Few questions about Boiler/pressure

[humptyd]

Had some builders in yesterday returning to fix a small leak on a basement radiator (old pipe connected to new pipe at radiator). After changing the old pipe for a new one they tested all the radiators and said they were working (hot).

The layout is :-

basement 2 rads bathroom and shower
ground 3 rads and boiler
1st floor 3 rads
2nd floor 1 rad and small bathroom (sink/shower)

After I returned, I noticed however that the 2nd floor rad was not working and the shower wasn't running correctly (cold with low pressure on hot).
I bled the 2nd floor rad but it was already full of cold water.

Turning all the rads off below the 2nd floor got the flow going again and the shower was working again. Since I've turned the other rads back on the 2nd floor rad is fine but I'm still having problems getting the shower to kick in (low pressure and cold on every setting except heat on max).

Currently all the rads are fully open. Does this matter or should I have different settings coming away from the boiler?

The boiler has a red dial set at 1.5bar with a max. centr. heating pressure of 2.5 bar. Should the black marker be at around 1.5bar with the heating off or on?

Secondly, I have an old Vaillant boiler (was already in house in 1997) and it doesn't kick in when running hot water anymore and therefore hot taps are cold. It used to be a bit intermittent, one day working, one day not, now it just doesn't work and to get hot water we have to put the heating on. Any clues what that prob is? An easy fix?

Any help gratefully received

 

[Paul Barker]

1 to 1.5 cold if it goes much over 2.25 hot pressure vessel may need charging.

Diaphragm, not really diy if you have to ask these questions.

 

[humptyd]

Thanks for that, everything seems to be as it was (including the radiator which was cold) BAR the shower. It's a Triton T80si.

In the same room (top floor) there is a wc (which I've got it into my head is not flushing as powerfully as it was tho' I could be wrong!), a mini basin and shower. In the next room there's the rad that had cold water in and that's it on that floor.

The shower has 3 settings cold, hot 1 and hot 2. It's usually kept on hot 2 setting about no.6.

However once turned on at this setting it shows half green/half red on the pressure setting and hence blows cold. If I knock it up to temp.7 (or higher) it kicks in and I can bring it back down to 6 and it's ok.

Switching it to hot 1 setting or 'cold' the pressure is lost again though (or if I turn it down less than 6 on hot 2 setting it starts to lose it too).

When I used to flush the toilet (with the shower on) the pressure would be lost for maybe 10-15 secs at which point it kicked in happily again but the pressure was always ok whatever setting I chose.

It's just that teensy weensy bit of pressure off what it was and I'm flummoxed. Not much to go on I know