Bleeding a Vaillant combi boiler

Postby teliow » Wed Nov 19, 2008 4:54 pm

Hello All

I need to cut the water supply pipe to a Vaillant combination boiler and would like to know what I need to do once the pipework is complete.

Do I need to bleed the boiler for example? and if so what's the process?

Opening the hot taps and shutting them down once air has stopped I assume will clear the domestic hot water system but what about the central heating? Does the Vaillant do this itself?

There is no separate / independant isolating valve (other than the one on the boiler mains input) so I will put one in whilst moving the pipework.

I assume that in cutting the supply pipe the water which is in the pipe from the boiler back to the cut will run out therefore leaving air in the pipe when I reconnect - this is my concern.

Any advise (before I give in and call an engineer!) will be gratefully received.


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Simply Build It

Postby plumbbob » Thu Nov 20, 2008 2:34 pm

If you mean cutting off the cold water mains supplying the combi, then you don't have to do anything afterwards other than run the hot tap. This will clear all the air out of the pipe.

The heating is a separate system and will not be effected by cutting the pipe. Vaillant boilers, if they are newish ones, have isolator valves fitted as an integral part so no further valves are required.
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Postby htg engineer » Thu Nov 20, 2008 4:33 pm

Supply pipe ?

It sounds like your talking about the cold water inlet ??? Therefore the Central Heating wont be affected.

Just turn water off, do whatever needs doing - turn water back on - air will clear itself.

htg engineer
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Postby teliow » Fri Nov 21, 2008 2:09 pm

Many thanks
Plumbbob and Htg engineer info gratefully received


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