dodgy vaillant

[dogbot]

after my vaillant combi has been running for about 2 hours the upstairs radiators go cold , the boiler is still on and working. if i switch off then back on it`s ok for another 2 hours.
there is no model number but i think it`s about 5 or 6 year old.
any ideas guys.
thanks

 

[gas4you]

What about the downstairs radiators?

What is the pressure guage reading when rads are cold. Should be just over 1 Bar.

 

[superdupergasman]

you dont happen to have thermostatic rad valves and they are turned down to 2 or 3??

They will turn themselfs off. when the rooms heat up.

 

[dogbot]

What about the downstairs radiators?

What is the pressure guage reading when rads are cold. Should be just over 1 Bar.

downstairs rads take longer but also go cold.Pressure is 1.1bar.
all TVRs set at number 5.
thanks for the reply

 

[dogbot]

When the rads go cold the boiler still shows 1.5 bar pressure(drops to 1 bar when boiler is off) the temperature gauge drops from 80 to 40, we can still get hot water from the taps, all tvrs are set to 5, (there is no room stat)

any ideas guys
i`m at a loss.

 

[gremlin16]

Room stat maybe

 

[dogbot]

Room stat maybe

 

[dogbot]

There is no room stat fitted[/quote]

come on guys any ideas.

 

[bengasman]

Could be dodgy bypass

 

[mickyg]

When the rads go cold press the "i" button and let us know what S number you get. Its possible you might have a sticking diverter valve, but the problems wouldn't normally be exactly how you describe.

 

[dogbot]

There are only 2 clocks on the boiler, a pressure gauge and a temperature gauge.

 

[bellairaphon]

have u had that problem from the start?? try closing the upstairs rads on the trv try push the water down stairs. see if that helps. then open up gradually. pump could be on way out or maybe system could wat some x400 in then replenish with x100 after a few weeks with x400