as its above the u/stairs rads & hot water cylinder, I don't know how it was at 1.0 bar cold during the summer as you can't get any higher than the head pressure supplied from this tank which I would expect to be 0.5 to 0.6 bar, 5M to 6M head.