Well, I'd be very careful as if the shelf has been bending so has the
plumbing connecting it to the system.
Can you empty the system, that would make it lighter. Then leave the
chipboard shelf and build supports underneath it to carry the weight.
What clot used cheap chipboard in the first place?
However do be sure there is no risk of the heater coming on during the
work, and also watch for airlocks when turning the water back on.
A useful gadget for helping here is a length of strong hose that can be
clamped to taps to pump mains water back up the system to remove those
annoying hammerings due to trapped air.
Also, if the tank is making a lot of noise, maybe you need to look at the
heater and replace it now.
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