Unsure how to repressurise boiler

[HannibalSmith100]

My parents have just moved into a new house and they have never had gas central heating before so I was showing them how to use it. I noticed that the water pressure in the system was a bit low so I googled how to repressurise their particular boiler (a Vaillant ecoTEC Pro 24).

This seemed straightforward but the filling loop didn't have a handle valve at one end, it just has two isolation valves (see photos 1 & 2). I just figured it was a bit different from the one in the video guide I was watching but then realised that one of the valves appears to already be in the 'on' position with the screw head of the valve being in line with the pipe. This is where I admitted defeat!

I've included a screen grab of the video guide for reference (see photo 3) and their filling loop also has one of the valves in the 'on' position but I think that's because it then allows you to use the hand valve behind it unimpeded.

I'm not sure if I need to close the open valve first and then follow the guide, or if it was left open for a reason? I'm not even sure which pipe should be opened first if I do follow the guide as they both look the same without a hand valve at one end!

Can anyone advise please?

 

[terryplumb]

Turn the isolation valve on ( slot in line with pipe).when done ,close both to off.

 

[ianmcd]

as @terryplumb says, but use a good sized screwdiver, someone has been using one with too small a head and it is chewing the valve screw, get the heating restored and book someone to replace that cheap crap with a decent filling loop

 

[HannibalSmith100]

Thanks for the feedback. As I was hoping it seems simple enough to repressurise. Is it detrimental that someone has left that valve in the on position though? Could that have contributed to the current low pressure?

As for a decent filling loop, would that be one with a hand valve?

 

[terryplumb]

No,it won't contribute to lost pressure. Having two valves reduces the risk of inadvertantly having the loop open.
Those valves with slots for screwdrivers are not great and tend to weep after a while. The ones with handles are more user friendly and reliable.

 

[HannibalSmith100]

Cheers terryplumb, appreciate your help.