Problem is the boiler won’t run more than 15-20 minutes a day.
That's fine it gets the system flowing, the x800 will just sit in the system doing its job. It might even unclog it enough to keep the boiler running in that 15 minutes. It's powerful stuff and only designed to be in the system an hour or so, although can be a bit longer.
Ideally you'd need to install it as close as possible to the boiler so via the filter if possible