My top tip and best advice for draining central heating systems is don’t try this at home! You are much better off getting a professional in like me if you’re in the Oxford area. It’s not that it’s a hard job, any competent DIY guy can drain central heating systems. The thing is any mistake can be costly and mistakes are often made. A plumber drains central heating all the time and so is experienced, a builder or DIY guy isn’t, also a professional plumber has insurance! If you still want to do it yourself, OK… here are some tips worth considering before you start.
Before Draining Central Heating Tips
Before draining central heating systems ensure its a vented system the type with an expansion tank in the loft otherwise known as a header tank (with toilet ballcock). Combi boiler type heating systems are much trickier and it is best to call an Oxford plumbing firm.
Make sure the boiler or pump can’t start up by switching everything to the off position and zero the thermostat dial, remember to put back to how they were once you are done.
Prepare tools , 2 trays (that fit under) bucket , hose , rags/towels (and a friend in case of any mistakes).
Remember to take up the loft a broom or something to put across tank and a bit of string to tie the ballcock up.
Inspect the ball if there is water inside replace it – they only cost a few pennies!
Open the upstairs bleed valves slowly to allow the water to run out faster, when the pressure has dropped open the downstairs ones.
When the water has stopped it doesn’t mean the system is empty! There could be an air lock – read on!
When the water has stopped go back up the loft with a bucket a scoop and rags/towels , as you will probably need to clean the gunge out of the bottom of the tank . Taking care not to let any go down into the system!
Now to check there is no air locks untie the stop cock and let a good bit of water run down the pipe, a few seconds you should hear your mate shout up. If so good no airlocks the system is drained tie it back up go down.
If you have an air block you can squirt water back up the way from the tap via the hose, of course remembering to close the bleed valves first!
Refilling After Draining A Central Heating System
Refilling after draining a central heating system is bit of a reverse process but still requires a bit of thought to avoid any problems.
Close the drain cock, close the bleed valves.
Go back up the loft and fill the expansion tank remembering to take the inhibitor with you! Tip it in slowly as the tank fills so it can get in the system not just the tank!
Wait up there until the ballcock has stopped the water to make sure it works properly! Ok finished up there put the lid on.
Go to the downstairs radiators and bleed them one by one and then do the upstairs.
Be sure everything is tightly closed, switching all back to how it was then fire up the boiler.
Turn the thermostat up, to bring the system to heat up it will probably make knocking and creaking noises!
Now you can try to bleed the reds of any air left in them (will be hot this time – yeh!).
Lastly when the system has fully heated up, check for any leaks.
That’s it – job done well done!