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George-Allsorts
George-Allsorts, Senior Appliance Technicial Manager
Category: Appliance
Satisfied Customers: 1448
Experience:  A whitegoods technician with 30+ years service in Domestic Appliance Service & Repair, and General Mechanical & Electrical Repair
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my vaillant boiler pressure is dropping off to 0 bar. What

Resolved Question:

my vaillant boiler pressure is dropping off to 0 bar. What do i do to boost it up?
Submitted: 2 years ago.
Category: Appliance
Expert:  George-Allsorts replied 2 years ago.
George-Allsorts :

Hello, my name is***** be patient whilst awaiting any responses as I'm not constantly available.

Under the boiler there should be aa filling loop with two taps on it.. can you see it?

Customer:

yes i can.

George-Allsorts :

Can you also see the pressure dial

Customer:

the pressure dial is on 0 now and the boiler is on

George-Allsorts :

Is the boiler actually running then?

Customer:

the boiler didn't fire and i boosted the pressure by turning the valve on the silver pipe of the tank and pressed the button of the boiler and it fired up. Now the pressure has dropped to 0

George-Allsorts :

OK.. it must have been really empty, or, you may have a leak somewhere...

Turn the tap again, but do it a little at a time... until it reaches 1.5 bar... Then bleed the radiators one by one, toping up the boiler as you go.. No higher than 1.5 bar though

George-Allsorts :

When you have finished, turn both taps off

George-Allsorts :

Please take a moment to rate my assistance.. Please use the smiley faces to do this.

George-Allsorts :

Is the boiler rising and staying risen now?

Customer:

the pressure has reached 1.5 bar but it is coming down as before

George-Allsorts :

Have you bled the radiators?

Customer:

yes. you mentioned two taps on the filling loop. i have turned the black one on the silver pipe horizontally. The other one i cannot turn

George-Allsorts :

oK.. so long as one will turn.. it is safer to get both to close

Customer:

the pressure has dropped to below the minimum

George-Allsorts :


Then if you have bled the radiators correctly, you have a leak and need a heating engineer to attend to the system

Customer:

is it safe to keep the heating on?

George-Allsorts :

one moment

George-Allsorts :

Do you know the model of the boiler

Customer:

it just says vaillant. The block of flats is 14 years old

George-Allsorts :

OK.. top up the boiler to 1.5 bar and wait to see if it drops again

Customer:

i topped it up to 2 i am afraid

George-Allsorts :

2 bar is ok... 1.5 bar is the ideal, but 2 bar is still safe

Customer:

but the dial is coming down

George-Allsorts :

how fast?

Customer:

it is just above 1

George-Allsorts :

Is the boiler on an outside wall?

Customer:

yes it is

George-Allsorts :

Can you see a leak anywhere near the boiler?

Customer:

not internally

Customer:

is in the kitchen

George-Allsorts :

Now can you go to the otehr side of the wall to see if the system is venting to the outside

Customer:

it is dark and i could no see anything i am afraid

George-Allsorts :

What is the pressure now?

Customer:

it has dropped to 0 again

George-Allsorts :

You have a very prominent leak then.. this could be anywhere that the pipes run... Turn off the central heating and the boiler and call a heating engineer as soon as possible

Customer:

ok thanks

George-Allsorts :

I hope you get it sorted without too much interruption to your holidays

George-Allsorts :

Please take a moment to rate my assistance.. Please use the smiley faces to do this.

George-Allsorts :

Hello, Just a follow-up to ask how you got on with your boiler issue last evening...

Please feel free to return for further assistance if you need

George-Allsorts and other Appliance Specialists are ready to help you