Polypipe floor central heating on suspended floors can be installed using a variety of methods. Pipe can be laid along the joists using double heat spreader plates or across joists on battens using single heat spreader plates. Pipe only systems can be used where heat outputs are less critical. Where joist centres are 350mm to 450mm double heat spreader plates can be used to span the joists and support the pipe at 250mm centres (225mm average spacing). These plates run along the joists and are positioned to allow the return bends to cross joists through pre-prepared notches.