It is until you fit the flue diverter that was made for it on and then fit a flue at which point it's not flue less any more.The ops boiler is flueless
Adding a flue to it is absolute madness, modifying abs appliance way beyond its original spec
I stand by my first remark on it
I converted many, can't be arsed to dig out the regs but for a single point hand wash with no flue you were suppose to have a sign saying max 5mins use max, if it was connected to remote it had to have flue.
In the 70s and 80s there were thousands fitted with no flue, caravans and houses had a deflector to stop scorching caravans which at the time were a small box with very poor ventilation and remote taps ignored any advice and sold them like that, in correct operation with correct ventilation it's fine.
As I said before it's all pointless conjecture as it's not happening, you can stand by what you say.
