It`s a very simple task but I have no experience with this style of boiler.Central Heating.How to drain %26amp; refill a combi boiler [ Vaillant VCW GB EH ]system to change radiators?.?You do not need to drain and refill. All you need to do is to turn off the radiator valves and disconnect the them. The water will remain in the pipes. The radiator will be full of black water so put down plastic sheets and drain into a bucket. Then when you reconnect, the system should automatically fill. Best of luck. Leave bleed valves open at the bottom rads and when they are full the water will leak out. Then shut the bleed valves. Leave the upstairs ones open and do the same.Central Heating.How to drain %26amp; refill a combi boiler [ Vaillant VCW GB EH ]system to change radiators?.?Ensure ALL of your radiator valves throughout the entire house are turned ON. You should have little 'drain off' valves on the lowest points of the heating pipe work or on the down stairs radiators. If your boiler is at the lowest point of the system then you may find a drain off beneath the boiler as well. Attach a hose pipe to one of these and open it. This will start the draining process, as you hear the system draining, go upstairs and open the bleed nipples on all the upstairs radiators, you'll hear a sucking noise as you do this, if water comes out then wait a few minutes before trying again. Doing this will allow air into the system which will force all the water out of the drain off you've already opened. If you have more than one drain off then, after the first has run dry, tighten it up and repeat the proceedure with all the other drain off valves. This will ensure you've got every last drop of water out of your system.
Once you've done the work you need to do, and with the system still empty, tighten up ALL the drain off's you've opened before taking off the smallest radiator. Shut both the radiator valves and remove the 1/2%26quot; cap from the top of the radiator. Pour your inhibitor into the radiator, replace the cap and reconnect the radiator opening both the valves once you've done so.
Ensure you have tighten all the bleed nipples on the upstairs radiators and go to the boiler. You'll probably see a thin silver braided hose right up underneath the boiler close to the water and gas connections. On each end of this hose there will be a small black tap, turn one tap fully to the open position (they will only turn 90 degrees and maybe quite stiff) then turn the second tap slowly, you'll hear water rushing, this means the system is filling. Keep your eye on the pressure gauge on the front of the boiler, when this reaches 1.5 bar turn both taps off fully. Start bleeding with the lowest radiator, keep going back to the boiler to check the pressure and top up where necessary. Once all the radiators have been bled, top the pressure back up to between 1 and 1.5 bar and you're ready to fire the boiler.
Hope this helps?Central Heating.How to drain %26amp; refill a combi boiler [ Vaillant VCW GB EH ]system to change radiators?.?ANF is quiye correct. You do not have to drain the whole system, just drain the rads you want to change.
