Am I allowed to drain down a Combi Boiler - or do I have to use the services of a "Competent Person" or Corgi Registered Plumber? If I'm allowed to do this - are there any tips or advice you can offer? The reason I'm doing this is to fit two new radiators (different sizes to the existing ones in place). Thanks.
Yes you can drain your' system down if you feel able.
Under the boiler there will be taps on the flow and return pipework normally red knobs. Turn these off,you will then need to find a draincock,attach hose to outside, open draincock.
Attach hose to a drain point and drain system. With pressurised systems the system will only refill when you attach or open the combi fill - so no need to isolate the boiler flow and return, depending on the make of boiler the isolation taps are normally left well alone, as many are prone to leak if disturbed.
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