HELP vaillant combi,working,noisy.no c/h no h/w

enrique · 24 May 2005

Need serious help.No hot water or central heating and noisy boiler after emptying system to replace leaking bleed valve in living room.Switched off boiler and mains water before emptying.bled air out of all radiators after filling.switched boiler on.boiler makes a racket when opening hot water.(only hot for a couple of seconds if heating is selected).boiler makes a racket when timer comes on.water in pipe slightly warm,water return pipe cold.no radiators warm.pressure gauge normal water gauge also normal.no water tank in loft,no idea if or where pump is.VAILLANT COMBI VCW-3 T3W.New to diy.detailed help please & thanx

kevplumb · 24 May 2005

check the auto air vent on the pump

ChrisR · 24 May 2005

It looks like a car tyre valve cap and should be left permanently LOOSE.

I'm not sure it's on the pump - can't remember. If it isn't, look higher!

bengasman · 24 May 2005

if the auto vent does not work your system is most likely corroded, which is why you had the problem in the first place. More likely than not you will find the vent needs replacing, the pump is worn out and the secondary heat exchanger full of goo. Basically either poor workmanship from the installer and poor maintenance. Easy guess as this is the case in 4 out of five problems I see with either Worcester or Vaillant boilers. Good machines that keep working if handled by the book. The way to find out is to fire the boiler up in heating mode and check if any of the radiators is colder at the bottom in the middle between the valves than near the valves. If so the only thing that will really solve the problem is a powerflush followed by replacing parts that are beyond salvage.

Agile · 24 May 2005

It does sound as if you have got air into the boiler and the flow switch is not working. You should have isolated the boiler with the valves underneath before you started touching the system.

The auto air vent in the boiler is the solution. Its to the right behind and above the pump. Take off the right hand side of the boiler to get at it.

The AAV has a metal cap and this should be just loose. However it may be corroded up and poking it with a pin inside MAY get it to let air out but may also cause it to remain open and let water out. Ideally it should be replaced but after the air is expelled screwing the cap tight again will probably suffice.

When the air has been expelled the flow switch, small black plastic part at the front, will move its pin and allow the gas valve to turn on.

Tony

enrique · 24 May 2005

bengasman said:
if the auto vent does not work your system is most likely corroded, which is why you had the problem in the first place. More likely than not you will find the vent needs replacing, the pump is worn out and the secondary heat exchanger full of goo. Basically either poor workmanship from the installer and poor maintenance. Easy guess as this is the case in 4 out of five problems I see with either Worcester or Vaillant boilers. Good machines that keep working if handled by the book. The way to find out is to fire the boiler up in heating mode and check if any of the radiators is colder at the bottom in the middle between the valves than near the valves. If so the only thing that will really solve the problem is a powerflush followed by replacing parts that are beyond salvage.

enrique · 24 May 2005

Agile said:
It does sound as if you have got air into the boiler and the flow switch is not working. You should have isolated the boiler with the valves underneath before you started touching the system.

The auto air vent in the boiler is the solution. Its to the right behind and above the pump. Take off the right hand side of the boiler to get at it.

The AAV has a metal cap and this should be just loose. However it may be corroded up and poking it with a pin inside MAY get it to let air out but may also cause it to remain open and let water out. Ideally it should be replaced but after the air is expelled screwing the cap tight again will probably suffice.

When the air has been expelled the flow switch, small black plastic part at the front, will move its pin and allow the gas valve to turn on.

Tony

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HELP vaillant combi,working,noisy.no c/h no h/w

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