db1979 wrote:Welcome rvn.
Pumps don't need to be super powerful so water feature/pond pumps can be used if setup correctly. These use a lot less power than a water transfer pump and I suspect that if you're running in a bathroom you'll have limited access to power. You don't want to overload your GPO. Coffe addict uses a solar water heater pump off ebay that sounds like a good cheap option that runs on lower power and also handles high temperature (not that you want high temperature in cooling water) so it can also be used to drain the boiler.
Many thanks for the welcome and info db1979 - was able to hunt down the threads and have purchased the same pump as Coffe addict: https://www.ebay.com.au/itm/112453512610
Cheers